Note: Descriptions are shown in the official language in which they were submitted.
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MULTI-PHASE ENERGY ABSORBING AND IMPACT ATTENUATING MODULES
BACKGROUND OF THE INVENTION
Field of the Invention
This invention pertains generally to mufti-layer energy absorbing and impact
attenuating articles,
particularly honeycomb and foam articles with or without facing sheets
integrated to the core, that
form mufti-layer modules designed to enhance absorption of impact energy and
attenuate in a
controlled fashion an impacting body by plastically, elastically or
viscoelastically deforming,
crushing or compressing upon impact thereby reducing potential. injury and
damage resulting from
an impact.
More specifically, this invention relates to mufti-layered honeycomb, foam, or
articles of other
energy absorbing materials of similar or varying sizes fused or bonded
together by common facing
sheets or surfaces, or otherwise fixed or positioned adjacent or in
juxtaposition to one another to
form an integral energy absorbing and impact attenuating module in which the
individual layers are
generally designed and manufactured to provide a specified crush sequence
within and/or between
layers in the module, mufti-phase energy absorbing response and controlled
attenuation of an
impacting body of low to extreme impact energy. It will be understood that the
term honeycomb
core also includes modified honeycomb and honeycomb-like structures and that
the term foam
includes any energy absorbing foam material or reinforced foam. material that
has compressive or
crush strength including expanded polystyrene, expanded polypropylene,
polyurethane, vinyl nitrile,
viscoelastic, open-celled, closed cell and metallic foams.
The energy absorbing honeycomb, foam, and articles of other energy absorbing
material may be
designed to be effective for a single impact only, i.e., plastic deformation,
or for multiple impacts,
i.e., elastic or viscoelastic deformation, by varying the material ~ztilized.
The cores, panels or articles
are positioned relative to one another in the specified configuration of the
present invention
described herein to load, reflect and transfer an increased or ma~:imized
amount of impact energy
between and/or within layers or segments of layers in the integral module as
it is compressed,
crushed or deformed to enhance its energy absorbing characteristics relative
to single layer or single
density energy absorbing structures. The energy absorbing modules are
positioned to intercede in an
impact between an impacting body of variable mass and energy with a receiving
body, e.g., a
racecar colliding with a receiving body such as a concrete barrier, or a head
with an energy
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absorbing liner in a sports or crash helmet, so used to not only absorb the
impact energy but also
attenuate the impact energy in a controlled and designated fashion, thus
producing a specified
deceleration response which cushions the impact and minimizes abrupt changes
in impact
dynamics.
The mufti-phase energy absorbing and impact attenuating modules of the present
invention
described herein have broad and varied applicability in manufactured articles,
for example, in the
automotive, motor sports, sports and recreation fields. Several aspects of the
present invention are
provided to demonstrate the inventiveness, r~velty and utility of the claimed
invention. The aspects
of the invention described are a mufti-phase energy absorbing and impact
attenuating barrier system
for use with racecars and automobiles; a mufti-phase energy absorbing and
impact attenuating
bumper assembly and system for vehicles; a mufti-phase energy absorbing and
impact attenuating
structure within a vehicle door, chassis structure, or protective sl:ructure
for an interior compartment
for example, the cockpit surround of an open wheel racecar; and a mufti-phase
energy absorbing
and impact attenuating component of safety or protective equipment, for
example, crash and sports
helmets or other protective equipment and clothing. While specified in the
context of the aspects
and embodiments described herein, the mufti-phase energy absorbing and impact
attenuating
modules may be advantageously used in any energy absorbingarticles in which
the physical damage
of and injury to the impacting body, and its occupants if applicable, be F-
educed or minimized,
regardless of the relative impact energy.
DESCRIPTION OF PRIOR ART
The structural and energy absorbing properties of honeycomb, foam and other
energy absorbing
structures and articles are well known and have been previously described by
those skilled in the
art. Energy absorbing articles of prior art typically utilize a single
honeycomb or foam layer and are
limited by the energy absorbing response characteristic of the single layer.
More efficient energy
absorbing responses in these single layer or single density energy absorbing
articles are typically
achieved by increasing the thickness or altering the density of the article.
In some instances where
physical dimensions are constrained, increasing the thickness of the energy
absorbing material is
not a viable option. Additionally, single density energy absorbing materials
represent a compromise
to overall energy absorbing capacity being either too soft (i.e., low
compressive or crush strength)
when kinetic energies are high, or too hard (i.e., high compressive or crush
strength) when kinetic
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energies are low. In either of the latter situations an abrupt change in
impact dynamics and spike in
deceleration forces which may cause injury and damage occurs when the material
perfectly crushes
if it is too soft, or before it begins crushing if it is too hard.
Because the kinetic energy of an object in motion is equal to l/2mvz, where m
equals the mass of
the object and v equals the speed of the object, the energy which is converted
to force at and during
impact is related to the square of the speed. Thus, as the speed of the object
is reduced by half, the
energy is reduced by one quarter. Additionally, the distance over which impact
energy is absorbed
determines the magnitude of the force and deceleration involved; because
distance is generally
limited in most applications, an energy absorbing article must be as efficient
as possible. The time
over which the impact energy is absorbed is also a critical factor, generally,
the longer the time the
lower the forces.
However, single layer energy absorbing articles have only a single response
characteristic of the
energy absorbing material. For honeycomb, this response generally involves an
initial compressive
strength followed by a relatively constant crush strength until perfect
crushing is approached at
which point the honeycomb essentially becomes a solid and the load increases
radically with little
or no change in deflection. For resilient foam the response is often
represented by a stress versus
percent strain function exhibiting a curve that steadily increases in slope
dependent on the modulus
of the foam until all cells have collapsed at which point the foam essentially
becomes a solid and
the stress on the foam increases radically with little or no change; in
percent deflection or strain.
Honeycomb.
Generally, honeycomb is used in structural applications where strength and
bending stiffness are
required, but with a minimum of weight. One such example is the aerospace
industry where
honeycomb panels made of aluminum or other materials are used extensively in
the manufacture of
aircraft. However, honeycomb is not only useful in structural applications
where strength and
weight are a concern, but also in impac~absorbing applications where strength
and weight are a
concern. Honeycomb has excellent impact-absorbing properties in its thickness
direction because
energy from an impact is dispersed throughout the honeycomb matrix. Since the
cells of a
honeycomb matrix are interconnected, energy from an incident, colliding body
is not only absorbed
by the cell or cells involved, but also those adjacent to the involved cells
by nature of common cell
walls.
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Honeycomb structures and properties are described in terms of their thickness
(T) direction, length
direction (L), and width direction (W). The core is the central member of the
honeycomb structure.
Honeycomb can be manufactured through a variety of processes such as
extrusion, injection
molding, pressure molding, expansion and corrugation that results in a
honeycomb core. The
resultant cells of the honeycomb core may be round, rectangular or polygonal
in honeycomb-like
structures but are commonly produced to be hexagonal in true honeycomb
structures.
Modified honeycomb structures comprise honeycomb cells but may be modified in
their structure,
e.g., containing openings in the cell walls or junctions to modify the
compressive properties of the
honeycomb core. Honeycomb consisting of hexagonal cells may comprise true
hexagonal cells,
under-expanded hexagonal cells where the cell diameter in the L direction is
greater than the cell
diameter in the W direction (L>W), and over-expanded cells where the cell
diameter in the W
direction is greater than the cell diameter in the L direction (W>L).
Typically, honeycomb cannot be
bent to form contours, though under-expanded and over-expanded honeycomb are
capable of
moderate contours.
It will be understood that a honeycomb panel is comprised of a honeycomb core
and a facing sheet
or sheets. A facing sheet is a flat sheet of material fused or bonded to the
open ends in the T
direction of the honeycomb or foam core. Honeycomb cores are capable of
carrying transverse
loads when produced with facing sheets bonded or fused to both. sides of the
honeycomb core in the
T direction to produce a honeycomb panel that also carries tensile and
compressive loads. The bare
compressive strength of a honeycomb core is its ultimate compressive strength
as measured in
pounds (kilograms) per square inch (square centimeter) when loaded in the T
direction. The
stabilized compressive strength is the ultimate compressive strength of the
honeycomb core when
stabilized by a facing sheet bonded or fused to the honeycomb core, i.e., a
honeycomb panel, when
loaded in the T direction. The stabilized compressive strength is greater than
the bare compressive
strength for identical honeycomb cores.
It is primarily the compressive strength in the T direction of the honeycomb
structure that is utilized
for absorbing the energy of an impact. Once the ultimate compressive strength
of the honeycomb
has been exceeded, it will typically deform plastically or elastically, and
crush uniformly, typically
at a constant stress level depending on the core material and its density as
measured in pounds
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(kilograms) per cubic foot (cubic metre). This constant stress level is
defined as the crush strength
expressed in pounds (kilograms) per square inch (square centimeter) and is
described as the average
crush load per unit cross-sectional area. The energy absorption capacity of
honeycomb cores and
panels in the T direction are therefore predictable in load versus deflection
measurements and can
be engineered for specific energy absorption applications. Advantageously, the
embodiments of the
present invention utilize multiple layers of honeycomb cores, articles or
structures with different
energy absorbing characteristics to provide for a mufti-phase energy absorbing
and impact
attenuating response.
As stated previously, honeycomb will initially resist crushing until the bare
or stabilized
compressive strength is realized, and subsequently crush predictably at a
crush energy that is less
than the bare or stabilized compressive strength. Honeycomb cores can be
caused to crush below
the compressive strength through a process called pre-crushing or pre-
stressing. It will be
understood that the terms pre-crushing and pre-stressing are considered
synonymous. Pre-crushing
allows the honeycomb core to crush at its crush strength upon impact without
having to attain the
stabilized or bare compressive strength. Advantageously, the embodiments
described herein may
utilize both pre-crushed and non pre-crushed honeycomb cores, panels, or
articles to provide for a
mufti-phase energy absorbing and impact attenuating response.
Honeycomb panels also have shear strength in both the L and W direction that
is typically
dependent on facing sheet material and facing sheet thickness. Shear strength
in the L direction is
typically greater than that of the W direction for honeycomb panels. Shear
strength is also an
important characteristic of energy absorbing and impact attenuating articles
as incident collisions
may not be orthogonal to the surface of the module, but rather from a variety
of incident angles.
Thus, the energy absorbing and impact attenuating module must be capable of
being resilient, i.e.,
having sufficient shear strength, along its L or W direction so as to prevent
damage to the energy
absorbing capability of the honeycomb panels due to piercing impacts from a
incident body.
Advantageously, the embodiments described herein utilize a sufficiently
resilient facing sheet, outer
shell or protective layer to protect the integrity of mufti-phase energy
absorbing and impact
attenuating modules.
As stated previously, honeycomb cores, panels, or articles have excellent
impact-absorbing
properties along their T direction because energy from an impact is absorbed
and dispersed
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throughout cells of the honeycomb. This dispersion of impact energy generally
occurs within an
individual honeycomb layer (infra-layer transfer) in prior art. However, a
transfer of impact energy
from layer to layer of a mufti-layer integral module (inter-layer transfer) is
important not only for
enhancing impact energy absorption but also to prolong the time over which the
impact energy is
dissipated and attenuate the impact energy in a designated and controlled
fashion. The specified
configuration of honeycomb energy absorbing layers of the present invention
can be utilized to
increase the transfer of energy within the energy absorbing modlule by
producing a specified load
versus deflection response and crush sequence of layers within the module as
it crushes. This
specified configuration of layers also attenuates the impact energy in a
designated and controlled
fashion.
Energy absorbing articles utilizing a single honeycomb energy absorbing
material layer of
consistent configuration, density and structure are not only limited to infra-
layer transfer of impact
energy, but also provide only a single-phase response to impact energy. That
is, the crush strength
for the honeycomb energy absorbing material, panel or article, while both
predictable and capable
of being engineered to certain specifications, is of a single order. Once the
energy absorbing
material has fully (perfectly) crushed, compressed or collapsed in the T
direction under the
compressive load of the impact, the energy absorbing properties of the article
have been exhausted
and the honeycomb core, panel or article effectively becomes solid causing a
significant and abrupt
change in impact dynamics. These significant and abrupt changes in impact
dynamics can cause
'spikes', i.e., very rapid increases, in deceleration forces that may cause
injury or damage.
Advantageously, the mufti-phase energy absorbing and impact attenuating module
of the present
invention utilizes a plurality of honeycomb, foam or other energy absorbing
layers to produce a
mufti-phase energy absorbing and impact attenuating response to an impacting
body that utilize a
compound function of several energy absorbing responses forming an
exponential, logarithmic or
linear response of the appropriate order to reduce the abrupt changes in
impact dynamics.
Honeycomb structures of prior art have been commonly made of materials and
adhesives that are
classified as rigid and deform plastically, such as aluminum, fiberglass,
carbon, NomexTM or even
cardboard. Honeycomb structures manufactured from norrelastic materials are
incapable of
recovering once impacted and crushed. To enhance the energy absorbing capacity
of honeycomb
manufactured from rigid materials, multiple layers of honeycomb panels fused
or bonded by
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common facing sheets have been utilized, each comprising different energy
absorbing properties,
e.g., from highest to lowest crush strength or vice versa. These examples of
prior art, however, do
not produce an enhanced transfer of impact energy nor do they specify a non
successive crush or
compression sequence or claim an optimum relationship between crush strengths
of different
panels. Alternatively, single layer modified honeycomb structures have been
utilized to enhance
energy absorbing capacity. Single layer modified honeycomb structures, while
capable of
modifying the energy absorbing response, are constrained by the thickness T of
the single
honeycomb structure.
Those who have described mufti-layer honeycomb impact absorbing systems
manufactured from
plastic materials include Niemeski (1999, US Patent 6,004,066), who described
an impactor for a
moveable, deformable barrier simulating the front end of an automobile for the
purpose of crash
safety evaluation comprising a plurality of energy absorbing impact segments
each comprising a
plurality of layers of aluminum honeycomb having different crush strength
characterized by
increasing crush strength of successive layers from the outer impact face.
Eskandrian et al. (1997)
also described a mufti-compartment honeycomb material for usf; in a surrogate
reusable test vehicle
used by the United States Federal Highway Administration in crash tests named
Bogie. The multi-
layer honeycomb impactors described by Niemeski and Eskandrian et al. are
designed to simulate a
specific vehicle type in crash tests rather than provide optimum energy
absorbing properties.
Those who have described single layer modified honeycomb structures include
Bitzer (2001, US
Patent 6,245,408) who described a modified honeycomb structure in which the
crush properties are
modified and controlled by crush control surfaces that form openings through
the cell walls at
intersections to provide a reduction in crush strength of the honeycomb cell.
Bitzer claims a wide
variety of crush properties for a given honeycomb achieved by varying the
size, shape, number and
location of the crush control surfaces within the honeycomb in preferred
embodiments of
aluminum, aluminum alloy or cellulose-based materials.
Due to the relatively inelastic materials utilized in mufti-layer or modified
honeycomb structures of
prior art, the impact absorbing capabilities of inventions such as those of
Niermeski and Bitzer
utilizing multiple layers of honeycomb or a modified honeycomb structure are
designed to be
exhausted after a single, severe impact. Additionally, although multiple
layers of honeycomb as
described in prior art will provide for a mufti-phase energy absorbing
characteristic, no specification
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g
has been provided or claimed in prior art with respect to no~successive crush
sequences or how to
advantageously integrate the energy absorbing properties of individual layers
or increase transfer of
energy from the impact throughout the multiple layers of the honeycomb
structure to enhance the
energy absorption and impact attenuating properties of honeycomb.
Prior art also describes the use of elastomeric materials in energy absorbing
applications of
honeycomb. Utilizing materials of elastomeric composition in honeycomb may
provide resilience
for multiple impacts. Utilizing materials of elastomeric composition may also
increase the load
bearing capability and enhance the article's ability to absorb high or extreme
energy impacts.
Utilizing an elastomeric composition that has a moderated or controlled memory
for its original
morphology and controlled rebound characteristics to resume that shape may
both increase the load
bearing capability of the article and its ability to absorb and attenuate
multiple impacts.
Thermoplastic elastomers (TPE) have been selected in energy absorbing
applications due to their
exceptional compressive, tensile and tear strength, resistance to puncture,
and flexibility at low and
high temperatures. Landi et al. (1991, US Patent 5,039,567) have utilized such
a material in a
honeycomb core for impact absorbing bumpers on an amusement ride.
Honeycomb cores, panels and articles may not have the same physical properties
in their T, L, and
W directions, that is, they are generally anisotropic. Honeycomb consisting of
over-expanded cells
produced from thermoplastic elastomers and a fusion-bonding process may result
in a flexible
honeycomb that is anisotropic. Anisotropic honeycomb may be designed with
different attributes in
its L, W, and T directions allowing it to absorb energy and impacts from
different angles. The
impact absorbing properties of anisotropic honeycomb is affected by the
physical properties of the
honeycomb core, the facing material, cell diameter, thickness of cell wall and
the thickness T of the
core. Anisotropic honeycomb may also be used to produce contoured panels
rather than linear
panels and thus are useful in applications where slight contours are required,
for example,
automobile bumpers. Thus, anisotropic, elastic honeycomb can be engineered to
absorb specific
loads, to a desired flexibility, to a specific puncture resistance and to a
controlled rebound.
Advantageously, utilizing multiple layers of anisotropic, elastic honeycomb in
the energy absorbing
and impact attenuating honeycomb modules of this invention provides for
multiple impact, multi-
phase energy absorption and impact attenuation of an incident body in a
variety of configurations
that are compact and of more effective energy absorbing capacity than prior
art.
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It is an object of the present invention to achieve a compound, mufti-phase
load versus displacement
response for mufti-layer honeycomb articles of total thickness T such that the
mufti-Iayer article is
more efficient in its energy absorbing capacity than a single layer honeycomb
of equal thickness T.
Moreover, the time over which the impact energy is absorbed in a mufti-layer
foam article can be
potentially increased by the preferential positioning of successive layers or
segments of layers in the
crush sequence positioned maximally distal from one another by increasing the
distance in which
the stress wave is propagated and reflected within the module.
Foam.
Foam is also well known in energy absorbing applications. Foarn articles
consist generally of a vast
network of minute three-dimensional cells resembling a honeycomb structure
shaped in a
pentagonal dodecahedron configuration (twelve five-sided planf;s). Foams may
be open celled or
closed-cell. Foams may be manufactured from a variety of procf;sses and result
in foams that may
be either flexible or rigid and are generally isotropic in their energy
absorbing capacity. Flexible
foams are primarily used in cushioning or shock absorbing applications while
rigid polyurethane
foams are primarily used as thermal insulators or other similar insulating
applications. Expanded
polypropylene (EPP), flexible polyurethane (FPF) or expanded polystyrene (EPS)
foams are used in
impact absorbing functions. Single density expanded polypropylene (El'P),
expanded polystyrene
(EPS), polyurethane, vinyl nitrite (VN) and other compressible foams are used
in sports and crash
helmet liners of prior art.
Flexible foam is somewhat similar in structure to honeycomb in that the cells
of the foam are made
up of two structural parts, cell walls (struts) and open window areas (voids).
The strut and void
structure allows air to pass through the foam; when a force is applied the
struts and air within the
voids are compressed. The elasticity of the struts acts as a shock absorber
and allows the foam to
recover its shape after compression allowing for use in multiple impact
situations. Expanded
polypropylene (EPP) foam is capable of absorbing multiple impacts, as are
viscoelastic foams such
as open-celled polyurethane foams. Other foam energy absorbing materials may
be effective only
for single impacts. Expanded polystyrene (EPP) absorbs energy by developing
micro-fractures
throughout its structure and thus is effective only for single impact
situations.
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It will be understood that a foam energy absorbing layer or article is self
defining and a foam panel
is comprised of a foam core with a facing sheet or sheets attached to its
surface. Foam is typically
isotropic in its energy absorbing characteristics thereby absorbing energy in
its thickness (T), length
(L), or width (W) directions. Foam may be fibre-reinforced or otherwise
modified to provide for
increased compressive strength in its T direction. A facing sheet is a flat
sheet of material fused or
bonded to the open ends in the T, L or W direction of the foam core.
While honeycomb crushes at a relatively constant crush strength, generally
most resilient foams
exhibit a compression force deflection consistent with Hooke's Law, i.e., the
further the foam is
compressed, the harder the foam pushes back against the compressive force.
Thus, a load (stress)
versus displacement (percent strain) function exhibits a curve that steadily
increases in slope
dependent on the modulus of the foam until all cells have collapsed and the
foam essentially
becomes a solid and the stiffness of the foam increases radically.
The compressive strength of foam energy absorbing materials is typically
measured at 25 percent,
50 percent and 75percent compression (strain, deflection) of the foam
material. Foam materials may
have a complex compressive strength (load, stress) versus strain function of
varying orders that may
be in basic terms referred to as approximating an exponentially shaped
function of various orders.
Some foams, e.g., CONFOR TM made by E-A-R Specialty Composites, may have a
strain ratc-
sensitive stiffness characteristic in which the dynamic properties have a
significantly greater
stiffness at higher strain rates. Energy absorbing articles or structures of a
single (or only slightly
variable) density of prior art have a compressive strength versus strain
function characteristic of the
material, while a mufti-layer energy absorbing article may have several
compressive strength versus
strain functions that may be integrated to form a more efficient compound
compressive strength
versus strain function. This compound function can be designed to cause a
secondary inter-layer
transfer of impact energy caused when the compressive strength of a layer at a
certain strain is less
than the compressive strength of a norrsuccessive layer in the preferential
crush sequence.
The inventive concept of the present invention for multiple layers of energy
absorbing and impact
attenuating articles manufactured of honeycomb cores and panels also applies
to foam. However,
the stress versus strain function of foam in basic terms is an approximation
of a power or
exponentially-shaped function rather than a threshold compressive strength
followed by relatively
constant crush strength as is the case with honeycomb. A compound, mufti-phase
stress versus
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l
percent strain response may be achieved for mufti-layer foam articles of total
thickness T such that
the mufti-layer article is more efficient in its energy absorbing capacity
than a single layer foam of
equal thickness T.
Moreover, the time over which the impact energy is absorbed in a mufti-layer
foam article can be
potentially increased by the preferential positioning of successive layers or
segments of layers in the
crush sequence positioned maximally distal from one another bar increasing the
distance in which
the stress wave is propagated and reflected within the module. A secondary
intra- and inter-layer
propagation and transfer of impact energy within the mufti-phase energy
absorbing and impact
attenuating module can be achieved by ordering the relative connpressive
strengths at 25 percent, 50
percent and 75 percent strain of the different foam layers such that segments
of individual layers
and segments of layers are also positioned maximally distal from their
predecessor in the crush
sequence.
Advantageously, the aspects and embodiments described herein utilize multiple
layers of foam
articles or structures of differing physical properties, e.g., thickn.ess,
density, compressive and crush
strength, to provide for a mufti-phase energy absorbing and impact attenuating
response.
Mufti-layer Energy Absorbing Articles.
Literature on the compound energy absorbing properties of mufti-compartment or
mufti-layer
energy absorbing articles is not common. The inventive concept., embodiments
and aspects of the
present invention are based on a preferential non-progressive crush sequence
of energy absorbing
layers in response to the propagation of the stress wave resulting from the
impact and transfer and
reflection of impact energy between and through interceding layers and
segments of layers of
greater compressive strength in a mufti-layer energy absorbing and impact
attenuating module so as
to partially load or compress the interceding layers.
Yasui (2000) indicates that in the case of a three-layer uniformed build-up
honeycomb panel
subjected to dropped-hammer impact and placed on a backing material of
significantly greater
compressive strength (for example, concrete), the crushing of thc~ panels
occurred in the order of top
panel, the bottom panel and middle panel in that order on drop-hammer testing.
After perfect
crushing of the top panel, the crushing of the bottom panel occurred from the
center portion. After
perfect crushing of both the top and bottom panel, the crushing o~f the middle
panel occurred from
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12
the lower portion of the panel. Additionally, the number of crushing response
steps in the load
versus displacement data corresponded to the number of honey<;omb layers.
Thus, when mufti-layer
energy absorbing honeycomb materials which are backed and supported by a
backing material of
significantly greater compressive strength are subjected to an innpact, impact
energy and forces are
transferred through the energy absorbing material and layers such that
compression or crushing of
the energy absorbing materials against the backing material also occurs. In
the applications of the
present invention, such a backing surface may be a concrete barrier to which
an energy absorbing
and impact attenuating module is positioned against in the aspect of a motor
sports safety barrier, or
the hard, outer liner of a sports or recreational helmet to which the energy
absorbing and impact
attenuating helmet liner is positioned against.
Yasui found that the energy absorption of the pyramid build-up type (prismatic
streamlined) of
mufti-layer panels was superior in efficiency and capacity in comparison to
the uniform build-up
type. Yasui also indicated that mufti-layer panels of the pyramid built-up
type accompanied with the
uniform build-up type can be expected to provide high performance impact
energy absorption.
Pyramid build-up of mufti-layer energy absorbing articles in which the layers
of lesser surface area
are firstly subjected to the impacting object have demonstrated efficiency in
shock absorption
applications because the energy and force of impact is distributed over a
smaller area causing the
initial layer or layers to compress quickly, and then the crushing or
compression of the subsequent
layers of greater surface area occurs more slowly as the layers with the
greater surface area are
loaded. Yasui's results indicate that the crush sequence of layers of similar
or varying sizes in a
mufti-layer honeycomb module are not necessarily progressive from one layer to
its adjacent layer,
and thus the propagation of a stress wave resulting from impact energy can
indeed load layers, be
reflected or transferred between layers or segments of layers in a mufti-layer
module.
It is an object of the present invention to create a designated non-
progressive crush sequence of
layers or segments of layers positioned preferentially maximally distal from
their predecessor in the
crush sequence within the module to maximize the distance the :dress wave is
propagated during
absorption of impact e~rgy, loading (stressing) of layers of greater
compressive strength positioned
between successive layers of the crush sequence, and transfer and/or
reflection of impact energy
between layers or segments of layers of a mufti-layer energy absorbing module
to enhance its
energy absorbing performance. If impact energy is considered to propagate as a
stress wave in an
impact attenuating material, then by increasing the distance over which the
stress wave is
CA 02422415 2003-03-07
17J
propagated through and reflected at layer boundaries as impact energy is
absorbed can potentially
increase the time over which the impact energy is absorbed, which enhances the
energy absorbing
characteristic of the energy absorbing article. if interceding layers of
energy absorbing material of
sufficiently greater compressive and/or strength are positioned t:o propagate
stress waves through to
a maximally distal layer, then some impact energy may be absorbed into heat or
loading of the
interceding layer also enhancing the energy absorbing characteristic of the
energy absorbing article.
Advantageously, the mufti-phase energy absorbing and impact attenuating module
of this invention
provides for an increased transfer of impact energy within the module by
utilizing a plurality of
honeycomb or foam layers of varying physical properties such as thickness,
density, compressive
and crush strengths, e.g., five discrete honeycomb panels or foam layers, in a
preferred
configuration that produces a specified preferential crush sequence of
maximally distal layers
within the module and loading of layers that intercede between successive
distal layers of the crush
sequence with impact energy that is transferred and/or reflected within and
between layers or
segments of layers. By ordering layers within the module according to
increasing density, crush
strength and/or compressive strengths, and decreasing thickness, and
positioning the layers of
increasing density, crush strength and/or compressive strengths, and
decreasing thickness,
maximally distal to its predecessor in the specified crush sequence in the
module, a preferential
crush sequence of layers is created in the module. Note that successive panels
are placed
preferentially maximally distal from their predecessor but may also be placed
distal or adjacent to
their predecessor as required.
The variation in physical properties of layers may also be achieved by varying
the structural
properties of the individual honeycomb or foam core or panels, c~.g., the
material used, core
thickness, cell diameter, cell wall thickness, length of cell, presence of
facing sheet, facing sheet
material and thickness, and pre-crushing of honeycomb panels. Additionally,
the successively
increasing density, crush and/or compressive strengths in layers positioned
adjacent, distal or
maximally distal from their predecessor in the module are mathematically
related to one another to
produce an exponential, power, mufti-phase linear or logarithmic; shaped load
versus deflection
response of varying orders. Ultimately, the load versus deflection response
will determine the
deceleration of the incident body that characterizes its attenuation.
CA 02422415 2003-03-07
14
Thus, in an exemplary module of the present invention, a first layer of least
compressive and/or
crush strength and maximum thickness is positioned maximally distal from the
impacting object in
an exemplary module so as to load and partially compress or crush interceding
layers and
preferentially partially or fully crush the layer of least compressive and/or
crush strength and
maximum thickness. A second layer of next greater compressive and/or crush
strength and next
lesser thickness with respect to the first layer is positioned preferably
maximally distal in an
exemplary module to the first layer of least compressive and/or crush strength
and maximum
thickness in the module so as to load and partially compress or crush
interceding layers and
preferentially partially or fully crush the second layer of next greater
compressive and/or crush
strength and next lesser thickness. A third layer of next greater compressive
and/or crush strength
and next lesser thickness with respect to the second layer is positioned
preferably maximally distal
in an exemplary module to the second layer of next greater compressive andlor
crush strength and
next thinner thickness so as to load and partially compress or crush
interceding layers and
preferentially partially or fully crush the third layer of next greater
compressive and/or crush
strength and next lesser thickness. Generally a minimum of a three layer
module of total thickness T
is required for the inventive concept to demonstrate a significant increase in
efficiency over a single
layer energy absorbing article of similar or equivalent thickness T, though
any number of layers
greater than one can be used by extension of the inventive concept. For
example, in an exemplary 4
layer module, a fourth layer of next greater compressive and/or crush strength
and next lesser
thickness with respect to the third layer is positioned preferably maximally
distal in the module to
the third layer of next greater compressive and/or crush strength and next
thinner thickness so as to
load and partially compress or crush interceding layers and preferentially
partially or fully crush the
fourth layer of next greater compressive andlor crush strength and next lesser
thickness. And in an
exemplary five layer module, a fifth layer of next greater compressive and/or
crush strength and
next lesser thickness with respect to the fourth layer is positioned
preferably maximally distal in the
module to the fourth layer of next greater compressive and/or crash strength
and next thinner
thickness so as to load and partially compress or crush interceding layers and
preferentially partially
or fully crush the fifth layer of next greater compressive and/or crush
strength and next lesser
thickness. Note that as layers partially or fully compress, some layers may
need be positioned
adjacent or distal to one another rather than maximally distal to the
predecessing layer in the crush
sequence. In this manner, a compound load (stress) versus deflection (strain)
function is produced,
for example in basic terms an exponentially shaped function, in which the
resulting load or stress
CA 02422415 2003-03-07
results from the characteristics of the layer being crushed or compressed and
the loading and
compression of interceding layers.
While in basic terms the compound response may be mufti-phase liner, power,
logarithmic or
exponentially-shaped, a compound exponentially-shaped load versus deflection
response and
absorption of impact energy is advantageous because energy absorption and
deceleration is
relatively low initially in impact dynamics when kinetic energy is high and
progressively and
exponentially greater as kinetic energy of the impacting object is reduced.
This function is
consistent with the relationship of kinetic energy being related to the square
of the speed. That is, a
mufti-phase exponentially-shaped load (stress) versus deflection (strain)
response of an appropriate
order to an impacting object not only absorbs impact energy bui:
advantageously attenuates the
impact in a manner that cushions the impact by progressively and exponentially
decelerating the
impacting object more quickly as its kinetic energy is being reduced. It is an
object ofthe present
invention to describe a mufti-phase response produced by an enf;rgy absorbing
article comprising
multiple layers of energy absorbing materials of different physical properties
such as thickness,
density, compressive and crush strengths of total thickness T which is more
efficient and effective
in absorbing impact energy than a single layer, single density article of
equal thickness T. This will
allow for enhanced performance from an energy absorbing article of similar or
equivalent thickness,
or similar or equivalent performance from an energy absorbing article that is
thinner or lighter.
Note that while honeycomb generally crushes at constant crush strength
regardless of load
depending on its physical characteristics such as density and cell size for
the bulk of its deflection,
resilient foam generally has a stress versus percent strain response of
steadily increasing slope as
percent strain increases that may vary on static or dynamic compression. If
the stress versus strain
response is considered in basic terms to be of four discrete segments, i.e., a
first segment from 0-25
percent strain, a second segment from 26-50 percent strain, a third segment
from 51-75 percent
strain, and a fourth segment from 76-100 percent strain, then each layer of a
mufti-layer energy
absorbing and impact attenuating module could be considered to comprise four
compressive or
crush segments. Thus, segments of layers may also be positioned according to
increasing crush
and/or compressive strengths such that segments of layers are positioned
preferentially maximally
distal from their predecessor in the module and are tnathematica:lly related
to one another to produce
an exponential, power, mufti-phase linear or logarithmic shaped load versus
deflection response of
varying orders. For example, in an exemplary three layer modules of the
present invention as
CA 02422415 2003-03-07
16
described above, a first segment of a second layer is positioned maximally
distal from a first
segment of a first layer and of compressive and/or crush strength such that
the stress wave may
propagate, load, deflect or transfer energy through the interceding third
layer and preferentially
crushes before a second segment of the first layer. Likewise, a second segment
of the second layer
is positioned maximally distal from a second segment of the first layer and of
compressive andlor
crush strength such that the stress wave may propagate, load, deflect or
transfer energy through the
interceding third layer and preferentially crushes before a third segment of
layer one. The inventive
concept is extended to further segments and layers of the module.
Due to the variety of impact energies possible in the aspects of the present
invention, e.g., greater
than approximately 300 g (300 times the force of gravity) in impact dynamics,
the energy absorbing
and impact attenuating module of the present invention has several different
energy absorbing
layers and thus phases of energy absorption and impact attenuation in which
the impact absorbing
properties are not too hard for low energy impacts nor exhausted or perfectly
crushed upon high or
extreme impact energies relative to single layer or single density honeycomb
or foam articles. The
energy absorption and impact attenuation response may be advantageously
designed to be
synergistic with respect to the energy absorbing characteristics of the
impacting body, if applicable,
thereby creating a maximum summative response representing energy absorbing
components of
both the incident body and impacted body. For example, the compressive
strength of each of the
honeycomb panels in an energy absorbing and impact attenuating barrier for
motor sports can be
designed to be synergistic with the impact absorbing crumple zones of the
impacting racecar (e.g.
wheel and suspension components) producing not only a mufti-phase energy
absorbing and impact
attenuating response, but also a mufti-phase energy absorbing and impact
attenuating response that
is synergistic with the energy absorbing and impact attenuating n~esponse of
the racecar. Likewise,
the compressive strength of each of the foam layers in an energy absorbing and
impact attenuating
module used in a racecar head rest or cockpit surround can be designed to be
synergistic with the
impact absorbing characteristics of the helmet that will impact it producing
not only a mufti-phase
energy absorbing and impact attenuating response, but also a mufti-phase
energy absorbing and
impact attenuating response that is synergistic with the energy absorbing and
impact attenuating
response of the impacting helmet.
The more efficient energy absorbing and impact attenuating modules of this
invention may be
manufactured by a variety of processes and of materials classified as rigid
and plastic, e.g.,
CA 02422415 2003-03-07
l~
aluminum or aluminum foam, in which only a single impact is required to be
accommodated, or
elastic, viscoelastic, or elastomeric materials, e.g., thermoplastic
elastomers or viscoelastic foams,
of moderated or controlled rebound where multiple impacts are required to be
accommodated.
Advantageously, the embodiments of the mufti-phase energy absorbing and impact
attenuating
modules described herein also provide for mufti-phase energy absorption and
impact attenuation of
multiple impacts with a limited "dead time" when utilizing materials that
deform elastically. Due to
the unpredictable nature of collisions involving incident bodies such as
racecars or automobiles, or
in sporting events, it is not inconceivable that an impact with a rnulti-phase
energy absorbing and
impact attenuating module would be the only impact in the course of an
uncontrolled accident, but
rather it possible that another collision could impact the same portion of the
mufti-phase energy
absorbing and impact attenuating module before it be repaired o~r replaced.
Utilizing elastic,
elastomeric or viscoelastic materials that return to their original morphology
within a minimum
dead time, that is the time the mufti-phase energy absorbing and impact
attenuating module
structures require to return from a crushed, deformed or compressed state to a
sufficiently energy
absorbing and impact attenuating state and provide a specified percentage of
their original multi-
phase energy absorbing and impact attenuating properties, allows for
accommodation of multiple
impacts.
Traffic and Safety Barriers.
In the first aspect of this invention, this invention relates to traffic
barriers used to absorb and
attenuate the impact energy of racecars colliding with barrier systems that
define the limits of race
tracks including, but not limited to, oval, tri-oval, speedway, super
speedway, temporary street
circuits, road racing courses, drag racing or any combination of the former.
The mufti-impact,
mufti-phase energy absorbing and impact attenuating barrier system of this
invention is installed in
intimate association with and in a prescribed alignment with existing concrete
barrier systems
thereby interacting with incident colliding racecars 'From a multi~hzde of
incident angles and in a
multitude of orientations to absorb energy and attenuate the impact of the
racecar thereby
decreasing the peak force of impact in multiples of the force of gravity ~g
force) and increasing the
time as measured in milliseconds over which the peak g force is exerted
thereby reducing injury to
the racecar driver and damage to the incident colliding racecar. 'lf'lhese
factors are particularly
significant in collisions between a racecar and an energy absorbing and impact
attenuating barrier
CA 02422415 2003-03-07
1~
system because the length of time that impact energy is dissipated as measured
in milliseconds is an
important characteristic of the barrier system.
Automobile racing tracks require a barrier that defines the outer limits of
the race track to prevent
racecars from leaving the racing surface, and to contain any debris from the
normal course of the
racing event or racing collisions which occur during the racing event within
the confines of the race
track. Automobile racing tracks also require a barrier that defines a
spectator area physically
separate and remote from the racetrack to provide a safe envirorunent for
spectators. A necessary
and increasingly important characteristic of this type of barrier that has
emerged as raeecar speeds
have increased is that it must have some degree of energy absorbing and impact
attenuating
properties to minimize physical damage to racecars and racing drivers upon
collision with the
barrier.
Historically, a number of devices have been utilized primarily for the purpose
of defining the outer
limits of the racing surface or track and defining a remote spectator area -
devices such as hay
bales, dirt beans, wooden and metal railings, concrete abutments, wire fencing
or combinations of
the above. In particular, steel fencing, such as Armco, and concrete
abutments, such as concrete
barriers with a rectangular surface parallel to and in a vertical orientation
to the racetrack and
attached wire containment fencing, serve as barriers commonly utilized in
European and North
American automobile racing events respectively. Concrete barrier systems have
become
commonplace in North American racing because they are modular, not dislodged
or damaged after
an impact with an incident racecar, do not require repair within or between
racing events, and have
no associated parts that may be dislodged during the collision that cause a
danger to other racing
vehicles, drivers or spectators.
However, while the latter barrier systems serve well to define the outer
limits of the racetrack and
contain ordinary or extraordinary racing debris, they do so by providing a
fixed, hard surface ('hard
wall'), and thus do not have any significant energy absorbing and impact
attenuating properties to
reduce peak impact forces and assist in preventing serious injury to a raging
driver or significant
damage to the racecar. The impact absorbing responsibility of such a collision
lies solely with the
racecar.
CA 02422415 2003-03-07
19
A commonplace and economical solution used in road racing applications is to
supplement the
existing racetrack barrier system, e.g., concrete barriers, metal barriers and
beans, with tire barriers
consisting of used automobile tires lying horizontally and bundled sevcral
tires high in adjoining
vertical columns, sometimes with a rigid tube placed in the tire .opening of
the vertical column, to
provide energy-absorbing characteristics (refer to Federation Internationale
de L'Autornobile
Standard 8861-2000, FIA Energy Absorbing Inserts for Formula ~ne, Tire
Barriers Standard).
These tire barriers are typically used in applications where the racetrack
barrier system is at a
distance from the racing surface itself such as may be the case in road racing
circuits, that is, where
a gravel trap or grass field intercedes between the racing surface and
racetrack barrier system.
However, tire barriers are not useful in applications where the racing surface
and barrier system are
immediately adjacent to one another because significant impacts with an
incident racecar during the
event can dislodge the tire barrier module itself or break the tire bundles
causing the dislodged tires
or associated hardware from the barrier to be a safety hazard to l:he racing
event.
Those skilled in the art have previously described energy absorbing or
attenuating elements in a
plurality of barrier modules manufactured of a variety of materials such as
metal, polymers or
rubber to be utilized for absorbing the impact of incident colliding vehicles
Yunick (1997, US Patent 5,645,368) described a racetrack consisting of barrier
modules including a
base mounted on the barrier support surface delineating two crash barrier
rings circumscribing the
racing surface with the inner ring in a juxtaposed relationship wiah the
racing surface. Yunick's
invention relates also to racetracks and their constn~ction, more particularly
to new vehicle
racetracks constructed with novel and improved crash barriers. However, the
novel barrier method
described by Yunick cannot be integrated easily, if at all, with existing
barner systems found at
existing racetracks.
Muller (1998, US Patent 5,851,005) described the use of hexagonal metal
elements to absorb
incident impacts, however the impact-absorbing capabilities of such a device
are exhausted after a
single severe impact and afford no further impact absorbing properties for
collisions that may occur
immediately after this first impact. Arthur (1999, US Patent 6,276,667)
described the use of
cylindrical elements of a rubber or polymer material that may reo:ain their
impact-absorbing
characteristics after an initial severe impact. Muller and Arthur .have both
chosen to align the impact
absorbing hexagonal or cylindrical elements such that the long axes are
parallel and longitudinal to
CA 02422415 2003-03-07
the vertical surface of the existing barrier rather than orthogonal. Such
alignment provides for only
limited collapse or compression of the elements as defined by the material,
and width of the
hexagonal or cylindrical elements. Moreover, longitudinal alignment of similar
hexagonal or
cylindrical elements does not provide for multiphase energy absorbing or
impact attenuating
characteristic s.
In the application of an energy absorbing and impact attenuating barrier
system for racing or other
vehicles, an energy absorbing material must have a controlled rebound
characteristic to prevent
impact energy from the collision being transferred back to the impacting body.
A controlled
rebound property of an energy absorbing and impact attenuating barrier system
is critical in
automobile racing because incident colliding racecars must have' as much
impact energy as possible
absorbed and dispersed throughout the honeycomb or foam structure yet have a
minimum of
rebound to prevent energy from being transferred back to the incident vehicle
causing either more
energy to be absorbed by the racecar structure or, in the case of a relatively
elastic collision, cause
the racecar to be propelled back into the race track, possibly into the path
of oncoming racing
traffic.
More recently, those skilled in the art have considered barriers whereby
materials of relatively low
density, for example, low, medium or high density foam, have been placed in
front of the existing
concrete barrier system to provide energy absorbing and impact attenuating
characteristics generally
known as 'soft wall' barriers. Due to the relatively low density of these
materials, however, a
significant depth of material is required to attenuate racing vehi<;les, thus
decreasing the overall
usable surface of the racetrack. Moreover, these materials are generally not
resilient and a single
impact may exhaust or significantly reduce the energy absorbing; and impact
attenuating
characteristics of such barriers. In addition, unless a combination of
materials of various densities is
utilized in the 'soft wall' barrier design, the energy absorbing and impact
attenuating properties of
such a system are also of a single phase owing to the single density energy-
absorbing medium.
Thermoset elastomers (TSE) consisting of cross-linked polymer chains have also
been considered
for 'soft wall' applications. Safari Associates, Inc. utilize a material
called MolecuthaneT"'~ for soft
wall applications in automobile racing. While TSE barriers may be designed
with suitable energy
absorbing and impact attenuating characteristics in their thickness direction,
and may provide multi-
CA 02422415 2003-03-07
21
phase absorption and attenuation due to layers of differing densities, they
may cause a 'pocketing'
response as described below and are also generally not recyclable as
thermoplastic elastomers
(TPE) are.
Other 'soft wall' barrier solutions such as sacrificial inertial barriers that
utilize frangible barriers
containing energy absorbing dispersible mass including sand and water (Pitch,
1999, US Patent
5,957,616) have been described. A single, severe impact with the frangible
barrier will not only
exhaust or significantly reduce its energy absorbing and impact attenuating
capabilities, but also
may contaminate the racing surface with the dispersed energy-absorbing
material.
However, 'soft wall' barrier solutions may result in a 'snagging" or
'pocketing' characteristic that
snags incident cars upon impact when they penetrate the relatively soft
materials thereby causing a
very fast deceleration of the incident car that in fact may cause significant
damage to the driver in
the collision of the car with the 'soft wall' due to the; pronounced
deceleration forces associated with
the 'pocketing' response.
A solution in prior art to the problems of 'soft walls' and 'pocketing'
responses is to use an
impenetrable outer surface to the barrier system such as high-density
polyethylene, guardrails or
rectangular metal tubing. The Indy Racing League (IRL) and Indianapolis Motor
Speedway (IMS)
installed a barrier system on the inside of Turn 4 in 1998 called the
Polyethylene Energy
Dissipating System (PEDS) utilizing 5-foot long overlapping, high density,
polyethylene impact
plates with two 16-inch diameter polyethylene cylinders bolted behind the
impact plates acting as
the energy absorbing medium. However, the high-density polyethylene impact
plates are not
sufficiently resilient when positioned on the outside of a curve to avoid
penetration and subsequent
'snagging' or 'pocketing' by an impacting racecar.
Pitch (1999, US Patent 5,921,702) describes displaceable highway safety
barrier system extending
along the side of a roadway that includes a number of skid assemblies resting
without attachment on
a supporting surface adjacent to the roadway. However, such displaceable
guardrail barriers require
many mounting and interface members and significant space requirements. Pitch
(2000, US Patent
6,010,275) also describes a compression guardrail including a rail extending
longitudinally along a
roadway with a plurality of fixed support posts spaced behind thf: rail and
resilient compressible
energy absorbing means mounted between the rail and the posts. However, in
both systems
CA 02422415 2003-03-07
22
described by Fitch, the barrier itself is a continuous, strong, impenetrable
surface and, while
bendable, as such is not easily displaceable or compressible, therefore not
providing an energy
absorbing or impact attenuating response as efficient as possible.
The Indy Racing League (IRL) and Indianapolis Motor Speedway (IMS) have
developed a barrier
system in conjunction with the Midwest Roadside Safety Facility at the
University of Nebraska -
Lincoln called the SAFER (Steel and Foam Energy Reduction) barrier that was
installed on the
outside of turns at IMS in the spring of 2002. The barrier consists of four
rectangular structural steel
tubes welded together forming sections, each section joined to the next by
heavy steel internal
splines. Bundles of 2-inch thick polystyrene sheets are placed between the
structural steel tube
barrier and the existing concrete barrier. The polystyrene bloclts comprise
several layers and may
utilize differing densities or thicknesses, however an integrated response and
crush sequence of
maximally distal layers is not specified.
An efficient racing safety barrier should resist breaking, avoid snagging of
incident vehicles or
racecars, bend or displace to absorb a significant amount of impact energy,
and redirect the incident
vehicle or racecar without bouncing it back across the traffic stream. Thus,
an object of an improved
energy absorbing and impact attenuating barrier is to utilize the .advantages
of a 'soft wall' system,
i.e., effective energy absorption due to the compression of an energy
absorbing medium or media,
with the advantages of a 'hard wall' barrier, i.e., without the inherent
detrimental 'pocketing'
response, yet provide for improved energy absorption by providing a more
bendable, displaceable
and compressible barrier system as compared to axed, continuous, 'hard wall'
systems such the IRL
SAFER system.
Accordingly, several objects and advantages of the mufti-impact, mufti-phase,
energy absorbing and
impact attenuating barrier system described herein are:
(a) the energy-absorbing characteristics of the barrier system are not
exhausted after a single impact
such as is the case in energy absorbing barrier systems utilizing a light
density crushable material
such as foam (Nelson, 1999,US Patent 5,860,762) or metal (Mul:ler, 1998, US
Patent 5,851,005)
that do not provide energy absorbing or impact attenuating characteristics for
a secondary incident
following the primary impact prior to repair being affected to said energy
absorbing barrier system.
CA 02422415 2003-03-07
23
(b) the mufti-layered panels of the barrier system provide for a specific
mufti-phase energy
absorbing and impact attenuating response that inherently absorbs an increased
amount of impact
energy due to the transfer of impact energy between layers within the module
as compared to the
energy absorbing capabilities of prior art.
(c) the barrier system is relatively compact and integrated easily with the
existing concrete barrier
system as compared to other 'soft wall' designs so as to be practical and
economical.
(d) the impact-absorbing and attenuating barrier system elements are fixed
with a minimum of
hardware to the existing concrete barrier system in a manner that prevents
elements from being
dislodged or damaged such that they or debris from them may be dangerous to
other drivers,
vehicles or spectators.
(e) there are no dispersible elements of the impact absorbing and attenuating
barrier system that will
interfere with the racing circuit or cause consequence to the race after
impact and consequent
rupture of the energy absorbing barrier such as is the case with frangible
barriers.
(f) the energy-absorbing characteristics of an energy absorbing and impact
attenuating barrier
system are mufti-phase due to different shapes, configurations, a.nd physical
dimensions of energy
absorbing components rather than providing a linear or single phase
attenuation due to the use of a
single material of consistent density, shape, configuration or physical
dimension.
(g) the energy absorbing and attenuating characteristics, becausf; they are
designed to be variable
and mufti-phase, may be 'tuned' or engineered to certain specifications to be
complementary and
synergistic with the impact absorbing characteristics of the racecar or
vehicle in use.
{h) the energy-absorbing and attenuating characteristics are designed such
that in relative terms, in
comparison to the existing concrete ('hard") barrier system, the :impact
absorbing and attenuating
barrier system is:
~ relatively 'hard' for crash energy below approximately 5 to 10 times the
multiple of the force
of gravity (5-10g) and the racing vehicle primarily absorbs the bulk of the
impact, thus not
CA 02422415 2003-03-07
24
sacrificing absorption characteristics of the wall for inconsequential
collisions, nor having 'soft'
portions of the wall that an incident racecar could interact with (e.g.,
puncture, get impeded by, get
caught up with) in highly oblique collisions. This may be achieved by means of
a sufficiently
resilient facing sheet or protective apron positioned in intimate contact and
in a prescribed fashion
external to the honeycomb module and facing incident colliding bodies.
~ relatively 'arm', yet progressively more energy absorbing and impact
attenuating for crash
energy between approximately 10 to 40 times the multiple of the force of
gravity ( 10-40g), and the
racing vehicle and said impact absorbing and attenuating barrier system share
in a synergistic
manner the impact energy of the crash,
~ relatively 'soft' for crash energy above approximately 40 times the multiple
of the force of
gravity (40g) and the impact absorbing and attenuating barrier system absorbs
a shared but
increasingly larger portion of the impact energy of the crash. In this
capacity, a mufti-phase energy
absorbing and impact attenuating response, e.g., logarithmic or f;xponential,
tuned to the incident
body, e.g., an open wheel racecar, becomes increasingly significant.
(i) the energy absorbing and attenuating elements of the impact absorbing and
attenuating
components can be easily reconfigured and 'tuned' for different applications
(e.g., open wheel
racecars, closed wheel racecars) without involving an altered process of
manufacture.
(j) that, where it is understood that the impact absorbing and attenuating
harrier system is not
required to be installed adjacent to the existing concrete barrier system
around the racetrack in its
entirety, that contoured end-piece components be designed and manufactured to
define the
beginning and end of the energy absorbing and impact attenuating barrier
system.
{k) the energy absorbing and attenuating barrier manufacturing process is well
known to those
skilled in the art and can be made of a materials familiar to those associated
with the racing and tire
industry thereby offering both an economical and practical advantage.
Further objects and advantages of the mufti-impact, mufti-phase energy
absorbing and impact
attenuating barrier system described herein are to provide an impact absorbing
and attenuating
CA 02422415 2003-03-07
barrier system in conjunction with existing concrete barrier systems that are
inert to environmental
forces, require a minimum of maintenance, and maintain a surface for other
previously defined
functions of the concrete barrier system, e.g. advertising.
Still further objects and advantages will become apparent from review and
consideration of the
ensuing description and drawings.
Automobile Bumper Assembly and System.
In the second aspect of this invention, this invention relates to a mufti-
phase energy absorbing and
impact attenuating core material for automobile bumper assemblies in which
said mufti-phase
energy absorbing and impact attenuating core material for an automobile bumper
assembly is an
integrated component of an automobile bumper system comprising a compound
energy absorbing
and impact attenuating response involving the bumper assembly and vehicle
energy absorbing
crumple zones of the chassis or unit body.
It is well known that automobiles may sustain front and rear impacts of
varying energies during
routine operation. The use of front and rear automobile bumpers in automobiles
in North America
was mandated in 1925. Automobile bumpers generally serve two fianctions, one,
to provide the
esthetic function of extending downward the front and back bodywork of the
vehicle with
continuity to its overall shape, and, two, to perform the mechanical fun<;tion
of absorbing impacts of
a variety of energies that the vehicle may sustain.
Those skilled in the art have devised methods involving metal bumpers, metal
bumpers augmented
by hydraulic or mechanical dampers, tubes, profiles or honeycomb structures.
According to Glance
(US Patent 5799991, 1998) most contemporary automobile bumper systems consist
of three basic
components, a bumper beam, a bumper absorber, and a cover or fascia. The
bumper beam is often
metal, the bumper absorber is commonly a shock absorbing device or a
polypropylene foam block,
and the fascia is typically molded from a urethane plastic. Recently,
thermoplastic elastomers (TPE)
and thermoplastic polyolefins (TPO) have been used to manufacture molded,
deformable, glass mat
reinforced bumpers. Tusim et al. (2001, US Patent 6,213,540) describes an
energy absorbing article
of extruded thermoplastic foam that exhibits anisotropic compressive strength
for use in light
weight plastic automobile energy absorbing units (EAU).
CA 02422415 2003-03-07
26
More recently, hybrid steel/thermoplastic TPO bumpers have been described for
lighter bumpers
resilient to small impacts. The use of elastomers in molded bumpers and bumper
fascias provides
great design flexibility, lighter weight, improved resistance to impacts and
corrosion, and the ability
to recycle old or damaged bumpers.
The required energy absorption capacity of an autormobile bumper directly
relates to the weight of
the vehicle, i.e., the heavier the vehicle, the higher the levels of energy
absorbing capacity are
required. Bumpers for light cars often utilize a metal or composite fiber
reinforced beam fixed to the
vehicle frame with a molded foam polypropylene energy absorbing block mounted
between the
beam and the fascia cover. Bumpers for heavy cars often utilize a metal or
composite fiber
reinforced beam mounted on hydraulic shock absorbing devices.
While many of these automobile bumper assemblies satisfy the requirements 2
miles per hour (4
kilometres per hour) and 5 miles per hour (8 kilometres per hour) impact
tests, they have
limitations. The energy absorbing and impact attenuating properties of
existing bumper assemblies
may not be sufficient for high impact energies thereby causing a. large
portion of the impact energy
to be transferred to the vehicle structure and thus the occupants of the
vehicle.
Occupant injuries can be reduced if a greater amount of impact .energy is
isolated from the vehicle
chassis or unit body structure, and if the impact energy is absorbed by the
bumper assembly and
vehicle chassis or unit body structure in an integrated manner to prevent
abrupt changes in impact
dynamics. Impact energy is not generally absorbed in an integrated fashion by
the bumper assembly
and the energy absorbing crumple zones of the vehicle chassis or unit body
structure with which the
bumper assembly is in association with in prior art. This causes an abrupt
change in impact
dynamics in vehicles with bumper assemblies of prior art and causes a transfer
of a significant
amount of impact energy in an abrupt manner to the vehicle chassis or unit
body structure
potentially to the detriment of the driver and passengers.
Additionally, due to the primarily single-phase energy absorption and impact
attenuating
characteristics of energy absorbing cores of prior art, the only way to
increase the impact absorbing
capacity involves increasing the dimensions and/or masses of the energy
absorbing devices.
CA 02422415 2003-03-07
27
Advantageously, the mufti-phase energy absorbing and impact attenuating module
of the present
invention can be utilized as the absorber or core material of an automobile
bumper assembly with
the thickness direction of the honeycomb and/or foam module aligned generally
parallel and
longitudinal to the direction of front and rear impacts, i.e., parallel and
longitudinal to the length of
the vehicle. The individual panels or layers and overall energy absorbing
response of the module
may be tuned to the weight of the vehicle providing for a cost advantage by
means of the same
configuration of core material being used for light and heavy vehicles, but
with a variation in
structure creating appropriate energy absorbing and impact attenuating
properties specific to the
vehicle. The module may be contoured to the shape of the bumper to serve both
esthetic and impact
absorbing functions. The honeycomb and/or foam modules of this invention when
used as the
absorber or core material for automobile bumpers may be fused or bonded on the
one side to an
outer foam component associated with the bumper fascia to provide resilience
for multiple
inconsequential impacts, and on the other side, to the inner beam component of
the bumper, or be
aligned in intimate contact with the energy absorbing crumple zone structure
of the vehicle itself.
The load versus deflection response of the mufti-phase energy absorbing and
impact attenuating
module of the present invention module is designed with respect to weight of
the vehicle and
overall compressive and crush strengths of the front or rear crumple zones of
the vehicle chassis or
unit body or other vehicle structures with which it is in intimate association
with. The maximum
transfer of impact energy between layers within the mul ti-phase energy
absorbing and impact
attenuating module will isolate a greater amount of impact enerl;y from the
vehicle structure and
thus the occupants of the vehicle, thereby potentially reducing morbidity or
mortality of the vehicle
occupants. The mufti-impact capabilities of the mufti-phase energy absorbing
and impact
attenuating module utilized as a core material for bumper assemblies also
provides for energy
absorption of secondary impacts, for example, a rear impact from another
vehicle may cause the
impacted vehicle to careen out of control and collide with another body in the
same area impacted
by the primary impact.
Further advantages have been described in the other aspects of this invention.
Still further objects
and advantages will become apparent from review and consideration of the
ensuing descriptions and
drawings.
CA 02422415 2003-03-07
2~
Energy Absorbing Vehicle Structure.
In the third aspect of the present invention, this invention relates to a
mufti-phase energy absorbing
and impact attenuating module for a vehicle door, or other vehicle, cha:>sis,
cabin or cockpit energy
absorbing structure.
Automobile doors are constructed in a well-known manner typically comprising
an inner and outer
door panel. A decorative door trim panel is usually affixed to the inner door
panel.
It is well known that automobiles may sustain side or other imp;~cts of
~aarying energies that intrude
upon the cabin during their routine operation. Those knowledgeable in the art
have employed
various means to absorb the impact energy of a side collision with an
automobile to protect the
occupants from injury. Metal beams have been positioned in vehicle doors to
protect occupants
from side collisions but offered little energy absorbing characteristics. hoam
materials, egg crate or
cone shaped structures have been described whereby these articles are
positioned between the inner
and outer door panels to provide energy absorbing capabilities. :Elowever, the
space between the
inner and outer door panel is typically small and varying in width and is
intruded upon by various
mechanical components making it difficult for low density, single-phase energy
absorbing
structures to be effective for higher impact energies involved in automobile
collisions. More
recently, side impact air bags have been utilized to protect vehicle occupants
from side impacts, and
while effective, are relatively expensive both in initial installment and
repair.
Honeycomb has been described by those skilled in the art as an energy
absorbing material for
vehicle doors and other vehicle structures. Saathoff ( 1994, US Patent
5,306,066) whose assignee
was the Ford Motor Company described a honeycomb shaped energy absorbing
structure for
absorbing energy from a side collision type impact of the door vehicle.
Saathoff listed advantages of
his invention as being able to be tuned to meet side collision type impact
requirements, having the
honeycomb shaped energy absorbing structure precrushed to provide lower crush
strength, and
being light weight and low cost compared to conventional foam material and
cone shaped
structures. However, Saathoff claimed only a single layer honeycomb structure
made of precrushed
aluminum, thus of single phase, plastic response.
Wielinga (2000, US Patent 6,117,520) whose assigalee was AB Volvo (SE)
described a honeycomb
block useful as an impact force-absorbing element in a door of a vehicle
comprising three sections
CA 02422415 2003-03-07
2R
of cardboard honeycomb elements characterized in that the cell size of each
honeycomb element
section decreases from a large size in one section to a smaller si:ae in the
neighboring section and an
even smaller size in the third section facing inward with respect to the
passenger compartment of
the vehicle. While Wielinga claimed a mufti-layered honeycomb block that
provides for a gradually
hardened impact, he does not claim an embodiment that provides for a tuneable
energy absorbing
response, a preferred crush sequence or a means for maximizing the transfer of
impact energy
within the honeycomb block as described for the a mufti-phase energy absorbing
and impact
attenuating module for a vehicle door of this invention. While claiming a
progressively smaller cell
size from the outer to inner sections of the honeycomb block, there is no
consideration or relation of
compressive or crush strengths of individual layers claimed by '~Vielenga, nor
of an elastic response.
Advantageously, the mufti-phase energy absorbing and impact attenuating module
for a vehicle
door or other vehicle chassis or cabin structure of the present invention
provides improved energy
absorption due to the tunable and specified mufti-phase response in a limited
space described in the
previous aspects of this invention. The load versus deflection re sponse of
the module is designed to
be complementary or synergistic with respect to the overall corr.~pressive
strength of the door or
other vehicle chassis and cabin structures that it is in intimate association
with. In this application,
the controlled and moderated rebound characteristics of the honeycomb module
are not critical as in
the farst aspect of this invention, i.e., some energy from the collision may
be transferred back to the
impacting body. The multiphase energy absorbing and impact attenuating
honeycomb module of
this invention may also be utilized similarly in other vehicle chassis or
cabin structures such as the
firewall, dashboard, pillars, rear crumple zone and passenger safety cell..
Head injury of drivers and occupants is also a problem in vehicles and
racecars. Road-going
vehicles generally have energy absorbing foam materials positioned to
intercede in an impact
between the head or other body parts of the driver or occupant and a vehicle
chassis structure, for
example, dashboards and cabin pillars. Cockpit surrounds and head rests
comprised of energy
absorbent foams are generally utilized in racecars as well to attempt to
miniz~ize head injury. These
safety features are typically limited in the thickness of energy absorbing
material due to design
constraints. With such limitations, the more efficient the capacity of the
energy absorbing
honeycomb and foam materials, the more effective the energy absorbing
capability will be given the
same thickness of material. Advantageously, the more efficient mufti-layer
energy absorbing and
CA 02422415 2003-03-07
impact attenuating modules of the present invention provide enhanced
performance without
increasing the thickness of energy absorbing material.
Further advantages have been described in the other aspects of this invention.
Still further objects
and advantages will become apparent from review and consideration of the
ensuing descriptions and
drawings.
Crash, Sports and Recreational Helmets.
In yet another aspect of this invention, this invention relates to a mufti-
impact, mufti-phase energy
absorbing and impact attenuating component of protective or safety equipment,
e.g., liners for
protective clothing, articles, and equipment, and sports and crash helmets.
Protective clothing,
articles and equipment such as shin pads, gloves, and shoulder pads are used
in contact sports such
as football and hockey to protect the wearer from injury. Sports and Brash
helmets are used by
persons engaging in sporting, recreational and work activities in which they
are exposed to a risk of
head injury. Protective clothing, articles, equipment and helmets. of prior
art generally comprise a
hard outer shell that serves to diffuse, distribute and absorb impact energy,
an inner liner that further
absorbs the energy of the impact and cushions (i.e., attenuates) the impact
sufficiently to protect the
wearer from injury, comfort or sizing pads, and a retention system that
maintains the protective
device appropriately on the wearer's body.
Improvements on existing sports and crash helmet designs may be made by
utilizing the more
efficient mufti-phase energy absorbing and impact attenuating nodules of the
present invention
described herein to offer improved performance, for example improved energy
absorbing capacity
with the same or similar physical dimensions of prior art, or similar or
equivalent performance as
compared to prior art with lighter and/or thinner energy absorbing liners.
Additionally, the inner
liner and hard outer shell may be treated as integral components of a mufti-
layer energy absorbing
module to further enhance its energy absorbing capability.
Crash Helmets.
Drivers and passengers of motorcycles, cars and other vehicles involved in
racing events are
exposed to a high risk of head injury and are generally required to wear a
crash helmet meeting
specified standards.
CA 02422415 2003-03-07
31
Generally, a crash helmet requires a strong, shatterproof outer shell and an
inner liner that dissipates
energy and cushions the head from sharp impacts to the shell, thereby
protecting the head and brain
from linear and rotational impact energy. The outer shell is substantially
spheroidal in shape and
typically consists of an injectior~molded thermoplastic or pressure-molded
thermoset reinforced
with fibres. In prior art, the inner foam liner is commonly polystyrene, but
may be polyurethane
foam. The crash helmet absorbs impact energy when the outer shell bends and
the underlying foam
deforms. The foam inner liner can generally compress by approximately 90
percent during an
impact, thus provided cushioning of a blow to the head. However, if the
maximum strain exceeds
the approximate 90 percent compression, then the foam becomes effectively
solid and linear and
rotational impact energy will be transmitted to the head.
Typically, the energy absorbing capability of the foam inner lirner of crash
helmets of prior art is
limited by having single density foam of limited thickness. As tlhe single
layer foam liner
approaches complete crushing due to the impact, it no longer absorbs impact
energy causing an
abrupt change in impact absorption dynamics, causing transfer of impact energy
to the head thereby
potentially causing morbidity and mortality. Additionally, the energy
absorbing response of the
inner liner and outer shell of crash helmets of prior are not well integrated,
that is, the compressive
strength and energy absorbing characteristics of the foam liner and shell do
not form an integrated,
compound response which minimizes abrupt changes between phases of impact
dynamics. In the
case of a crash helmet, thickness and density of the shell and liner must be
limited as increased
helmet mass and size can add to angular inertia of the head increasing risk of
neck injury and
helmet roll off
Advantageously, the mufti-phase energy absorbing and impact attenuating module
of the present
invention can be utilized to form a mufti-layer crash helmet liner which
provides improved energy
absorption with the same total thickness and weight compared t~o single layer
foam liners, or
thinner, lighter liners with similar or equivalent performance. In particular,
an exemplary
embodiment of this invention in the aspect of a crash helmet involves multiple
layers of foam of
differing densities positioned intimately adjacent to one another in the inner
liner, with the inner
liner in intimate association with the outer shell, the outer shell being
consistent with prior art or
comprising an inner and outer facing sheet of substantially a spheroidal shape
with a honeycomb
core integrated between the facing sheets.
CA 02422415 2003-03-07
32
The outer shell is manufactured by a variety of processes, for example
injection or pressure molding
of a thermoplastic or thermoset material. Advantageously the c~~mpressive
strengths of the inner
liner foam layers and outer shell of the crash helmet of this inventive
concept are designed relative
to one another such that the impact is firstly diffused, dispersed and
absorbed partially by the outer
shell, then by a successive crush sequence of the foam layers of differing
physical properties such as
density and thickness of the inner liner while minimizing changes in impact
dynamics between
layers and phases of impact absorption by formang an integrated, compound,
exponentially-shaped
stress (load) versus strain (deflection) response. The layers are positioned
such that successive
layers according to density, thickness and/or compressive strengths are
positioned preferentially
maximally distal, but also distal or adjacent where required, from one another
in the crush sequence.
Sports/Recreational Helmets.
Head injury remains a significant cause of morbidity and mortality in
sporting, recreational and
work activities.
Sports and recreational helmets generally fall into one of three categories.
1. Helmets generally comprising a hard outer shell of a thermoplastic
material, an energy-absorbing
inner liner of expanded polystyrene (EPS) or expanded polypropylene (EPP) or
similar material,
and comfort or sizing pads of flexible foam.
2. Helmets comprising an EPS, EPP or similar layer and comfort or sizing pads
of flexible foam
with no outer shell.
3. Helmets comprising an EPS, EPP or similar layer and comfort or sizing pads
of flexible foam
with a thin outer microshell of thermoplastic material.
EPS liners are generally rigid, inelastic and permanently deform on impact and
thus are useful only
for single impacts. EPP liners are sufficiently elastic to accommodate
multiple impacts. Flexible and
viscoelastic foams are also generally sufficiently elastic to accommodate
multiple impacts
Mendoza (United States patent Application 20020023291) describes a safety
helmet constructed of
layers of polyurethane, monoprene gel, polyethylene and either :polycarbonate
or polypropylene. An
alternate embodiment is described in which multiple layers of impact absorbing
inner layers of two,
three or more different densities may be utilized. However, there is no
description or claims relating
to crush sequence, positioning or relative thickness of layers, or an
integrated, compound response.
CA 02422415 2003-03-07
33
Moore, III (United States Patent 6,453,476) describes a protective helmet
which preferably has a
hard outer shell and an energy absorbing liner made of low resilience or slow-
recovery foam which
is compression rate sensitive. Moore claims a liner with a first, second and
third portion of
viscoelastic polymeric foam, each portion of which has a different stiffness.
Moore claims the first,
second and third foams as positioned adjacent to one another in different
portions of the helmet
rather than layering the foams however. While this configuration allows for
three different
compressive strengths in three different portions of the helmet liner, the
different portions are not
layered and do not create a mufti-phase response in a specific portion of the
helmet liner.
Halstead, et al. (Unites States Patent 6,434,755) describes a helmet with a
one-piece first shock
attenuating member positioned adjacent to and substantially in contact with
portions of the inner
surface of the shell, and a plurality of second shock attenuating members
positioned adjacent to
portions of the first shock attenuating member and adjacent to and
substantially in contact with
portions of the inner surface of the shell. Each second shock attenuating
member has a second
thickness and second density, the second density of which is greater than the
first thickness and the
second compression deflection being less than the first compression
deflection. The second shock
attenuating members, being thicker and of less compression deflection than the
first shock
attenuating member, firstly compress on impact by the head, compressing until
the thickness of the
first shock attenuating member. However, the first shock attenuating member
being preferably
constructed of expanded polypropylene (EPP) does not substantially compress
and the second shock
attenuating members do not further contribute significantly to the energy
absorption of the impact.
Thus, while the response of the helmet liner described by Halstead, et al. is
mufti-phase, a number
of layers greater than two is not claimed, the layers are positioned adjacent
to one another rather
than built up on one another, compression of the layers being successive does
not cause a secondary
absorption of impact energy by loading energy absorbing layers positioned
between successive
layers of the crush sequence, and an optimal compound responsf; is not claimed
in which absorption
of impact energy is relatively low initially in impact dynamics when kinetic
energy is high and
progressively greater as kinetic energy of the impacting object is reduced.
Ewing, et al. (United States Patent Application 20020184699, United States
Patent 6,425,141 )
described a helmet with a rigid outer shell and three energy-absorbing layers
made of two types of
open-celled polyurethane foams. The first layer adjacent to the rigid shell
and inner-most layer are a
CA 02422415 2003-03-07
34
CONFOR TM CF-40 yellow foam while the middle layer is a CONFOR TM CF-47 green
foam, the
middle layer of which is of greater stiffness than the first and imler-most
layers. Swing claims at
least three energy absorbing layers positioned with respect to one another
such that a layer of low
dynamic impedance is adjacent to layer of high dynamic impedance, thus
comprising alternating
layers of energy absorbing materials having different dynamic i~npedances.
Swing describes the
multiple layering of materials having different stiffnesses as causing a
reflection of propagating
stress waves through the materials, ultimately absorbing larger amounts of
energy than the same
materials not layered with alternating stiffness could absorb. Swing does not
describe or claim the
loading of, or transfer of energy through, or maximizing the distance of
stress wave propagation by
layers positioned between successive layers of the crush sequen<;e positioned
maximally distal from
one another as a secondary energy absorption characteristic enhancing the
energy absorbing
response. Swing claims alternating layers of high and low impedance rather
than successive layers
in the crush sequence positioned preferably maximally distal to one another.
Swing does not claim a
different thickness for each layer related to its density or comprf;ssivc
strength thereby causing a
compound exponentially- or logarithmic-shaped compound response of varying
orders. Thus, while
Swing describes a mufti-phase response with a secondary energy absorption
characteristic his
claims do not optimize this response.
Additionally, none of the inventions of prior art have considered or claimed
the use of thin, pliable
facing sheets at the common boundary surface where a layer of thickness,
density and compression
strength is positioned adjacent to another layer of the same or differing
thickness, density and
compression strength to further distribute and dissipate impact energy from
one layer to another.
Inventions of prior art also do not consider the compressive strength of the
hard, outer liner as an
integral component of a mufti-layer energy absorbing system thereby not
minimizing the abrupt
change in impact dynamics that may occur as energy is transferred from the
outer shell to the inner
liner or vice versa.
Further advantages have been described in the other aspects of this invention.
The above discussed
and many other features, objects and advantages of the present invention will
be better understood
by reference to the following detailed description and accompanying drawings.
CA 02422415 2003-03-07
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Multi-phase Energy Absorbing and Impact Attenuating Traffic and Safety
Barriers.
Referring now to the ensuing diagrams, a mufti-phase energy absorbing and
impact attenuating
module 10 is shown generally in FIG. 1 wherein said module is a component of
an impact-
absorbing barrier for racecars or highway barriers comprising several panels,
each panel of which
comprises a honeycomb or foam core with or without a facing sheet or sheets,
each core of which
comprises a plurality of honeycomb or foam cells. An exemplary five-layer
honeycomb module is
shown generally in FIG. 2, FIG. 3 and FIG. 4 wherein said module is a
component of an impact-
absorbing barrier for racecars or highway barriers. The exemplary five-layer
honeycomb module
comprises honeycomb panels 1 l, 12, 13, 14, 15 and facing sheets 31, 32, 33,
34, 35. The
honeycomb module is described as a uniform build-up type in which the panels
are of the same
length and width. It will be understood that the modules of the present
invention may also be of the
pyramid build up type in which the panel or panels facing the incident body
are of a smaller length
and width than the back panels facing the receiving body producing a pyramidal
build up of panels
in the module.
An exemplary honeycomb core is shown generally at 12 in FIG. 5. The honeycomb
has a length
(L), a width (W) and a thickness (T). It will be understood that t:he same
convention of physical
dimensions applies to foam core structures or articles. It will be also
understood that the exemplary
honeycomb 12 is one of multiple honeycomb, modified honeycomb or honeycomb-
like cores or
foam cores or articles in the mufti-phase energy absorbing and impact
attenuating module 10
positioned to intercede in an impact between an incident body of variable mass
and energy colliding
with a receiving body of variable mass and energy so used to not only absorb
the impact energy of
the incident body but also attenuate it in a controlled and specified fashion.
It will be further
understood that the honeycomb core may be comprised of true honeycomb cells,
honeycomb-like
cells, over-expanded or under-expanded cells, or modified honeycomb cells and
that the honeycomb
or foam core may be manufactured of a variety of materials generally
classified as rigid, elastic,
viscoelastic, plastic, polymeric, elastomeric or fibre reinforced elastomeric
by processes including
molding, extrusion, expansion and corrugation. Where mufti-impact energy
absorbing and impact
attenuating modules are desired, it will be understood that elastic,
viscoelastic or elastomeric
materials will be utilized. While an exemplary module of five honeycomb,
modified honeycomb or
CA 02422415 2003-03-07
3C
honeycomb-like panels is described, any number of honeycomb, modified
honeycomb, honeycomb-
like or foam cores, panels or articles greater than one may be used in the
exemplary embodiment.
Several exemplary honeycomb cells 21, 22, 23, 24, 25 are shown in FIG. 6 with
cell diameter (CD),
cell wall thickness (CWT), and cell length (CL) identified. It will be
understood that cells 21, 22,
23, 24, 25 may represent true honeycomb cells, honeycomb-like cells, over-
expanded or under-
expanded cells, or modified honeycomb cells and a:re repeated numerous times
throughout each
honeycomb, modified honeycomb or honeycomb-like panel. However, the cell type
will be
consistent in each individual honeycomb, modified honeycomb or honeycomb-like
panel, and the
density consistent in each foam core panel.
It will be understood that in general terms foam structures and articles have
isotropic energy
absorbing properties, though cross-linked polymer foams may have relatively
superior energy
absorption capacity in directions other than the T direction. Thus, while the
exemplary module
described comprises multiple layers of honeycomb panels, it will be understood
that foam layers or
articles may also be utilized in one or more layers of the mufti-phase energy
absorbing and impact
attenuating modules of the present invention.
Facing sheets 3 l, 32 are shown generally in FIG. 7 as fused, bonded or
otherwise fixed to the
exemplary honeycomb core 12. The exemplary honeycomb panel 13 is generally
considered to be
comprised of honeycomb core 12 and facing sheets 31, 32. It will be understood
that facing sheets
31, 32 are fused, bonded or otherwise fixed to adjoining honeycomb 11 and
honeycomb 13 to form
multiple layers of honeycomb panels in the mufti-impact, mufti-phase energy
absorbing and impact
attenuating module 10. Honeycomb 1 l, which is directed towards impacting
bodies, may or may
not have a facing sheet fused or bonded to its outermost surface impacted
firstly by an incident
body, and is shown generally in FIG.1 as not having a facing shE:et fused or
bonded to its innermost
surface. Honeycomb I 1 may also be replaced by a foam core of cross-linked
polymer construction.
Referring again to FIG. 3 and FIG. 4, the facing sheet 33 is fused, bonded or
otherwise fixed to
adjoining honeycomb 13 and honeycomb 14, facing sheet 34 is fused, bonded or
otherwise fixed to
adjoining honeycomb 14 and honeycomb 15, facing sheet 35 is fused, bonded or
otherwise fixed to
honeycomb 15 towards the receiving body thus forming multiple: layers of
honeycomb panels in the
mufti-phase energy absorbing and impact attenuating module la. While impact
energy is dispersed
from cell to cell in the honeycomb or foam matrix through cells with adjoining
cell walls, the
CA 02422415 2003-03-07
37
presence of facing sheets serves to further dissipate the impact load in two
ways, one by further
dissipating the impact energy along the front facing sheet facing the impact
to non-impacted cells,
and two, by further dissipating impact energy along the back facing sheet and
to cells in the
adjacent layer once the affected cells in the layer have fully compressed
under the impact.
The whole honeycomb module 10 is generally constrained by a containment
structure at the front,
back, top, bottom and either sides of the honeycomb module to prevent the
honeycomb or foam
cores, panels or articles from being significantly displaced or crashed,
compressed or deformed in a
direction non-parallel with the T direction. In some instances, the
containment of the honeycomb
module 10 will be structures other than the specified containment structure
that the honeycomb
module is in intimate association with, e.g., the bottom being the road, the
back being the existing
concrete barrier, the sides being adjoining honeycomb modules and the front
and top being a
protective apron in the aspect of the present invention described for use as a
mufti-phase energy
absorbing and impact attenuating barrier system for use with racecars and
automobiles.
Each honeycomb panel 11, 12, 13, 14, 15 has specified crush, bare and
stabilized compressive
strengths based on the honeycomb core material, cell diameter (CD) of
honeycomb cores 1 l, 12, 13,
14, 15, cell wall thickness (CWT) of honeycomb cores 11, 12, 13, 14, 15, cell
length (CL) of
honeycomb cores 11, 12, 13, 14, 15, and facing sheet 31, 32, 33., 34, 35
material and thickness. It
will be understood that anisotropic foam cores or articles also have specified
compressive and crush
strengths based on the type and density of the core material.
In FIG. 8, an exemplary relative load versus deflection response graph is
depicted representing the
uniform and plastic or elastic deformation of an exemplary noirprecrushed
honeycomb panel when
loaded. The bare compressive strength 51 is shown. The crush strength 52 of
the exemplary
honeycomb is also indicated and is less than the bare compressive strength 51.
Note that when the
honeycomb or foam core has perfectly crushed, i.e., it has maximally crushed,
compressed or
deformed (the deflection approaches the thickness T), it effectively becomes
solid and no further
significant deflection can occur to absorb impact energy. It is vitally
important that energy
absorbing structures do not perfectly compress before the impact energy of a
collision is
significantly reduced because a significant amount of the impact energy can be
transferred back to
the incident body in an abrupt manner adversely affecting the impact absorbing
dynamics of the
energy absorbing and impact attenuating system. The use of mufti-layer energy
absorbing modules
CA 02422415 2003-03-07
38
with progressively increasing crush strength will reduce the likelihood of
perfect crushing of the
whole module and thus provide for a gradually increasing attenuation and more
effectively absorb
the impact energy of a collision.
In FIG. 9, an exemplary relative load versus deflection graph is depicted
representing the uniform
and plastic or elastic deformation of an exemplary precrushed honeycomb when
loaded. Crush
strength 57 is shown. Note that there is no bare compressive load peak
required when the exemplary
honeycomb is in the precrushed state before it deforms. Once again, when
deflection approaches the
thickness T, the crush strength rises dramatically and abruptly as the energy
absorbing material
effectively becomes a solid.
The exemplary mufti-phase energy absorbing and impact attenuating module 10 is
generally shown
in FIG. l, FIG. 2, FIG. 3 and FIG. 4 as comprising multiple layers of linear
honeycomb panels. The
layers may also be slightly contoured to accommodate the curvature of the
receiving body, e.g.,
concrete barriers positioned in corners of the racetrack. The number of layers
of honeycomb or
foam cores, panels or articles of the modules of this inventiomnay be any
number greater than one,
but must conform to a specified crush sequence based on positie~n of the core,
panel or article within
the module, the relative and absolute bare, stabilized or crush strengths, and
the state of the core,
panel or article being either precrushed or non-precrushed. The exemplary
mufti-phase energy
absorbing and impact attenuating module 10 is produced wherein honeycomb
panels 11, 12, 13, 14,
15 are positioned in a specific configuration according to relative crush,
bare and stabilized
compressive strengths as well as precrushed or norr~precrushed states such
that in the preferred
embodiment the honeycomb panels will sequentially crush upon. impact: in the
order of 1 l, 15, 12,
14, 13 to maximize transfer of impact energy between layers within the
exemplary mufti-phase
energy absorbing and impact attenuating module 10. That is, in the crush
sequence specified above
in an exemplary honeycomb module in the preferred embodiment comprising five
honeycomb
panels 1 l, 12, 13, 14, 15, impact energy will be firstly absorbed by the
crushing of the honeycomb
panel 11 least resistant to the load and subsequently be transferred
internally through the other
layers of the honeycomb module to the maximally distal norrcmshed honeycomb
panel. In the
preferred embodiment, after honeycomb panel 11 is fully compressed, honeycomb
panel 15 will be
next least resistant to the impact load as it is the notrcrushed honeycomb
panel maximally distal
from honeycomb panel 11. By placing honeycomb panels 12, 13, 14 in a non-
precrushed state and
of greater compressive or crush strength between the honeycomb panel 11 first
fully crushed and
CA 02422415 2003-03-07
39
the successive honeycomb panel 15 in the crush sequence according to relative
bare, stabilized or
crush strengths in the preferred embodiment, further energy from the impact
can be absorbed by
applying loads from transferred impact energy through the non-precrushed
panels 12, 13, 14,
thereby providing for a secondary energy absorption capability by causing some
impact energy to
be absorbed in the partial loading or pre-crushing of honeycomb panels 12, 13,
14. Advantageously
then, impact energy transferred from honeycomb panel to succe;~sive adjacent,
distal or maximally
distal honeycomb panel in the crush sequence in the preferred elnbodirnent is
also dissipated by
utilizing the transferred energy to load and partially pre-crush the
successive honeycomb panels in
the crush sequence. Note that the crush sequence of layers to achieve this
secondary energy
absorption capability may be a variable, e.g. 1 l, 15, 13, 14, 12, lbut that
it does not simply involve
successive layers as is the case in a crush sequence of layers 1 l, 12, 13,
14, 15, in that order. Note
also that an alternate embodiment in which layer 11 is positioned adjacent the
concrete barrier, layer
12 is positioned to face incident traffic, layer 13 is positioned adjacent on
the inside (towards the
race track) of layer 1 l, layer 14 is positioned adjacent on the outside
(towards the concrete barrier)
of layer 12, with layer 15 being the middle layer may further optimize the
energy absorbing
capacity of the mufti-phase energy absorbing and impact attenuating module 10
by maximizing the
distance of propagation of the stress wave of impact energy.
In an exemplary embodiment, honeycomb panel 11 of the exemplary honeycomb
module 10 least
resistant to impact energy is positioned to face incident collidin~; bodies
and is firstly impacted by
an incident body. Honeycomb panel 11 need not have a facing sheet on the side
of the honeycomb
core facing the incident colliding objects. Instead, a protective structure,
i.e., an apron 55, of metal,
plastic or other material may intercede between the honeycomb module 10,
specifically honeycomb
panel 1 l, and the incident colliding object. In an alternative embodiment,
honeycomb panel 11 may
have a facing sheet fused, bonded or othea-wise fixed to the side of the
honeycomb core facing the
incident colliding objects, also serving as a protective structure i:or the
honeycomb module. In a
third embodiment of this aspect, honeycomb panel 11 ma y have both a facing
sheet fused, bonded
or otherwise fixed to the side of the honeycomb core facing the :incident
colliding objects, and a
protective structure of metal, plastic or other such material that intercedes
between the honeycomb
module 10, specifically honeycomb panel 11, and the incident colliding object
to serve as a more
substantial protective structure for the honeycomb module. Note that the
combination of said
protective structure and/or facing sheet must be sufficiently elastic to allow
for the exemplary
energy absorbing module 10 to react in its designed fashion.
CA 02422415 2003-03-07
4(1
Referring again to the exemplary embodiment of the exemplary honeycomb module
10 in FIG. 1,
FIG. 2, FIG. 3, and FIG. 4 depicting an exemplary mufti-phase energy absorbing
and impact
attenuating module comprised of five linear honeycomb panels, and the relative
load versus
deflection graph in FIG. I l, honeycomb panel 11 is in a precrushed state and
has a crush strength
CS I 1 less than that of honeycomb panel 15 located maximally distal from
honeycomb panel 11.
Honeycomb panel 15 is in a precrushed state and has crush strength CS15
greater than CS1 I, but
less than that of honeycomb panels 12, 13, and 14. Honeycomb panel I 5 is
located maximally distal
from honeycomb panel 11. After high or extreme impact energy of greater than
CS 11, affected cells
of honeycomb panel 11 will plastically or elastically deform and crush until
the honeycomb core 11
is fully crushed and compressed. Once fully crushed, the affected cells of
honeycomb panel 11
demonstrate no further deflection effectively becoming solid and are in a dead
response time such
that the energy from the impact is preferentially transferred through the
honeycomb module from
honeycomb panel 11 to honeycomb panel 15. After receiving sufficient impact
energy of greater
than CS15, cells of honeycomb panel 15 will plastically or elastically deform
and crush until fully
crushed or compressed. Once fully crushed, the affected cells of honeycomb
panel 15 demonstrate
no further deflection effectively becoming solid and are in a dead response
time such that the
energy from the impact is preferentially transferred through the honeycomb
module from
honeycomb panel 15 to honeycomb panel I2. Honeycomb panel I2 is in a non
precrushed state and
has a crush strength CS 12 greater than C S 1 S, but less than that of
honeycomb panel 14 located
maximally distal from honeycomb panel 12 allowing for the fact that honeycomb
panels I l and 15
have plastically deformed, crushed fully, and are in a dead response time.
Cells of honeycomb panel
12 will have been partially loaded and in a partially loaded or precrushed
state subsequent to the
transfer of impact energy from honeycomb panel 11 to honeycomb panel 15. After
receiving
sufficient impact energy of greater than stabilized campressive strength SCS
12, cells of honeycomb
panel 12 will plastically or elastically deform and crush until fully crushed
and compressed. Once
fully crushed, the affected cells of honeycomb panel 12 demonstrate no further
deflection
effectively becoming solid and are in a dead response time such that the
energy from the impact is
preferentially transferred through the honeycomb module from honeycomb panel
12 to honeycomb
panel 14. Honeycomb panel 14 is in a non precrushed state and has a crush
strength CS 14 greater
than CS 12, but less than that of honeycomb panel 13. Honeycomb panel 14 will
be in a partially
loaded or precrushed state subsequent to loading from impact energy
transferred from honeycomb
panel 11 to honeycomb panel 15, and honeycomb panel 15 to honeycomb panel 12.
After receiving
CA 02422415 2003-03-07
41
sufficient impact energy of greater than stabilized compressive strength
SCS14, cells of honeycomb
panel 14 will plastically or elastically deform and crush until fully crushed
or compressed. Once
fully crushed, the affected cells of honeycomb panel 14 demonstrates no
further deflection
effectively becoming solid and are in a dead response time such that the
energy from the impact is
preferentially transferred through the honeycomb module from honeycomb panel
14 to honeycomb
panel 13. Honeycomb panel 13 is in a nomprecrushed state and has crush
strength greater than
CS 14, but less than the crush strength of the backing material with which it
is in intimate
association with, e.g., a concrete barrier of crush strength CSCo in the
embodiment described for
use as a mufti-phase energy absorbing and impact attenuating barrier system
for use with racecars
and automobiles. After receiving sufficient impact energy of grf;ater than
stabilized compressive
strength SCS13, cells of honeycomb panel 13 will plastically or elastically
deform and crush until
fully crushed and compressed. Once fully crushed, the affected cells of
honeycomb panel 13
demonstrate no further deflection effectively becoming solid and are in a dead
response time and
the maximum energy absorbing and impact attenuating properties of the
honeycomb module have
been realized. If elastic materials have been utilized, the honeycomb module
as a whole is then in a
dead time mode for a short duration of time until the cores, panels or
articles recover their original
shape and size. Note that this exemplary description is for illustrative
purposes of the concept the
present invention and that the relative crush and compressive strengths,
precrushed or non-
precrushed states, and crush sequence of panels within the module may be
altered and thus tuned
specifically to an application.
Generally, in the exemplary embodiment, the core thickness T 1 l and cell
length of honeycomb
panel 11 CL 11 is greater than that of honeycomb panel 15, the core thickness
T 15 and cell length of
honeycomb panel 15 CL15 is greater than that of honeycomb panel 12, the core
thickness T12 and
cell length of honeycomb panel 12 CL 12 is greater than that of honeycomb
panel 14, and the core
thickness T 14 and cell length of honeycomb panel 14 CL 14 is greater than
that of honeycomb panel
13 resulting in an approximation of an exponential shaped response as depicted
in FIG. 11. Note
that by altering the relative thickness of the cores of honeycomb. panels,
e.g.,
T11<T15<T12<T14<T15, different load versus deflection responses may be
achieved, e.g., an
approximation of a logarithmic-shaped response can be achiever as depicted in
FIG. 13. The load
versus deflection response depicted in FIG. 11 will decelerate the incident
object relatively slowly
at first, then progressively more quickly as the impact energy is absorbed and
reduced due to the
collision of the incident body with the first layer or layers of the module.
Such a response will
CA 02422415 2003-03-07
42
provide controlled, tunable attenuation and more gradual absorption or
cushioning response to the
incident body.
Generally, in the exemplary embodiment, the cell diameter CD 11 of honeycomb
panel 11 is greater
than the cell diameter CD 15 of honeycomb panel 15, the cell diameter CD 15 of
honeycomb panel
15 is greater than the cell diameter CD 12 of honeycomb panel 12, the cell
diameter CD 12 of
honeycomb panel 12 is greater than the cell diameter CD I4 of honeycomb panel
14, and the cell
diameter CD 14 of honeycomb panel 14 is greater than the cell diameter CD 13
of honeycomb panel
13. Note that by altering the relative cell diameters of the cells of the
honeycomb panels different
responses may be achieved. Additionally, in the exemplary embodiment, the cell
wall thickness
CWTl 1 of honeycomb panel 11 is less than the cell wall thicknc;ss CW'T15 of
honeycomb panel 15,
the cell wall thickness CWT15 of honeycomb panel 15 is less than the cell wall
thickness CWT12
of honeycomb panel 12, the cell wall thickness CWT 12 of honeycomb panel 12 is
less than the cell
wall thickness CWTI4 of honeycomb panel 14, and the cell wall thickness CWT14
of honeycomb
panel 14 is less than the cell wall thickness CWT13 of honeycomb panel 13.
Note that by altering
the relative thickness of the cell walls of the cells of honeycomb panels,
different responses may be
achieved.
Generally then, in the exemplary embodiment, the successive crush sequence of
the honeycomb
panels in the exemplary honeycomb module upon impact is honeycomb panel 11,
honeycomb panel
15, honeycomb panel I2, honeycomb panel I4, and finally honeycomb panel 13.
FIG. 11
demonstrates the individual relative load versus deflection resp~~nse for the
exemplary honeycomb
module 10 comprising five layers of honeycomb panels relative to one another
and superimposed
on the same horizontal axis in the order of successive crush sequence. FIG. 12
demonstrates an
approximate exponential-shaped relative load versus deflection response graph
for the exemplary
honeycomb module 10 considering that the transferred impact energy from one
honeycomb panel to
another will also serve to load the successive non-precrushed honeycomb panels
superimposed on
the same horizontal axis in the order of successive crush sequence.
FIG. 13 demonstrates an approximate logarithmic-shaped relative load versus
deflection response
graph for the exemplary honeycomb module 10 considering that the transferred
impact energy from
an individual honeycomb panel will also serve to load the successive
norrprecrushed honeycomb
panel superimposed on the same horizontal axis in the order of successive
crush sequence. FIG. 13
CA 02422415 2003-03-07
43
demonstrates an approximate exponentially-shaped relative load versus
deflection response graph
for the exemplary honeycomb module 10 achieved by varying core thickness, cell
diameter and cell
wall thickness of layers in the module considering that the transfverred
impact energy from an
individual honeycomb panel will also serve to load the successive non
precrushed honeycomb panel
superimposed on the same horizontal axis in the order of successive crush
sequence. Note that the
load versus deflection response of FIG. 13 will quickly decelerate the
incident object upon impact
with the first layer or layers of the module and then decelerate it more
slowly as the impact energy
is absorbed and reduced.
FIG. 1 l, FIG. 12, and FIG. 13 demonstrate that the resultant relative load
versus deflection curve
and thus deceleration response to the incident body for the exemplary
honeycomb module 10 can
thus be tuned by nature of the core thickness, successive crush and
compressive strengths, and crush
sequence of the honeycomb panels of the honeycomb module. In some instances,
an approximation
of a logarithmic-shaped response may be most appropriate for a specific
application, while in others
an exponential or mufti-phase linear response may be most appropriate. The
relative crush strengths,
bare and stabilized compressive strengths of the exemplary honeycomb panels
may be modified by
cell length, cell diameter, cell wall thickness for a given honeycomb core
material or by material
and density of a foam core. The absolute compressive and crush strengths are
designed with respect
to expected impact energies and energy absorbing properties of the incident
body. In all aspects of
the present invention though the resultant load versus deflection response and
thus deceleration
response is designed to attenuate the impact of either the incident body.,
receiving body or both. For
example, in the aspect of the present invention wherein said mufti-phase
energy absorbing and
impact attenuating modules are an impact absorbing barrier for racecars, the
racecar (incident body)
must be decelerated upon impact with the barrier (receiving body) in such a
manner so as to
minimize damage and injury. This may require an exponential-shaped
deceleration versus distance
response in which the racecar is initially decelerated relatively slowly while
at high speed in the
initial phase of the impact, and more quickly decelerated in later phases of
the impact after some
impact energy has been absorbed.
FIG. 14 illustrates an exemplary mufti-impact, mufti-phase energy absorbing
and impact attenuating
module in the preferred embodiment wherein said module is a mufti-phase energy
absorbing and
impact attenuating barrier for use with racecars and automobiles capable of
decelerating on impact a
racing or other vehicle of very high speed over an extended period of time as
measured in
CA 02422415 2003-03-07
44
milliseconds at a significantly reduced multiple of the force of gravity (g-
force) as compared to
existing concrete barriers thereby reducing the primary, secondary or tertiary
impact gforce per
unit millisecond. The barrier system is relatively compact and integrated
easily by quick release
fasteners 58 at 57 with the existing concrete barrier 51 as compared to other
'soft wall' designs so
as to be practical and economical. The barrier system elements are fixed with
a minimum of
hardware 58 to the existing concrete barrier system 51 in a manner that
prevents elements from
being dislodged or damaged such that they or debris from them :may be
dangerous to other drivers,
vehicles or spectators. A protective apron 55 maintains the mufti-impact,
mufti-phase energy
absorbing and impact attenuating module 10 in intimate association and in a
prescribed alignment
with the existing concrete barrier 10, such that the "T" direction of the
module is orthogonal to the
vertical surface of the existing concrete barrier, and also prevents lateral,
vertical or horizontal
displacement of module I0. The protective apron is substantially a reverse c-
type configuration and
is fixed and integrated with adjacent outer wall components in an overlapping
fashion accounting
for rotation or direction of racecars on the racetrack, consists of a smooth,
hard outer surface of
appropriate longitudinal strength that will not bind significantly with a
rotating race tire, and has an
easement 56 along its inferior portion to assist with clearing track debris.
Upon impact by an incident racecar or vehicle, the incident body will firstly
impact the protective
apron 55 causing the impacted area to plastically or elastically deform
inwardly towards the module
10. The impacted area of the protective apron will be displaced into the
adjacent layer 11 of the
module 10. The module 10 will then behave as previously described herein to
absorb the energy of
the impact and attenuate the racecar or vehicle such that it decelerates in a
prescribed fashion.
The mufti-phase energy absorbing and impact attenuating module 10 is designed
to be sufficiently
resilient to accommodate multiple impacts, and if damaged, is designed to be
replaced in short
period of time as defined by 'yellow flag' caution periods during a racing
event.
Mufti-phase Energy Absorbing and Impact Attenuating Vehicle Bumper System.
Referring now to FIG. 15, FIG. 16 and FIG. 17, an automobile bumper assembly
is shown generally
at 61. It is known that automobile bumper assemblies of prior aht consist of a
bumper beam 62, core
63 and fascia 64 and that the bumper core 63 is primarily responsible for
providing energy
absorption from incident bodies. The bumper beam 62 is often metal, the bumper
core or absorber
CA 02422415 2003-03-07
63 is commonly a shock absorbing device or a polypropylene foam block, and the
fascia 64 is
typically molded from a urethane plastic.
The required energy absorption capacity of an automobile bumper assembly 61
directly relates to
the weight of the vehicle. While many of automobile bumper systems satisfy 2
miles per hour (4
kilometres per hour) and 5 miles per hour (8 kilometres per hour) impact
tests, they have
limitations. The energy absorbing and impact attenuating properties of
existing bumper assemblies
may not be sufficient for high impact energies thereby causing a, large
portion of the impact energy
to be transferred to the vehicle structure and thus the occupants of the
vehicle. The only way to
increase the impact absorbing capacity of the bumper assembly involves
increasing the dimensions,
density and masses of the energy absorbing devices.
Advantageously, the mufti-phase energy absorbing and impact attenuating module
10 of this
invention can be utilized as the core of an automobile bumper assembly with
the thickness direction
of the honeycomb and/or foam layers aligned generally parallel and
longitudinal to the direction of
front and rear impacts, i.e., paralle.l and longitudinal to the length of the
vehicle. The mufti-phase
energy absorbing and impact attenuating module 10 is contoured to the shape of
the bumper
assembly 61 to serve both esthetic and impact absorbing functions. Referring
to FIG. 17, the multi-
phase energy absorbing and impact attenuating modules of the present invention
when used as the
core 10 for an automobile bumper assembly 61 may be fused or bonded on the one
side to an outer
foam component 63 associated with the bumper fascia 64 to provide resilience
for multiple
inconsequential impacts, and on the other side, to the inner beam 62 of the
bumper assembly, or be
aligned in intimate contact with the energy absorbing crumple zone structure
of the vehicle chassis
or unit body itself 68.
The load (stress) versus deflection (strain) response of the mufti-phase
energy absorbing and impact
attenuating module 10 is designed with respect to the weight of the vehicle
and overall compressive
and crush strengths of the front or rear crumple zones 68 of the vehicle or
other vehicle structures
with which it is in intimate association with to form an energy absorbing
vehicle bumper system
comprising an integrated response. In an exemplary embodiment of the present
invention in which
the mufti-phase energy absorbing and impact attenuating module 10 is
positioned in intimate
association with a portion of the energy absorbing crumple zone structure 68
of the vehicle chassis
or unit body designed specifically to accommodate the mufti-phase energy
absorbing and impact
CA 02422415 2003-03-07
46
attenuating module 10 of the bumper assembly 61, the compressive and crush
strength of the
bumper fascia 64 is least, the foam core 63 is of greater compressive and
crush strength, the layers
of the mufti-phase energy absorbing and impact attenuating module 10
positioned in an exemplary
manner maximally distal from their predecessor in the crush sequence have
increasing compressive
and crush strength in the order of layers 1 I, 15, 12, 14, 13, with the layer
13 of greatest corrq~ressive
and crush strength of the mufti-phase energy absorbing and impact attenuating
module I O being less
than the initial compressive strength of the energy absorbing emmple zone
structure of the vehicle
chassis or unit body 68. In the exemplary embodiment, layer 11 is positioned
nearest the energy
absorbing crumple zone structure 68 of the vehicle chassis or unit body, layer
15 positioned
adjacent to the foam core 63, layer 12 positioned adjacent layer I 1 facing
the foam core 63, layer 14
positioned adjacent layer 15 facing the energy absorbing crump:Le zone
structure 68 of the vehicle
chassis or unit body, and layer I3 positioned in the middle. In the exemplary
embodiment, layer 11
is the thickest, layer 15 next thickest, layer 12 next thickest, layer 14 next
thickest and layer 13 least
thick. In the exemplary embodiment, layer I 1 has the least density and
compressive strength, layer
15 next greatest density and compressive strength, layer 12 next: greatest
density and compressive
strength, layer 14 next greatest density and compressive strength and layer 13
the greatest density
and compressive strength.
In another exemplary embodiment, the metal bumper beam 62 is included and is
positioned to
intercede between the mufti-phase energy absorbing and impact attenuating
module 10 and the
energy absorbing crumple zone structure of the vehicle chassis or unit body 68
so used to further
disperse and distribute impact energy not absorbed by the bumper of the
present invention to the
energy absorbing crumple zone structure of the vehicle chassis or unit body
68. The metal bumper
beam 62 is designed with appropriate shear strength and stiffness to function
as a facing sheet
which preferentially deforms after the energy absorbing capability of the
bumper assembly 61 of the
present invention has crushed significantly prior to and concurrent with the
transfer of energy to the
energy absorbing crumple zone structure of the vehicle chassis or unit body 68
to further absorb
impact energy.
Thus, in a front or rear impact with a vehicle having the bumper assembly and
system of the present
invention the impact dynamics arc such that the bumper fascia 64 will firstly
be impacted. As the
fascia 64 is fully or partially compressed or Brushed, impact energy will be
transferred to the foam
core 63 interceding between the module 10 and the fascia 64. As the foam core
63 fully or partially
CA 02422415 2003-03-07
47
compresses or crushes, impact energy will be transferred to the multi-phase
energy absorbing and
impact attenuating module 10, which will advantageously provide enhanced
energy absorption by
means of the crush sequence of layers positioned preferably maximally distal
to their successor in
the crush sequence. That is, impact energy and forces Load the mufti-phase
energy absorbing and
impact attenuating module 10 such that the layer least resistive to the impact
energy and forces will
compress firstly. Thus, although the stress wave of impact energy will
propagate through, load and
partially compress interceding layers 15, 14, 13 and 12, layer 11. maximally
distal to the impact will
preferentially partially or fully crush. Layer 15 next least resistive to the
impact energy and force
located maximally distal from layer 11 will compress partially or fully next
preferentially causing
propagation of the stress wave of impact energy to travel a maximum amount and
load and partially
compress interceding layers 12, 13 and 14. Subsequently, the stress wave of
impact energy will
propagate to the next least resistive layer 12 positioned maximally distal
from layer 15 so as to fully
or partially crush it and load and partially crush interceding layers 14 and
13. Subsequently, the
stress wave of impact energy will propagate to the next least resistive layer
14 positioned maximally
distal from layer 12 so as to fully or partially crush it and load and
partially crush interceding layer
13, which will partially or fully crush lastly.
As the mufti-phase energy absorbing and impact attenuating module 1Q is
partially or fully
compressed or crushed, impact energy will be transferred to the energy
absorbing crumple zone
structure of the vehicle chassis or unit body 68 if the mufti-phase energy
absorbing and impact
attenuating module 10 is in intimate contact with the energy absorbing crumple
zone structure of the
vehicle chassis or unit body 68, or bumper beam 62, if included, which will
fully or partially crush
or deform serving to further absorb or distribute impact energy. The bumper
beam 62, if included,
will compress or deform the energy absorbing crumple zone structure of the
vehicle chassis or unit
body 68.
The compound response of each of the components of the vehicle bumper system
of the present
invention axe designed to form a compound exponentially-shaped response of an
order of which the
preferential crush sequence serves to attenuate the impact energy and minimize
abrupt changes in
impact dynamics. An exemplary simplified compound exponentially-shaped
response is shown in
FIG. 18.
CA 02422415 2003-03-07
48
Mufti-phase Energy Absorbing and Impact Attenuating Vehicle Safety Structures.
Vehicle safety structures such as vehicle cabin interior padding (for example
dashboard, steering
wheel and cabin pillar padding) and energy absorbing units in door panels
serve to reduce injury
during road and racing vehicle operation and collisions.
Door Panels.
Refernng now to FIG. 19 and FIG. 20, a vehicle door 71 is depicted
illustrating exemplary multi-
phase energy absorbing and impact attenuating modules 10 wherein said modules
are for use within
a vehicle door or other vehicle chassis structure. The outer door panel 71,
inner door panel 72 and
interior trim panel 73 are shown. In a side collision with the vehicle, the
incident body will firstly
impact the outer door panel 71 having a compressive and crush strength causing
it to plastically
deform inwardly towards the driver or passenger of the vehicle. Subsequently,
the inner door panel
72 having compressive and crush strength will be impacted causing it to
plastically deform inwardly
towards the driver or passenger of the vehicle. In an exemplary embodiment of
the present
invention, the mufti-phase energy absorbing and impact attenuating module 10
is positioned
between the inner door panel 72 and interior trim panel 73 to intercede in an
impact of sufficient
energy such that the outer door panel 71 and inner door panel 72 are
sufficiently displaced to impact
the driver or occupant 74.
The compressive and crush strengths and overall response of the mufti-phase
energy absorbing and
impact attenuating modules 10 are designed in relation to the compressive and
crush strengths of the
inner and outer door panels. Thus, in a side impact with a vehicle having the
mufti-phase energy
absorbing and impact attenuating modules 10 positioned in association with the
inner door panel 72
and interior trim panel 73 of the present invention, the impact dynamics are
such that the outer door
panel 71 will firstly be impacted. If the outer door panel 71 is displaced
sufficiently to impact the
inner door panel 72, impact energy will be transferred to the inner door panel
72. If the impact
energy is sufficient to cause displacement of the inner door panel 72 to
impact the driver or
occupant 74, impact energy will be absorbed by the mufti-phase; energy
absorbing and impact
attenuating module 10, which will advantageously provide enhanced energy
absorption by means of
the crush sequence of layers positioned preferably maximally distal to their
successor in the crush
sequence. That is, impact energy and forces load the mufti-phase energy
absorbing and impact
attenuating module 10 such that the layer least resistive to the impact energy
and forces will
compress firstly. Thus, although the stress wave of impact energy will
propagate through, load and
CA 02422415 2003-03-07
49
partially compress interceding layers 15, 14, 13 and 12, layer 11 maximally
distal to the impact and
adjacent the driver or passenger 74 will preferentially partially or fully
crush. Layer 1 S next least
resistive to the impact energy and force located maximally distal from layer
11 will compress
partially or fully next preferentially causing propagation of the stress wave
of impact energy to
travel a maximum amount and load and partially compress interceding layers 12,
13 and 14.
Subsequently, the stress wave of impact energy will propagate to the next
least resistive layer 12
positioned maximally distal from layer 15 so as to fully or partially crush it
and load and partially
crush interceding layers 14 and 13. Subsequently, the stress wave of impact
energy will propagate
to the next least resistive layer 14 positioned maximally distal from layer 12
so as to fully or
partially crush it and load and partially crush interceding layer 13, which
will partially or fully crush
lastly.
As the mufti-phase energy absorbing and impact attenuating module 10 is
partially or fully
compressed or crushed, impact energy will be absorbed so as to reduce injury
to the driver or
occupant 74. In the exemplary embodiment, the greatest crush and compressive
strengths of the
mufti-phase energy absorbing and impact attenuating module 10 is less than the
compressive or
crush strengths of the outer door panel 71 and inner door panel 72. In the
exemplary embodiment,
layer 11 is the thickest, layer 15 next thickest, layer 12 next thickest,
layer 14 next thickest and layer
13 least thick. In the exemplary embodiment, layer 11 has the least density
and compressive
strength, layer 15 next greatest density and compressive strength, layer 12
next greatest density and
compressive strength, layer 14 next greatest density and compressive strength
and layer 13 the
greatest density and compressive strength.
The compound response of each of the components of the of the present
invention are designed to
form a compound exponentially-shaped response of an order of which the
preferential crush
sequence serves to attenuate the impact energy and minimize abrupt changes in
impact dynamics.
An exemplary simplified compound exponentially-shaped response is shown in
FIG. xx.
Racecar Headrests and Cockpit Surrounds.
Racing vehicles also utilize energy absorbing structures to reduce injury
during racing vehicle
operation and collisions. In 1996, in an effort to reduce driver injury, the
Federation Internationale
d'Automobile {FIA) implemented improvements far driver safety including foam
padding around
the sides and rear of the cockpit opening. In side and rear impacts this foam
padded head rest and
CA 02422415 2003-03-07
cockpit surround serve to restrain the head, provide controlled deceleration
and prevent head
displacement and rotation that could potentially damage the neck. Head rests
and cockpit surrounds
are now used in many racecars to reduce the likelihood and extent of head
injury.
FIG. 21 depicts the cockpit surround 120 and head rest 109 of prior art for an
open wheel racecar.
According to specifications for Championship Auto Racing Teams (CART)
racecars, the area
behind the driver's helmet 80 must be constructed to minimize the effects of
neck and/or head
injuries in case of impact. The head rest I09, exclusive of padding, is
designed to deflect not more
than 2.0 inches rearward when a force of 200 pounds is applied. Including the
seat back and
continuing upward, the surface facing the helmet I25 must be continuous and
without gaps.
Contours must not prevent the torso I 1 l and neck/head 1 I2 from moving as a
single unit during
impact. Under no circumstances shall sharp or protruding objects which could
contact the helmet 98
be allowed as a part of the headrest 109 or cackpit surround 120 nor shall
such objects be positioned
forward of a vertical projection of this surface. The head rest 109 and
cockpit surround 120 shall be
located as close as practical to the helmet 80 when the driver's head 112 is
in the normal operating
position and surfaces shall be designed to reduce point loading upon contact
with the helmet and
should be designed in conjunction with the seat back 108 to allow acceleration
of the thorax, spine
and head together as a unit. Padding of high hysteresis foam 121 of the
following minimum
dimensions must be fitted in the areas of most probable helmet contact to
minimize injury in case of
impact:
Thickness - 2.0 inches minimum.
Height - extend from the base of the driver helmet with the driver seated in a
normal driving
position to within 6.5 inches of the top of the main rollover hoop.
Width - at least 7.0 inches wide at 10.00 inches from the top of the main
rollover hoop. Whenever
possible the contact area shall be perpendicular to the chassis reference
plane. Foam must be
covered to prevent environmental degradation.
FIG. 22 depicts the mufti-phase energy absorbing and impact attenuating module
10 of the present
invention are used in head rest 109 and cockpit surround 120 in place of a
single foam layer 121 of
prior art. An exemplary five layer mufti-phase energy absorbing and impact
attenuating module 10
is shown of same total thickness, e.g., 2 inches, as the single layer foam 121
of the head rest 109
and cockpit surround 120 of prior art and made generally of layers of energy
absoxbing materials
such as elastic foam, viscoelastic foam, and honeycomb. Two embodiments are
depicted.
CA 02422415 2003-03-07
51
In FIG. 22A, an embodiment is depicted that protects the driver from an
intrusive impact, for
example, a racecar impacting the driver's racecar perpendicular to the
driver's capsule. The layers
of energy absorbing materials are positioned such that the Layer 125 with the
least compressive
and/or crush strength is closest to the helmet 98 of the driver, the layer 126
of next greatest
compressive and/or crush strength is adjacent to the chassis or monocoque of
the racecar, the layer
127 of next greatest compressive andlor crush strength is positioned adjacent
layer 125 towards the
chassis or monocoque of the racecar, the Layer 128 of next greatest
compressive and/or crush
strength is positioned adjacent layer 126 towards the driver, and the layer
129 of next greatest
compressive and/or crush strength is positioned in the middle of the five
layer module. In the
exemplary embodiment, layer 129 is of greatest density, layer 128 next
densest, layer 127 next
dense, layer 126 next dense and layer 125 least dense of the layers. On an
intrusive impact in which
the monocoque or chassis structure 130 of the car intrudes into the driver
capsule, impact energy
displaces the racecar structure 130 towards and contacting the driver,
compressing the mufti-phase
energy absorbing and imp act attenuating module 10 as it does so. Impact
energy and forces load the
mufti-phase energy absorbing and impact attenuating module 10 such that the
layer least resistive to
the impact energy and forces will compress partially or fully frstly. Thus,
although the stress wave
of impact energy will propagate through, load and partially compress
interceding layers 126, 128,
129 and 127, layer 125 maximally distal to the impact will prefE;rentially
partially or fully crush.
Layer 126 next least resistive to the impact energy and force located
maximally distal from layer
125 will compress partially or fully next preferentially causing propagation
of the stress wave of
impact energy to travel a maximum amount and load and partially compress
interceding layers 127,
129 and 128. Subsequently, the stress wave of impact energy will propagate to
the next least
resistive layer 127 positioned maximally distal from layer 126 so as to fully
or partially crush it and
load and partially crush interceding layers 128 and 129. Subsequently, the
stress wave of impact
energy will propagate to the next least resistive layer 128 positioned
maximally distal from layer
127 so as to fully or partially crush it and load and partially crush
interceding layers 129, which will
fully or partially crush lastly. In the exemplary embodiment, layer 125 is
thickest, layer 126 next
thickest, layer 127, next thickest, layer 120 next thickest and layer 129 is
the least thick of the layers
creating a compound exponentially shaped response of an appropriate order to
cushion the driver
from the intrusive impact.
CA 02422415 2003-03-07
52
In FIG. 22B, an embodiment is depicted that protects the driver from a
decelerative impact, for
example, a racecar impacting with a concrete barrier. The layers of energy
absorbing materials are
positioned such that the layer 125 with the least compressive and/or crush
strength is adjacent to the
chassis or monocoque of the racecar, the layer 126 of next greatest
compressive and/or crush
strength is closest to the helmet of the driver, the layer 127 of next
greatest compressive and/or
crush strength is positioned adjacent layer 125 towards the driver, the layer
128 of next greatest
compressive and/or crush strength is positioned adjacent layer I26 towards the
chassis or
monocoque of the racecar, and the layer 129 of next greatest compressive
and/or crush strength is
positioned in the middle of the five layer module. In the exemplary
embodiment, layer 129 is of
greatest density, layer 128 next densest, layer 127 next dense, layer 126 next
dense and layer 125
least dense of the layers. On a decelerative impact in which the rnonocoque or
chassis structure 130
of the car impacts an object such as a concrete barrier, the drive:r's body
and head are forced against
the racecar structure 130 compressing the mufti-phase energy absorbing and
impact attenuating
module 10 as it does so. Impact energy and forces load the mufti-phase energy
absorbing and
impact attenuating module 10 such that the layer least resistive to the impact
energy and forces will
compress firstly. Thus, although the stress wave of impact energy will
propagate through, load and
partially compress interceding layers I26, I28, 129 and 127, layer I25
maximally distal to the
impact will preferentially partially or fully crush. Layer 126 next least
resistive to the impact energy
and force located maximally distal from layer 125 will partially or fully
crush next preferentially
causing propagation of the stress wave of impact energy to travel a maximum
amount and load and
partially compress interceding layers 127, 129 and 128. Subsequently, the
stress wave of impact
energy will propagate to the next least resistive layer 127 positioned
maximally distal from layer
126 so as to fully or partially crush it and load and partially crush
interceding layers 128 and 129.
Subsequently, the stress wave of impact energy will propagate to the next
least resistive layer 128
positioned maximally distal from layer 127 so as to fully or partially crush
it and load and partially
crush interceding layers 129, which will partially or fully crush lastly. In
the exemplary
embodiment, layer 125 is thickest, layer 126 next thickest, layer 127, next
thickest, layer 120 next
thickest and layer 129 is the least thick of the layers creating a compound
exponentially-shaped
response of an appropriate order to cushion the driver from the intrusive
impact.
An alternate embodiment of the mufti-phase energy absorbing a.nd impact
attenuating module 10 of
the present invention used in the aspect of a head rest 109 and cockpit
surround 120 of the same
configurations as FIG. 22A and FIG. 22B as shown in FIG. 22C includes thin,
pliable facing sheets
CA 02422415 2003-03-07
53
161 positioned at the boundaries of layers within the mufti-phase energy
absorbing and impact
attenuating module 10 to serve to further distribute and disperse impact
energy.
Generally, a decelerative impact will cause greater deceleration to the head
and body of the driver
than an external or intrusive impact and thus a preferred embodiment may be
that of the
decelerative impact configuration as depicted in FIG. 228.
Crash and Sports Helmets.
Referring now to FIG. 23 and FIG. 24, FIG. 23 depicts a crash helmet 80 of
prior art. An impact
with the crash helmet will firstly impact the outer shell 81 causing it to
deform or bend and deform
the underlying foam liner 82. The inner foam liner 82 provides an energy
absorbing and cushioning
barrier for the head. The comfort liner 83 serves to provide a comfortable fit
for the helmet but also
provides some cushioning of shock to the head as well. Helmets also generally
comprise a lower
liner 86, visor mount 85, edge beading 84 and a chinstrap assembly 87.
FIG. 24 illustrates an exemplary mufti-phase energy absorbing and impact
attenuating module 1
comprising the outer shell 91 and inner liner layers 93, 94, 95 and comfort
foam 92 in the aspect of
a crash helmet 98. In an exemplary embodiment, the outer shell 91, inner
layers 93, 94, and 95 are
concentric and annular. The outer shell comprises an injection ~~r pressure
molded shell made of
thermoset or thercmplastic material that may be glass fibre reinforced. The
outer shell 91 has
compressive strength, shear strength and tensile strength. The inner liner
comprises layers 93, 94,
95 of differing density or material generally manufactured of polystyrene,
polyurethane or other
energy absorbing foam fused, bonded or otherwise fixed adjacent to on.e
another in a concentric
annular arrangement. The outer layer of the inner liner is fused, bonded or
otherwise fixed adjacent
to the outer shell honeycomb panel 91 in a concentric annular arrangement, as
is the inner layer of
the inner liner with the comfort foam layer 92. Comfort foam layer 92 may be
continuous or
segmented.
In FIG. 24A, an embodiment of a crash helmet 98 zs depicted that, for example,
protects the wearer
from an external impact striking the crash helmet 98, for example, a rock or
errant part impacting
the helmet. The layers of energy absorbing materials are positioned such that
the comfort padding
layer 92 with the least compressive and/or crush strength is closest to the
head 97 of the wearer, the
layer 93 of next greatest compressive and/or crush strength is adjacent to the
inner surface of the
CA 02422415 2003-03-07
54
outer shell 91, the layer 94 of next greatest compressive and/or crush
strength is positioned adjacent
comfort padding layer 92 towards the outer shell 91, the layer 95 of greatest
compressive and/or
crush strength is positioned between layer 93 and 94 of the module. In the
exemplary embodiment,
layer 95 is of greatest density, layer 94 next densest, layer 93 next dense,
and layer 92 least dense of
the layers. On an external impact striking the helmet, impact energy displaces
the shell 91 towards
the head 97 of the wearer of the helmet, compressing the mufti-phase energy
absorbing and impact
attenuating module 10 against the head 97 as it does so. Impact energy and
forces load the multi-
phase energy absorbing and impact attenuating module 10 such that the layer
least resistive to the
impact energy and forces will compress firstly. Thus, although the stress wave
of impact energy will
propagate through, load and partially compress interceding layers 93, 95, and
94, layer 92
maximally distal to the impact will preferentially partially or fully crush
against the head 97. Layer
93 next least resistive to the impact energy and force located maximally
distal from layer 92 will
partially or fully crush next preferentially causing reflection and
propagation of the stress wave of
impact energy to travel a maximum amount and load and partially compress
interceding layers 94
and 95. Subsequently, the stress wave of impact energy will reflect and
propagate to the next least
resistive layer 94 positioned maximally distal from layer 93 so as to fully or
partially crush it and
load and partially crush interceding layer 95 which will partially or fully
crush lastly. In the
exemplary embodiment, layer 92 is thickest, layer 93 next thickest, layer 94
next thickest, and layer
95 is the least thick of the layers creating a compound exponentially-shaped
response of an
appropriate order to cushion the head 97 from the external impact.
In FIG. 24B, an alternate embodiment of a crash helmet 98 is depicted that,
for example, protects
the wearer from a decelerative impact, e.g., the helmet 98 striking the
roadway on a fall from a
motorcycle. The layers of energy absorbing materials are positioned such that
the layer 92 with the
least compressive and/or crush strength is adjacent to the inner surface of
the outer shell 91, the
comfort padding layer 93 of next greatest compressive and/or ez°ush
strength is closest to the head
97 of the wearer, the layer 94 of next greatest compressive and/or crush
strength is positioned
adjacent layer 92 towards the head 97 of the wearer, the layer 95 of greatest
compressive and/or
crush strength is positioned between layer 93 and 94 of the module. In the
exemplary embodiment,
layer 95 is of greatest density, layer 94 next densest, layer 93 next dense,
and layer 92 least dense of
the layers. On an impact of the crash helmet 98 staking an object, for example
a roadway, the
wearer's head 97 is forced against the mufti-phase energy absorbing and impact
attenuating module
comprising layers 92, 93, 94 and 95. Impact energy and forces load the mufti-
phase energy
CA 02422415 2003-03-07
absorbing and impact attenuating module 10 such that the layer least resistive
to the impact energy
and forces will compress firstly. Thus, although the stress wave of impact
energy will propagate
through, load and partially compress interceding layers 93, 95, and 94, layer
92 maximally distal to
the impact of the head 97 against the helmet liner will preferentially
partially or fully crush against
the shell. Comfort padding layer 93 next least resistive to the impact energy
and force located
maximally distal from layer 92 will partially or fully crush next
preferentially causing reflection and
propagation of the stress wave of impact energy to travel a maximum amount and
load and partially
compress interceding layers 94 and 95. Subsequently, the stress wave of impact
energy will reflect
and propagate to the next least resistive layer 94 positioned maximally distal
from layer 93 so as to
fully or partially crush it and load and partially crush interceding layer 95
which will partially or
fully crush lastly. In the exemplary embodiment, layer 92 is thickest, layer
93 next thickest, layer 94
next thickest, and layer 95 is the least thick of the layers creating a
compound exponentially shaped
response of an appropriate order to cushion the head from the external impact.
An alternate embodiment of the crash helmet 98 of the same configurations as
FIG. 24A and FIG.
24B includes thin, pliable facing sheets 161 positioned at the boundaries of
layers within the multi-
phase energy absorbing and impact attenuating module 10 as shown in FIG. 24C
in the aspect of a
crash helmet liner to serve to further distribute and disperse impact energy.
Generally, a decelerative impact will cause greater deceleration to the head
and body of the driver
than an external or intrusive impact and thus a preferred embodiment may be
that of the
decelerative impact configuration as depicted in FIG. 248.
FIG. 25 and FIG. 26 depict a sport helmet 150 of prior art. The outer shell
151 is generally made of
hard thermoplastic or thermoset material. The inner liner typically comprises
a single layer liner 152
of expanded polypropylene (EPP) with comfort or sizing padding 159.
Referring now to FIG. 27, a sport helmet with the mufti-phase energy absorbing
and impact
attenuating module 10 of the present invention in the aspect of a helmet liner
is shown. The outer
shell 151 is preferably made of a thermoset or thermoplastic material and
consistent with the outer
shell of sport helmets of prior art.
CA 02422415 2003-03-07
56
In FIG. 27A, an embodiment of a sport helmet 158 is depicted that, for
example, protects the wearer
from an external impact striking the helmet, for example, a hockey puck or
other player impacting
the helmet. The layers of energy absorbing materials are positioned such that
the comfort padding
layer 152 with the least compressive and/or crush strength is closest to the
head of the wearer, the
layer 153 of next greatest compressive and/or crush. strength is adjacent to
the inner surface of the
outer shell 151, the layer 154 of next greatest compressive and/or crush
strength is positioned
adjacent comfort padding layer 152 towards the outer shell 151, the layer 155
of greatest
compressive and/or crush strength is positioned between layers 153 and 154 of
the module. In the
exemplary embodiment, layer 155 is of greatest density, layer 154 next
densest, layer 153 next
dense, and layer 152 least dense of the layers. On an external irr~pact
striking the sport helmet 158,
impact energy displaces the shell 151 towards the head 159 of the wearer of
the helmet,
compressing the mufti-phase energy absorbing and impact attenuating module 10
against the head
159 as it does so. Impact energy and forces load the mufti-phase; energy
absorbing and impact
attenuating module 10 such that the layer least resistive to the impact energy
and forces will
compress firstly. Thus, although the stress wave of impact energy will
propagate through, load and
partially compress interceding layers 153, 155, and 154, layer 152 maximally
distal to the impact
will preferentially partially or fully crush against the head 159. Layer 153
next least resistive to the
impact energy and force located maximally distal from layer 152 will partially
or fully crush next
preferentially causing reflection and propagation of the stress wave of impact
energy to travel a
maximum amount and load and partially compress interceding layers 154 and 155.
Subsequently,
the stress wave of impact energy will reflect an propagate to the next least
resistive layer 154
positioned maximally distal from layer 153 so as to fully or parl:ially crush
it and load and partially
crush interceding layer 155 which will partially or fully crush lastly. In the
exemplary embodiment,
layer 152 is thickest, layer 153 next thickest, layer 154 next thickest, and
layer 155 is the least thick
of the layers creating a compound exponentially-shaped response of an
appropriate order to cushion
the head from the external impact.
In FIG. 27B, an alternate embodiment of a sport helmet 158 is depicted that,
for example, protects
the wearer from a decelerative impact of the helmet, e.g., the sport helmet
158 striking the roadway
on a fall from a bicycle, skateboard or roller blades. The layers of energy
absorbing materials are
positioned such that the layer 1 S2 with the least compressive an.d/or crush
strength is adjacent to the
inner surface of the outer shell 151, the comfort padding layer 153 of next
greatest compressive
and/or crush strength is closest to the head 159 of the wearer, the Payer 154
of next greatest
CA 02422415 2003-03-07
57
compressive and/or crush strength is positioned adjacent layer 152 towards the
head 159 of the
wearer, the layer 155 of greatest compressive and/or crush strength is
positioned between layer 153
and 154 of the module. In the exemplary embodiment, layer 155 is of greatest
density, layer 154
next densest, layer 153 next dense, and layer 152 least dense of the layers.
On an impact of the sport
helmet 158 striking an object, for example a roadway, the wearer's head 159 is
forced against the
mufti-phase energy absorbing and impact attenuating module 1C~ comprising
layers 152, 153, 154
and 155. Impact energy and forces load the mufti-phase energy absorbing and
impact attenuating
module 10 such that the layer least resistive to the impact energy and forces
will compress firstly.
Thus, although the stress wave of impact energy will propagate through, load
and partially
compress interceding layers 153, 155, and 154, layer 152 maximally distal to
the impact of the head
against the liner will preferentially partially or fully crush against the
shell 151. Comfort padding
layer 153 next least resistive to the impact energy and force located
maximally distal from layer 152
will partially or fully crush next preferentially causing reflection and
propagation of the stress wave
of impact energy to travel a maximum amount and load and partially compress
interceding layers
154 and 155. Subsequently, the stress wave of impact energy will reflect and
propagate to the next
least resistive layer 154 positioned maximally distal from layer I 53 so as to
fully or partially crush
it and load and partially crush interceding layer 155 which will partially or
fully crush lastly. In the
exemplary embodiment, layer 152 is thickest, layer 153 next thickest, layer
154 next thickest, and
layer 155 is the least thick of the layers creating a compound eXponentially-
shaped response of an
appropriate order to cushion the head from the extet-nal impact.
An alternate embodiment of the sport helmet 158 of the same configuration as
FIG. 27A and FIG.
27B includes thin, pliable facing sheets positioned at the boundaries of
:layers within the mufti-phase
energy absorbing and impact attenuating module 10 in the aspect of a sport
helmet liner to serve to
further distribute and disperse impact energy. FIG. 28 depicts the sport
helmet 158 of the same
configuration as FIG. 27B, but with thin, pliable facing sheets 1 < 1
positioned at the boundaries of
layers 153 and 155, layers 155 and 154, and layers 154 and 152 to serve to
further distribute and
disperse impact energy.
Generally, a decelerative impact will cause greater deceleration to the head
and body of the driver
than an external or intrusive impact and thus a preferred embodiment may be
that of the
decelerative impact configuration as depicted in FIG. 27B.
CA 02422415 2003-03-07
5g
FIG. 29 shows an exemplary mufti-phase compound exponentially-shaped stress
versus strain
response achieved with the mufti-phase energy absorbing and impact attenuating
module 10 in the
aspect of a crash helmet liner or sport helmet liner as depicted in FIG. 24
and FIG. 27 respectively
in which changes in impact dynamics and decelerative forces are gradual and
integrated rather than
abrupt, and a gradually increasing cushioning of the impact occurs.
FIG. 30 shows an exemplary mufti-phase compound exponentially-shaped stress
versus strain
response achieved with the mufti-phase energy absorbing and impact attenuating
module 10 of a
different order in which changes in impact dynamics and decelerative forces
are gradual and
integrated rather than abrupt, and a gradually increasing cushioning of the
impact occurs but the
impacting body is decelerated more slowly for a longer period a.nd deflection
of the mufti-phase
energy absorbing and impact attenuating module 10 and then decelerated more
quickly for the
remainder of the deflection of the mufti-phase energy absorbing and impact
attenuating module 10
as compared to FIG. 29 in a manner that may be advantageous for relatively low
impact energies
yet have the capacity to accommodate higher impact energies eivfectively.
FIG. 31 shows an exemplary mufti-phase compound exponentially-shaped stress
versus strain
response achieved with the mufti-phase energy absorbing and impact attenuating
module 10 of a
different order in which changes in impact dynamics and decel~rative forces
are gradual and
integrated rather than abrupt, and a gradually increasing cushioning of the
impact occurs but the
impacting body is decelerated more quickly initially and for less deflection
of the mufti-phase
energy absorbing and impact attenuating module 10 and then decelerated more
quickly for the
remainder of the deflection of the mufti-phase energy absorbing and impact
attenuating module 10
as compared to FIG. 30 in a manner that may be advantageous i=or relatively
high impact energies
yet have the capacity to accommodate even higher impact energies effectively.
By utilizing varying mufti-phase compound exponentially-shaped stress versus
strain response
achieved with the mufti-phase energy absorbing and impact attenuating module
10, the same helmet
design can be used with liners of common total thickness T, but: with varying
abilities to absorb
impacts, e.g., low impact energy for children's or recreational helmets, yet
higher impact absorbing
capacity for elite or professional athlete's helmets.
CA 02422415 2003-03-07
59
Conceivably, those persons knowledgeable in this field of endeavor will, upon
studying this
disclosure, consider various modifications and/or improvements to the
inventive concept presented,
but still within this concept. Though primarily designed for the embodiments
and aspects as
mentioned herein, this in no way limits the use of the present invention. In
fact, similar mufti-phase,
energy absorbing and impact attenuating modules may be useful in a wide
variety of applications in
which energy absorption and impact attenuation of an incident body to minimize
injury and damage
are desired. Therefore, the invention herein is not to be limited t~o the
preferred or other
embodiments and aspects set forth as exemplary of the invention, but only by
the scope of the
claims and the equivalents thereto.
CA 02422415 2003-03-07
REFERENCES:
Yasui, Yoshiaki. Dynamic axial crushing of mufti-layer honeycomb panels and
impact
tensile behavior of the component members. International Journal of Impact
Engineering. Vol. 24;
No. 6. 2000. pp. 659-671.
