Note: Descriptions are shown in the official language in which they were submitted.
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MACRO-PATTERNED MATERIALS AND STRUCTURES
FOR VEHICLE ARRESTING SYSTEMS
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application
Serial
No. 61/947,194, filed March 3, 2014, titled "The use of Macro-patterned
materials
structures for vehicle arresting systems," the entire contents of which are
hereby
incorporated by reference.
FIELD OF THE DISCLOSURE
[0002] Embodiments of the present disclosure relate generally to macro-
patterned
materials and methods of their use in connection with vehicle arresting
systems.
Certain embodiments provide 3-D folded materials, honeycombs, lattice
structures,
and other periodic cellular material structures, that can be used for
arresting vehicles.
The materials can be engineered to have properties that allow them to reliably
crush in
a predictable manner under pressure from a vehicle. The materials can be
formed into
various shapes and combined in various ways in order to provide the desired
properties.
BACKGROUND
[0003]
Aircraft can and do overrun the ends of runways, raising the possibility of
injury to passengers and destruction of or severe damage to the aircraft. Such
overruns have occurred during aborted take-offs or while landing, with the
aircraft
traveling at speeds up to 80 knots. In order to minimize the hazards of
overruns, the
Federal Aviation Administration (FAA) generally requires a safety area of one
thousand feet in length beyond the end of the runway. Although this safety
area is
now an FAA standard, many runways across the country were constructed prior to
adoption of this standard. These runways may be situated such that water,
roadways,
or other obstacles prevent economical compliance with the one thousand foot
overrun
requirement.
[0004] In
order to alleviate the severe consequences of overrun situations, several
materials, including existing soil surfaces beyond the runway, have been
assessed for
their ability to decelerate aircraft. However, soil surfaces are not the best
solution for
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arresting moving vehicles (i.e. aircraft), primarily because their properties
are
unpredictable.
[0005]
Another system that has been explored is providing a vehicle arresting
system or other compressible system that includes material or a barrier placed
at the
end of a runway that will predictably and reliably crush (or otherwise deform)
under
the pressure of aircraft wheels traveling off the end of the runway. The
resistance
provided by the compressible, low-strength material decelerates the aircraft
and
brings it to a stop within the confines of the overrun area. Specific examples
of
vehicle arresting systems are called Engineered Materials Arresting Systems
(EMAS),
and are now part of the U.S. airport design standards described in FAA
Advisory
Circular 150/5220-22B "Engineered Materials Arresting Systems (EMAS) for
Aircraft Overruns" dated September 30, 2005. EMAS and Runway Safety Area
planning are guided by FAA Orders 5200.8 and 5200.9.
[0006] A
compressible (or deformable) vehicle arresting system may also be
placed on or in a roadway or pedestrian walkway (or elsewhere), for example,
for
purposes of decelerating vehicles or objects other than aircraft. They may be
used to
safely stop cars, trains, trucks, motorcycles, tractors, mopeds, bicycles,
boats, or any
other vehicles that may gain speed and careen out of control, and thus need to
be
safely stopped.
[0007] Some specific materials that have been considered for arresting
vehicles
(particularly in relation to arresting aircraft), include phenolic foams,
cellular cement,
foamed glass, and cellular chemically bonded phosphate ceramic (CBPC). These
materials can be formed as a shallow bed in an arrestor zone at the end of the
runway.
When a vehicle enters the arrestor zone, its wheels will siffl( into the
material, which
is designed to create an increase in drag load.
[0008]
However, some of the materials that have been explored to date can be
improved upon. For example, phenolic foam may be disadvantageous in that is
has a
"rebound" characteristic, resulting in return of some energy following
compression.
Cellular concrete has density and compressive strength properties that may
vary with
time and that could be difficult to maintain in production due to the innate
properties
of its variable raw materials and subsequent hydration process. Foamed glass
can be
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difficult to control in uniformity. It is thus desirable to develop improved
materials
for vehicle arresting beds.
BRIEF SUMMARY
[0009]
Embodiments of the invention described herein thus provide systems and
methods for designing vehicle arresting systems using macro-patterned
materials or
structures that can be engineered to have properties that allow them to
reliably crush
in a predictable manner under pressure from a vehicle. The materials can be
formed
into various shapes and combined in various ways in order to provide the
desired
properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG.
1 shows a top perspective view of one embodiment of a macro-
patterned material, specifically a 3-D folded structure in a chevron pattern
on an
aluminum alloy sheet.
[0011] FIG.
2 shows a top perspective view of one embodiment of a macro-
patterned material that is a 3-D folded structure in a chevron pattern on a
different
aluminum alloy material.
[0012] FIG.
3 shows a top perspective view of another embodiment of a macro-
patterned material.
[0013] FIG.
4 shows a side perspective view of one embodiment of a machine that
may be used to form folds or patterns on a material sheet.
[0014] FIG.
5A shows blocks formed from a plurality of macro-patterned material
structures.
[0015] FIG.
5B shows a panel made from a plurality of blocks formed from a
plurality of macro-patterned material structures.
[0016] .. FIG. 6 shows a block formed from a plurality of macro-patterned
material
structures.
[0017]
FIGS. 7A-7H show alternate structure shapes that are within the scope of
this disclosure.
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[0018] FIG. 8 shows one embodiment of a honeycomb pattern.
[0019] FIG. 9 shows a schematic of a honeycomb pattern with outer panels
on
both sides of the honeycomb core.
[0020] FIG. 10 shows one embodiment of a honeycomb sandwich panel.
[0021] FIG. 11 shows one embodiment of a honeycomb sandwich panel with
scored outer panels.
[0022] FIGS. 12A and 12B show a schematic of an aircraft wheel
contacting the
honeycomb embodiments, having varying orientation of cell axes.
[0023] FIG. 13 shows a schematic of stacked honeycomb blocks or panels.
[0024] FIG. 14 shows a schematic of adhesive layers that may be positioned
between various structures that form a block.
[0025] FIGS. 15A and 15B show fire testing results for a honeycomb core
and a
honeycomb panel.
[0026] FIG. 16 shows various types of lattice structures that are within
the scope
of this disclosure.
DETAILED DESCRIPTION
[0027] Embodiments of the present invention provide materials that are
designed
in a way that renders them useful for arresting vehicles. In one aspect, the
materials
are provided as macro-patterned materials. As used herein, the phrase "macro-
patterned materials" or "macro-patterned structures" is used to mean
structures that
are made of repetitive units in three dimensional ("3-D") spaces. They may
include
minimum feature sizes for each unit that are equal to or larger than about 1
millimeter.
The materials or structures may include 3-D folded materials, lattice
structures,
honeycomb structures, and any other type of periodic cellular structures.
[0028] As used herein, "periodic cellular material structures" refers to
materials
that have similar structures to those of periodic cellular metals (for
example, those
described in Haydn N. G. Wadley, "Multifunctional periodic cellular metals",
Phil.
Trans. R. Soc. A (2006) 364, 31-68), but they are not limited to metallic
materials.
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Such periodic cellular material structures can be made of any viable materials
including metallic materials, ceramics, plastics, papers, and composites
thereof, or
combinations thereof Furthermore, non-periodic cellular materials having the
feature
size defined above also fall into the scope of macro-patterned materials and
structures.
[0029] In one example, the materials are folded three-dimensional
structures.
The structures may be formed by being folded or pressed or tessellated or
otherwise
engineered. These materials can be formed in any number of optional shapes and
configurations and layers. In other embodiments, the materials are formed as
lattice
structures, a geometrical arrangement of objects or points, rods, sticks,
inflatable
structures, or any other structure, such as interlaced structures and
patterns,
honeycombs, and folded honeycombs.
[0030] The
macro-patterned materials or structures described herein can be made
of metals and alloys thereof, foils, plastics, paper, related materials, or
combinations
thereof More options are provided in the below description. Such materials or
structures may be manufactured so that they exhibit energy absorbing
capacities when
tailored for use as vehicle arresting systems. By generating a dragging force
from a
vehicle wheel or other vehicle structure upon interaction with the materials,
the
kinetic energy of the moving vehicle can be absorbed so that the vehicle can
be
decelerated or stopped with minimal damage to the vehicle and with reduced to
no
injury to the vehicle occupants. By changing the geometric configurations and
material properties of various materials or structures, moving vehicles of
different
weights can be safely stopped within predetermined ranges. (The vehicles that
may
be stopped include any land-based, wheeled moving systems, such as cars,
trucks,
bicycles, aircraft after landing or before taking-off, and so forth.)
[0031] Vehicle arresting systems refer to systems for installation at the
ends of
aircraft runways or other vehicle safety areas. They provide an external
source of
energy absorption. They are separate from the vehicle structure itself Vehicle
arresting systems are generally effective to safely decelerate vehicles
entering the
systems. They may be provided as a bed, a raised barrier, an indented area on
a
runway that is filled with materials, or any other appropriate system. The
arresting
systems disclosed are generally assembled of the macro-patterned materials and
structures described herein.
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[0032] The
materials and structures may be engineered so that failure mode will
meet desired performance requirements. For example, the pieces of material
deform
or break upon application of a force in a controlled way, such that they do
not pose a
severe hazard to the vehicle or its occupants. The materials are generally
engineered
to have desired properties for a wheel of an overrun aircraft to penetrate the
material
so that aircraft is stopped. In some examples, the materials may be considered
"brittle." Additionally, federal regulations may dictate that the size of the
resulting
pieces from the broken or crushed materials or structures be such that they
are small
enough to not cause safety issues on a runway. Another example is that
materials and
structures may be engineered or treated to meet non-flammability requirements.
[0033] In
one specific example, folding of flat sheets of materials into intricate 3-
D structures has been found to provide a strength to density ratio that can be
useful in
arresting vehicles. As background, folded material structures and honeycombs
have
been developed and used for other applications, such as for acoustic
applications for
noise reduction, for protection in air drop of relief and aid supplies to
reduce impact
force (e.g., as an air drop cushion), as elastic shock absorbers, as building
skeletons,
or in packaging perfumes and other fragile items. The goal for each of these
uses,
however, is for the material to withstand an impact and to not shatter or
break. By
contrast, the desired intent of the materials described in this application is
that they
are designed to reliably crush in a controlled manner under impact from a
vehicle so
as to safety stop the vehicle, while minimizing injury to the vehicle
occupants and
damage to the vehicle.
[0034] One
folding theory that may be used to provide the structures described
herein is a sheet of material that is folded into a 3-D pattern. This can
create a core
structure 10, examples of which are shown in Figures 1-3. Once formed, the
core
structure 10 may be combined with other core structures 10 in various
geometries and
arrangements and patterns in order to provide the desired compressive
strength, as
outlined further below.
[0035]
Scientists have developed mathematical theories that generate repetitive
geometric patterns that can be folded from flat sheets. The theories generate
an
extensive variety of patterns, all of which are considered within the scope of
this
disclosure. (Many of these theories were developed and pioneered by D.H. Kling
of
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Rutgers University, and are outlined in related literature published by Dr.
Kling and
his team. For example, processes for generating different patterns for various
structures are described in the paper titled "Applications of Folding Flat
Sheets of
Materials Into 3-D Intricate Engineering Designs" by E.A. Elsayed and B. B.
Basily
of Rutgers University, the entire contents of which are incorporated by
reference.)
[0036] Any
type of folding technology may be used to form the core structures 10
described. Some examples include but are not limited to continuous folding
using
rollers, discrete folding using die, and vacuum folding. One example of a
potential
folding process is shown in Figure 4. In this example, a sheet of material 12
may be
pressed by rollers 14 in order to provide a raised pattern 16 or a creased
pattern on the
sheet. The sheet with a raised pattern may then be sent through another set of
rollers
¨ cross folding rollers ¨ that are engraved with a pattern to create
additional folds and
patterns. More specifically, the sheet 12 may be pre-folded by being sent
through a
set of sequential circumferentially grooved rollers. The pre-folded sheet may
then be
sent through a set of cross folding rollers engraved with a specific pattern.
This
continuous folded sheet may they be cut into the desired dimensions. In some
examples, the specific pattern may be a chevron-like or triangular pattern.
The raised
pattern 16 that is formed may be a chevron pattern, such as that shown in
Figures 1-3.
The chevron pattern may generally provide a series of nested V-shape features.
In
other examples, the raised pattern may be a mating surface ("MS") pattern, as
shown
in Figure 7A. The MS patter generally provides offset triangular faces. In
other
examples, the specific pattern may be a box pattern or a castellated pattern
(Figures
7B and 7C), a curved or sin wave-like pattern, a chevron with flat surfaces
(rather
than points) (Figure 7D), reflective (or star-like) surfaces (Figure 7E),
bearing
surfaces reflector (Figure 7F), or any other pattern. Additional non-limiting
examples
are shown in Figures 7G and 7H. Any other patterns are possible and are
considered
within the scope of this disclosure. Other examples of potential raised
surfaces
include but are not limited to a chevron pattern. Other patterns may include a
honeycomb pattern and any other pattern that provides the desired energy
absorbing
properties.
[0037] In
another example, a die may be created by forming and arranging desired
tessellation units. Once the die is formed, a sheet of material having a
specific
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dimension may be pressed against the die to form the desired folded shape. The
resulting structure has the desired folded pattern.
[0038] In
another example, a sheet of material may be subjected to heat and
stretched. This method is particularly useful for polymeric, plastic, or
composite
material sheets. A vacuum may then be applied to force the malleable sheet
against a
die engraved with the desired folded pattern. Combinations of these techniques
may
also be used. Other methods of 3-D folding or forming 3-D folded structures
are
possible and considered within the scope of this disclosure.
[0039] The
criteria to consider when determining what raised pattern to use
include but are not limited to the desired impact strength, energy absorption,
crush
strength, compressive gradient, and any other factors. The material may be
modified
as desired as well. For example, materials may be selected having certain
density and
corrosion resistance, and may be formed with specific geometries and heights.
[0040] The
properties of the final materials and the structure selected may be
tailored through engineering. Changes may be made to the raw sheet materials,
their
thickness, folded pattern, and pattern geometry. Flexibility in design for
selecting
property and performance characteristics can allow better and more cost-
effective use
of materials for various applications.
[0041] For
example, the sheet of material may be a sheet metal. The sheet of
material may be a foil, a metal foil such as a foil of aluminum or copper or
their
alloys. The sheet of material may be paper, such as paperboard, fiberboard,
corrugated material, fire resistant paper, or fiberglass reinforced
composites. The
material may be a plastic, such as thermoplastic materials, other polymers
composite
material, thermoplastic materials, polymers (including but not limited to
polyethylene,
polypropylene, polyvinyl chloride, polystyrene, acrylonitrile butadiene
styrene), or a
composite material, such as reinforced plastic or combinations thereof The
material
may be a reinforced composite, a carbon fiber, a reinforced composite
material,
ceramic, cementitious materials, or combinations thereof
[0042] That
material may be any combination of the above materials. It is also
envisioned that other materials are possible and considered within the scope
of this
disclosure. Inflatable materials may also be explored and are considered
within the
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scope of this disclosure. The material may be any appropriate material that
can be
deformed upon application of appropriate pressure, heat, or other means. The
raw
material properties may be selected to provide the desired crush strength.
Parameters
such as yield strength, ultimate strength, heat treating history, and chemical
stability
may be considered. In a specific example, 1100 series aluminum alloy has been
tested and has shown good performance in various vehicle arresting
applications.
[0043] One
concept that the present inventors have identified is that for the
structure (or a plurality of structures in combination) to reliably crush, it
may be
desirable for the pattern selected to be less anisotropic, such that it is
generally
uniform in most, if not all, directions. The core structure 10 may be formed
so that its
folds and other dimensions are generally similar across various cross-sections
of the
structure 10.
[0044] The
structures are generally stacked or formed into larger structures that
form the vehicle arresting system. In one example, the macro-patterned
lattice,
honeycomb or 3-D structured material is formed into a body that has a defined
structure formed by the individual pieces. The macro pieces (which may be any
shape, such as spheres, folded sheets, rods, flat panels, honeycomb panels,
and so
forth) may be placed in a set volume. This may be a box, a cube, stacked to
form a
certain body, assembled in layers, positioned in a bed, or any other option.
They may
have a defined position, such that there is a repetitive pattern. This
repetitive pattern
may be formed by stacked structures that may be oriented in different ways. In
another example, the individual pieces or structures can be loose or attached
by any
means, such as being glued, welded, interlocked, or any other appropriate
option. In
short, the assembling is generally not random. The structures are not combined
in
any way, but are generally architected to create repeating patterns. This can
assist
with providing a system that provides reliable crushing from many directions.
[0045] The
present inventors have also determined that certain thicknesses of the
material also lend to its use as a vehicle arresting system. In one example,
the
thicknesses of the material prior to folding may range from about 0.003 inch
to about
0.016 inch. In another example, the thickness of the material prior to folding
may be
from about 0.005 to about 0.015. In another example, the thickness of the
material
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prior to folding may be less than about 0.5 millimeter, and particularly less
than about
0.3 millimeter.
[0046] In one example, the height of the raised patterns 16 formed on
the folded
material may be from about 0.3 inch to about 2 inches. Specific ranges may be
from
about 0.4 inch to about one or 1 'A inches. It is generally advantageous for
this height
to be uniform or otherwise generally consistent across the entire structure
10. This
can allow the structure to reliably crush, no matter what part of it receives
the impact.
Providing an evenly distributed pattern can assist with the desired
reliability of
crushing upon impact.
[0047] As outlined above, the resulting structure 10 that is formed may
also be
stacked or layered with other structures to form a block 18 of core
structures.
Examples of a plurality of blocks or units of core structures are shown in
Figures 5
and 6. The block 18 of core structures may be formed of structures 10 having
the
same materials and the same or similar geometry. In another example, the block
18 of
core structures may be formed of structures having different materials and the
same or
similar geometry. In another example, the block 18 of core structures may be
formed
of structures having the same materials and different geometries. Any
combination of
these features may be used. As mentioned, one specific example provides
structures
10 that have similar geometries, such that the block 18 of core structures is
less
anisotropic.
[0048] The structures 10 may be layered in any number of orientations.
For
example, in the example shown in Figure 5A, the structures may be stacked on
top of
one another longitudinally. In another embodiment, they may be aligned in a
side-by-
side vertical-like arrangement, as shown in Figure 6. An insert layer 20 may
be
inserted between each layer of stacked structures, as shown in Figure 5A.
Alternatively, the structures may be stacked directly against one another. In
a further
embodiment, the structures 10 may be twisted or rolled into a rounded unit or
block.
Any other configuration option is possible and is considered within the scope
of this
disclosure. The structures may have different top and/or bottom layers,
different
intermediate layers, or the layers may all be similar.
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[0049] In
one example, the structures 10 forming the layers may be glued to one
another. In another example, the structures 10 forming the layers may be
welded to
one another. In another example, the structures 10 forming the layers may be
cemented (using e.g., crushable nonflammable materials) to one another.
Intermediate layers 20 may be glued and/or welded in place. It is possible to
incorporate filler materials (not shown) in any areas of gaps in the folded
structures
10. The filler materials may include but are not limited to stable, crushable,
and non-
flammable materials. Examples include a very lightweight ceramic foam. Further
examples include a loose powder, a weak ceramic cement, a jelly, a foam,
various
types of sand, combinations thereof, and any other appropriate options. The
filler
may fill cavities of the macro-patterned structure, which may improve its
performance
and/or change the response behavior of the resulting vehicle arresting system.
[0050] In
one specific embodiment, a block 18 may be made by orienting a
plurality of the folded layers/structure 10 alternately in two different
directions.
These 2 directions may be perpendicular to one another. An intermediate layer,
un-
folded flat sheet 20 may be added between structures 10. This can help build
(with
adhesive or other means of bonding) block units 18. In one specific aspect,
the block
units 18 are about five cubic inches each. Other dimensions are possible and
considered within the scope of this disclosure. For example, the blocks may
range
from 1 cubic inch to about 12 cubic inches in size.
[0051]
These block units 18 can have less anisotropic compressive yield strength.
For example, the strength difference in different directions may be less than
30%.
Less anisotropy in compressive yield strength can be desirable in vehicle
arresting
performance. (It is anticipated that the vehicle may approach and contact the
block 18
from one of any number of different directions). The block units 18 may then
be
arranged in a level and bonded with adhesive or other means of bonding with
unfolded face sheet(s) 20. These intermediate layer sheets 20 may have a
thickness of
about 0.003-0.016 inches at top and/or bottom. In one aspect, the thickness of
the
intermediate layer 20 can be similar to or different from the thickness of the
initial
sheet used to make the folded structure 10.
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[0052]
Different levels of bonded units or blocks 18 can be bonded further,
adding one level above another to form larger blocks. These blocks may be
rectangular in shape, square, or any other appropriate dimension or shape.
[0053]
Figure 5A shows a plurality of units 18 that were built with folded
structures 10, unfolded intermediate layers 20, a top layer 22 (unfolded), a
bottom
layer 24 (unfolded), and adhesives. In this example, each unit 18 is generally
cube
shaped and has one or more flat inter-layers or intermediate layers 20 in
between any
two adjacent folded structure 10 layers. The orientations of the folded
structure 10
layers were alternate as described previously to achieve the same strength in
two
mutually perpendicular directions. Because materials may have different
strengths in
different directions, it may be desirable to reduce the strength difference by
alternating layer orientations. The height of the folded structure layer is
also
determined from testing and achieved by selecting and using appropriate
folding tools
to minimize the difference in strength between lateral and vertical
directions.
Adjusting the parameters, such as thickness of the raw material sheet, the
material of
the sheet, height of the folds, interlayer thickness, and other parameters to
obtain the
desired material strength and reduced anisotropy of strength in different
directions can
be achieved. For example a range of folded layers may be from 0.3 to about 1.5
inches.
[0054] Figure 5B shows a larger block 26 made of thirty six cube units 18,
each of
which is a cube 18 of 5 inch x 5 inch x 5 inch. For this example, adhesives
are used
to bond the cubes 18 together. In addition, face sheets 28 were bonded to the
top and
bottom of two levels of cube units 18. In between the two levels of cubes 18,
there is
also a large flat sheet 30 used to bond the two levels of cube units together.
Apart
from the large face sheets 28 and the large flat sheet 30 in between any two
levels of
the cubes, no additional bonding was used between adjacent cube units 18. It
should
be understood, however, that bonding adhesives or other securing materials may
be
used if desired. Higher blocks 26 may be made by adding more levels and a flat
sheet
in between any adjacent levels. It should be understood that the heights and
other
30 aspects
of the units 18 used in the block 26 need not be the same. For example,
blocks of varying materials, varying geometries, and varying designs may be
used.
However, one benefit of using blocks 18 of similar materials, geometries, and
designs
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may be that the larger block 26 that is formed is less anisotropic and may
crush
reliably and predictably.
[0055]
Figure 6 shows an embodiment in which the structures 10 are positioned
vertically with respect to one another, so that there is a larger space
between each
intermediate layer than when they are positioned horizontally as shown in
Figures 5A
and 5B.
[0056] It
should also be understood that the thicknesses of the face sheets 28 and
flat sheets 30 may be varied to provide varying crush profiles. This can allow
the
units 18 or larger block 26 to be designed to meet various performance
requirements,
for example, in the case of the desired vertical strength change with height.
The
concept of using units 18 of certain sizes to build larger blocks 26 and
controlling the
bonding between units 18 in the blocks 26 can help ensure good failure mode
during
vehicle arrestment.
[0057] In
the examples shown, a chevron pattern was tested. Although this
pattern was found to provide test results that show good energy absorption
characteristics for the intended application in vehicle arresting systems, it
should be
understood that other patterns may be used and are considered within the scope
of this
disclosure.
[0058] In
other embodiments, the macro-patterned materials may be formed as
lattice structures, honeycombs, folded honeycombs, or other periodic cellular
structures. For example, a honeycomb structure 32 may be formed as a honeycomb-
shaped cell structure 34 being sandwiched between two outer panels 36. An
example
of a honeycomb cell structure 34 is illustrated in Figure 8. The cell sizes
may range
from about 1/4 inch up to about one inch. It is possible for the cell sizes to
be even
larger, depending upon the materials used. The cell types may be rectangular,
hexagonal, or any other appropriate shape. Honeycomb core structures typically
have
a load bearing capacity in one dimension and are extremely anisotropic in
terms of
mechanical properties. However, through engineering (such as, by adding face
panel
and adjusting the core height, or using folded honeycomb structures so that
the final
honeycomb structures can withstand load from different directions), the
material can
become less anisotropic.
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[0059] The
cell axes may be designed or oriented so that they have a crush
strength that is similar from different directions. In one example, the
material for the
honeycomb-shaped cell structure 34 may be sheet or foil of metal or alloys
such as
aluminum or other metal alloy. The material may be plastic. The material may
be
paper, such as aramid paper, cardboard, or other options. The material may be
ceramics, cementitious materials, composites, combinations thereof, or other
appropriate material that may have the desired crushability aspects.
[0060] A
schematic example of a honeycomb structure 32 with outer panels 36 is
illustrated in Figure 9. An actual example of a honeycomb structure 32 is
shown in
Figure 10. The outer panels 36 may be made of the same or different material
as the
cell structure 34. The outer panels 36 provide a "skin" to the honeycomb
structure 32
that provides a more rigid panel.
[0061] The
gauge of the material(s) and/or the thickness of the material(s) may be
optimized to provide the desired crushability of the resulting structure. For
example,
the gauge of the material may range from a thin aluminum foil thickness to a
rigid
sheet of metal. The thickness of the assembled honeycomb panels may range from
about 1/4 inch to about 40 inches in height H. In a specific embodiment, the
panels are
about 24 inches high. In another embodiment, assembled blocks of multiple
panels
may be up to about 40 inches high. It should be understood that the height can
be
varied to meet the needs, and heights higher than 40 inches are possible.
[0062] As
shown in Figure 11, the outer panels 36 may be scored or have one or
more cuts 38 made in the skin of the panel 36. This can help enhance the
energy
absorbing features of the structures 32, either alone or as a combined
structure 32.
The scores 38 may be generally parallel as shown, or they may be random or at
various directions. The scores or cuts have been shown to provide a desired
drag load
in testing.
[0063]
Figure 12 shows various options for the directions of the cell axes 40. In
Figure 12A, the cell axes 40 are angled at 22 . Figure 12B, the cell axes 40
are angled
at 45 . Tests have been conducted on 90 (vertical cell axis), 45 , and 22 .
Under
certain tests conditions, it was found that 45 worked well. However other
angles
may be used depending upon the expected engagement angle of the vehicle wheel.
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Scientific literature has established strength as a function of cell axis
angle. It has
been found that the strength of the honeycomb structure 32 may be a function
of the
cell axis 40. In these examples, the honeycomb structure 32 may be secured to
a base
panel B via any appropriate means. In one example, they may be secured to the
base
panel B via as adhesive. One or more honeycomb structures 32 may be placed end
to
end.
[0064] In
another example, Figure 13 shows that a plurality of honey comb
structures 32 may be stacked to form a combined structure 42. In this example,
the
structures 32 may be stacked so that they create a raised area further along
the
runway. In one aspect, the stacked honeycomb structures 32 may be designed to
have
similar strengths. In another aspect, the stacked honeycomb structures 32 may
be
designed to have varying strengths. For example, there may be provided weaker
honeycomb structures 32A on top for arresting lighter aircraft. Stronger
honeycomb
panels 32B may be provided as bottom or lower layers. All of the layers may be
glued or otherwise adhered to one another via one or more adhesive layers 42.
[0065]
Figure 15 shows a series of fire testing results. Figure 15A shows a
honeycomb cell structure 34 without panels. Figure 15B shows the structure 34
of
Figure 15A with panels 36 secured thereto. These results show that the
honeycomb
structure 32 provides the desired fire resistance. It is possible, however to
provide a
further fire resistant coating to the panel, such as, for example, a coating
of
Temprotex0 or other fire or corrosion resistant material.
[0066]
Another example of a macro-patterned material that may be used
according to this disclosure is a 3-D printed material that is printed in
layers. The
desired macro-patterned material shape may be computer generated and then
printed
using any appropriate material(s). Additional materials may be useable with
the 3-D
printing option. For example, sand or loose pumice (when combined with a
suitable
binder) may be printed into the desired forms. The materials used should
generally
have the crushability parameters described, such that wheels of a moving
aircraft will
cause the material to crush or otherwise deform.
[0067] A further example of a macro-patterned material that may be used
according to this disclosure is a lattice material that is formed via sticks
that are
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connected to one another at various points to create a structure. Non-limiting
examples of such lattice-type structures are shown in Figure 16.
[0068] The
material properties of the lattice structure can be tailored by changing
lattice structure itself, the raw materials, or the size of the material
components.
Changes may also be made in the length, width or diameter of the sticks, the
bonding
strength at the joint points, as well as other parameters. For example, the
compressive
strength may be controlled to be about 3-100 psi, depending on the specific
requirements for a vehicle arresting system application. For example, the
density may
range from about 2-50 pcf. For example, the lattice structure may have a
component
diameter or component cross-section feature size of about 0.001 to about 1.5
inches.
One example of a possible lattice structure is a lattice truss structure.
[0069]
Whether the vehicle arresting system is made from the 3-D folded
materials or the honeycomb structures described, the macro-patterned materials
may
be stacked so that varying layers have varying levels of crushability. In one
example,
core structures may be arranged in a way that allows varying crushability at
varying
levels of the structure. For example, an outer layer may crush more easily
than an
inner layer, so that much of the damage to the structure occurs externally. As
another
example, the outer panel or layer may be scored more heavily or deeply, so
that it
creates more drag load. As another example, an outer layer of the system may
be
provided of different layers of materials having different strengths from
lower
materials in the same system. An optimal combination of these parameters may
result
in the maximum effectiveness of the structure as a vehicle arresting system.
These
features may be tailored for different airport requirements, runway sizes,
and/or
expected size of aircraft to be safely stopped.
[0070] The resulting structures and blocks of bodies formed therefrom may
be
formed into panels, blocks, beds, or any structure that can positioned at the
end of a
runway or road. The resulting vehicle arresting system may be secured in any
appropriate way. The resulting vehicle arresting system may be covered or
coated
with any materials for such purpose.
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[0071] Changes and modifications, additions and deletions may be made to
the
structures and methods recited above and shown in the drawings without
departing
from the scope or spirit of the disclosure or the following claims.
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