Note: Descriptions are shown in the official language in which they were submitted.
CA 02512927 2005-07-22
Title
BALLISTIC RESISTANT DEVICES AND SYSTEMS
AND METHODS OF MANUFACTURE THEREOF
Background of the Invention
[0001] The present invention relates generally to ballistic resistant devices
and systems and
to methods of manufacture of such ballistic resistant devices and systems, and
particularly, to
ballistic resistant devices and systems for use in body armor and to methods
of manufacture of such
ballistic resistant devices and systems.
[0002] Ballistic resistant armor is used in many applications including, for
example,
protection of vehicles and persons from ballistic threats. Body armor to be
worn on a person for
protection from, for example, ballistic threats, has been available for
several decades. In general,
body armor protects vital parts of the human torso against penetration and
severe blunt trauma
from ballistic projectiles. In the development of body armor, there is a
continuing effort to
develop lighter, stronger, thinner, and more durable armor.
[0003] For example, monolithic and multi-component ceramic plates have been
used in a
number of hard body armors (that is, body armors including hard projectile
resistant components
or plates). See, for example, U.S. Patent No. 6,253,655 and Canadian Patent
No. 2,404,739.
U.S. Patent No. 6,253,655 discloses an armor including a durable span cover
for suppressing
debris that would otherwise be ejected from the armor as a result of the
impact of a projectile or
missile on the armor. The span cover of U.S. Patent No. 6,253,655 also
purportedly protects the
ceramic or ceramic-based composite armor panels of U.S. Patent No. 6,253,655
from sustaining
damage when dropped onto a concrete surface. In one embodiment, the armor is a
laminate
including a polymer sheet outer layer, a flexible foam sheet or flexible
honeycomb inner layer, a
ceramic-based armor plate, and a fiber-reinforced plastic laminate backing.
Adhesive layers
bond each of the main layers to its adjacent layer or layers. When the armor
is accidentally
dropped or when an object impacts the polymer sheet outer layer at low
velocity, the impact
CA 02512927 2005-07-22
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force is distributed by the polymer sheet outer layer to the flexible foam
inner layer, which
absorbs some of the kinetic energy. When a ballistic projectile such as a
bullet strikes the
polymer sheet, the projectile perforates the polymer sheet and is defeated by
the armor plate.
The ceramic layer in the armor literally breaks up the projectile; thus,
absorbing a substantial
amount of energy from the ballistic projectile. During the ballistic impact
event, the ceramic will
fracture into small pieces due to the reflective stress wave created by the
impact of the ballistic
projectile. These small pieces of ceramic are called span and the flexible
foam inner layer and
the polymer sheet outer layer keep the resultant span from ejecting out of the
armor.
[0004] Canadian Patent No. 2,404,739 and its corresponding U.S. Patent No.
6,912,944
disclose a ceramic armor system for personnel or vehicles that includes an
integral ceramic plate
or interconnected ceramic components. The ceramic has a deflecting front
surface that includes
one or more deflecting nodes. A shock-absorbing layer is bonded to the rear
surface of the
ceramic plate. The shock-absorbing layer can be formed of a polymer-fiber
composite, including
aramid fibers, carbon fibers, glass fibers, ceramic fibers, or polyethylene
fibers. The shock
absorbing layer can include layers of one type of fiber over another type of
fiber in a suitable
orientation that may be parallel to or at any other angle to one another. A
front span layer can be
provided which is bonded to the front of the ceramic plate. The material
adhered to the back of
the ceramic plate/layer absorbs the residual energy of the ballistic
projectile and also protects the
wearer from blunt trauma created during the ballistic impact.
[0005] In general, ceramic materials used in armor systems are quite rigid and
hard,
while being relatively low in weight as compared to, for example, steel.
Ceramic materials are
also relatively resistant to abrasion, heat, chemical reaction and
compression. Although
substantial protection is provided by currently available body armor including
ceramic plates
from hits by one or a couple of ballistic projectiles, such body armor often
fails upon receiving
several more hits by ballistic projectiles.
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[0006] It is desirable, therefore, to develop improved ballistic resistant
devices that
reduce or eliminate the above-identified and other problems associated with
currently available
ballistic resistant devices.
Summary of the Invention
[0007] In one aspect, the present invention provides a projectile resistant
device for use
in armor including a ceramic component; and at least a first component adhered
to the ceramic
component on at least one side thereof. The first component preferably has a
flexural modulus
of at least 25 Msi and is adhered to a back surface of the ceramic component.
The projectile
resistant device can further include at least a second component adhered to a
front surface of the
ceramic component. The second component preferably has a flexural modulus of
at least 25Msi.
[0008] In one embodiment, the first component comprises a woven carbon fabric
adhered
to a back side of the ceramic component. The first component can also include
at least a first
layer, a second layer and a third layer of a woven carbon fabric. The second
component can also
include a woven carbon fabric.
[0009] In one embodiment, the first layer is adhered to the back surface of
the ceramic
component; the second layer is adhered to the back surface of the first layer,
and the direction of
a weave of the second layer is rotated to be of a different orientation than
the direction of the
weave of the first layer; and the third layer is adhered to the back surface
of the second layer, and
the direction of a weave of the third layer is rotated to be of a different
orientation than the
direction of the weave of the second layer. In one embodiment, the direction
of the weave of the
second layer is rotated approximately 30° about its axis in a first
direction relative to the
direction of the weave of the first layer. In this embodiment, the direction
of the weave of the
third layer is rotated approximately 60° about its axis in the first
direction relative to the direction
of the weave of the first layer.
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[0010] The proj ectile resistant device can further include a retention layer
that is adhered
to the front surface of the second component and covers the front surface of
the ceramic
component. At least a portion of the retention layer extends around the edges
of the other
components (for example, the second component, the ceramic component and the
first
component) and is adhered to the back surface of the projectile resistant
device. The retention
layer is preferably fabricated from a material having a tensile strength of at
least 100 ksi. The
retention layer can, for example, include a woven fiberglass material. In one
embodiment, the
retention layer includes a plurality of portions that extend around the edges
of the other
components and are to be adhered to the back surface of the projectile
resistant device.
[0011] The projectile resistant device can also include a backing component.
Preferably,
the backing component includes a first backing layer which is adhered to the
back surface of the
first component, a second backing layer adhered to the back surface of the
first backing layer,
and a third backing layer adhered to the back surface of the second backing
layer. Each of the
first backing layer and the third backing layer preferably have a stiffness
greater than the second
backing layer. The second or intermediate backing layer preferably exhibits
greater energy
absorption properties than each of the first backing layer and the third
backing layer.
[0012] In one embodiment, the first backing layer comprises multiple laminated
layers of
a first grade of woven high molecular weight polyethylene fibers. The second
backing layer in
this embodiment can include multiple laminated layers of a second grade of
woven high
molecular weight polyethylene fibers. The third backing layer in this
embodiment can include
multiple laminated layers of the first grade of woven high molecular weight
polyethylene fibers.
[0013] The retention layer as described above can be adhered to the front
surface of the
second component to cover the front surface of the second component and
include at least a
portion that extends around the edges of the second component, the ceramic
component, the first
component and the backing layer and is adhered to a back surface of the third
backing
component.
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[0014] The projectile resistant device can further include a protective shell
comprising a
polymeric material. The protective shell can include a front wall. The front
surface of the
retention layer can be adhered to the back surface of the front wall. The
protective shell further
includes side surfaces extending back from the front surface to encompass
sides of the retention
layer, the first component, the ceramic component, the second component and
the backing
component.
[0015] In another aspect, the present invention provides a proj ectile
resistant device for
use in armor including a projectile resistant component comprising a ceramic
component and at
least another component in operative connection with the ceramic component. A
retention layer
is adhered to the front surface of the projectile resistant component. At
least a portion of the
retention layer extends around the edges of the projectile resistant component
and is adhered to
the back surface of the projectile resistant component. The retention layer
preferably includes a
material having a tensile strength of at least 100kpsi. The retention layer
can, for example,
include a woven fiberglass fabric.
[0016] In a further aspect, the present invention provides a projectile
resistant device for
use in armor including a ceramic component; and a backing component in
operative connection
with the rear surface of the ceramic component. The backing component
preferably includes a
first backing layer, a second backing layer adhered to the back surface of the
first backing layer,
and a third backing layer adhered to the back surface of the second backing
layer. Each of the
first backing layer and the third backing layer has a stiffness greater than
that of the second
backing layer. The second backing layer has greater energy absorption
properties than each of
the first backing layer and the third backing layer.
[0017] In still a further aspect, the present invention provides a projectile
resistant device
including a ceramic component. A first component is adhered to a back surface
of the ceramic
component. The first component preferably includes at least a first layer, a
second layer and a
third layer of a woven carbon fabric. Each of the first layer, the second
layer and the third layer
of woven carbon fabric has a flexural modulus of at least 25 Msi. The
direction of the weave of
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the second layer is preferably rotated approximately 30° about its axis
in a first direction relative
to the direction of the weave of the first layer. The direction of a weave of
the third layer is
preferably rotated approximately 60° about its axis in the first
direction relative to the direction
of the weave of the first layer. A second component is adhered to the front
surface of the
ceramic component. The second component preferably comprises at least one
layer of a woven
carbon fabric. The woven carbon fabric has a flexural modulus of at least 25
Msi. A backing
component including a first backing layer is adhered to the rear surface of
the first component.
A second backing layer is adhered to the back surface of the first backing
layer. A third backing
layer is adhered to the back surface of the second backing layer. Each of the
first backing layer
and the third backing layer has a stiffness greater than that of the second
backing layer. The
second backing layer has greater energy adsorption properties than the first
backing layer and the
third backing layer. A retention layer is adhered to the front surface of the
second component.
The retention layer covers the front surface of the second component. A
plurality of portions of
the retention layer extend around the edges of the second component, the
ceramic component,
the first component, and the backing component and are adhered to the back
surface of the
backing component. The retention layer preferably comprises a woven fiberglass
material
having a tensile strength of at least 100 ksi. The proj ectile resistant
device further includes a
protective shell of a polymeric material. The protective shell has a front
wall. The front surface
of the retention layer is adhered to the back surface of the front wall. The
protective shell further
includes side surfaces extending back from the front surface to encompass
sides of the retention
layer, the first component, the ceramic component, the second component and
the backing
component.
[0018] The body armor of the present invention provides substantially improved
multiple-strike resistance as compared to currently available body armor. In
that regard, the
body armor of the present invention can withstand eight 0° obliquity
impacts from a 5.56 mm IP
round at velocities up to 940 m/s and up to five impacts of a 7.62 mm AP round
at velocities up
to 485 m/s. To the knowledge of the present inventors, currently available
body armor can
withstand only three 5.56 rounds and only three 7.62 rounds, respectively.
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Brief Description of the Drawings
[0019] Other aspects of the present invention and advantages thereof will be
discerned from
the following detailed description when read in connection with the
accompanying drawings, in
which:
[0020] Figure 1A is a rear view of an embodiment of a body armor of the
present invention.
[0021] Figure 1B is a side, cross-sectional view of the body armor of Figure
1A.
[0022] Figure 1C is a rear perspective view of the body armor of Figure 1A.
[0023] Figure 1D is an enlarged, side cross-sectional view of the encircled
portion of the
body armor of Figure 1B.
[0024] Figure 1E is a bottom, cross-sectional view of the body armor of Figure
1A.
[0025] Figure 1F is a front view of the body armor of Figure 1A.
[0026] Figure 2A is a front view of an embodiment of a ceramic component of
the body
armor of Figure 1A.
[0027] Figure 2B is a side view of the ceramic component of Figure 2A.
[0028] Figure 2C is a side cross-sectional view of the ceramic component of
Figure 2A.
[0029] Figure 2D is a top view of the ceramic component of Figure 2A.
[0030] Figure 2E is a bottom cross-sectional view of the ceramic component of
Figure 2A.
[0031] Figure 3 is a front view of the three carbon fabric layers of the first
component of
the body armor of Figure 1A.
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g
[0032] Figure 4A is an exploded, perspective view of an embodiment of a mufti-
layer
backing component of the body armor of Figure lA.
[0033] Figure 4B is a front view of the assembled backing layer of Figure 4A.
[0034] Figure 4C is a side, cross-sectional view of the assembled backing
layer of
Figure 4A.
[0035] Figure 5 is a front view of an embodiment of a retention layer of the
body armor of
Figure 1 A.
[0036] Figure 6A is a front view of an outer shell of the body armor of Figure
lA.
[0037] Figure 6B is a side, cross-sectional view of the outer shell of Figure
6A.
[0038] Figure 6C is a rear perspective view of the outer shell of Figure 6A.
Detailed Description of the Invention
[0039] In general, the ballistic resistant devices of the present invention
are well suited to
protect vital portions of the human torso against penetration and severe blunt
trauma as can, for
example, be caused by small caliber rounds and armor piercing projectiles.
Unlike currently
available ballistic resistant devices, the ballistic resistant devices of the
present invention are
particularly suited to sustain multiple hits from ballistic threats. In
several studies of the ballistic
resistant devices and body armor of the present invention, the ballistic
resistant devices defeated
eight 5.56 mm rounds at point blank range and five 7.62 mm armor piercing
rounds at a range of
250 meters.
[0040] In the embodiment illustrated in Figures 1-6C, armor 10 includes a
ballistic
plate 20 of a ceramic material as the primary projectile-stopping component.
In the illustrated
embodiment, a monolithic, curved ceramic component or plate 20 (see Figures 1D
and 2A-2E)
was used that matched generally the curved contour of the human torso. In one
embodiment of
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the present invention, a 98% pure alumina ceramic material was used in ceramic
component 20.
Several currently available armor systems including ceramic components or
plates use silicon
carbide or boron carbide ceramic composites, which, although harder than
alumina ceramic
materials, cost up to 10 times that of alumina. Other currently available
armor systems including
ceramic components or plates use alumina plates of less purity than that used
in the armor of the
present invention. Use of an alumina ceramic having a purity less than the
purity of the alumina
ceramic of the present invention, would require a greater thickness of ceramic
component to
provide an equivalent projectile stopping ability, which increases the size
and weight of the
integrated ballistic plate. Preferably, alumina of at least approximately 98%
purity is used in
armor 10 of the present invention. Use of such alumina ceramic material
provides the advantage
of lower weight for the same ballistic performance versus armor which uses
alumina of lesser
purity.
[0041] In one embodiment, a component including at least one layer 30 (see
Figure 1D)
of relatively hard material (such as a plain woven carbon fabric) was adhered
to a front (strike)
surface of ceramic component 20 using an adhesive 40 such as an epoxy
adhesive. In the
illustrated embodiment, another layer 50 of a relatively hard material was
adhered to a back
surface of ceramic component 20. Preferably, the materials) for front layer 30
and back layer 50
have a flexural modulus or stiffness and number of filaments of at least 25
Msi (or 25,000,000
psi) and at least 3000 filaments per strand of yarn, respectively. More,
preferably the materials)
have a modulus of at least 33 Msi and at least 6000 filaments per strand of
yarn. The stiffness or
modulus of the carbon fabric is much higher than other woven fabric such as
polymer-fiber
composite, fiberglass and aramids by weight. This stiffness assists in
providing the appropriate
support for the back of the ceramic component or plate. The stiffness of each
of the carbon
layers is significant in that it must hold the ceramic together during
multiple ballistic impacts.
As described above, the number of filaments per strand of yarn is preferably
at least 3000.
However, 6000 filaments is more preferred because the resulting carbon fabric
layer will have a
higher ratio of carbon filaments to epoxy; thus, improving the stiffness on a
per weight basis.
The weave of the carbon fabric can, for example, be twill, a plain, a
unidirectional, or a basket
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weave. Preferably, the weave is either plain or twill. The carbon fabrics used
in several studies
of the present invention were obtained from Barrday, Inc. of Ontario, CA
[0042] In one embodiment, layer 50 included three layers or sheets 52, 54 and
56 (see,
for example, Figures 1D and 3) of twill weave carbon fabric. Layer 50 was
adhered to a back
surface of ceramic plate 20 using an adhesive 60 such as an epoxy adhesive.
Layers 52, 54 and
56 were adhered to each other using adhesive layers 57 and 58 such as an epoxy
adhesive. The
adhesive chosen for several studies was a high peel strength rubber toughened
epoxy. The
adhesive (for example, epoxy) used between the carbon fabric layers preferably
has a peel
strength of greater than 50 PIW (pounds per inch width, as per ASTM D1876-
61T). Peel
strengths lower than 40 PIW can reduce the multi-hit performance. Front layer
30 and back
layer 50 were found to function together to reinforce ceramic plate 20 and
reduce crack
propagation during multiple ballistic impacts. Front layer 30 and back layer
50 enabled a single
alumina ceramic plate to withstand a higher number of multiple hits from a
ballistic projectile as
compared to ceramic plates provided in currently available body armor.
[0043] In a preferred embodiment, the weave of each of layers 52, 54 and 56 of
carbon
fabric of back layer 50 is oriented differently. In that regard, during
assembly of several body
armors 10 studied in the present invention, the weave direction of each layer
52, 54 and 56 of
carbon fabric was rotated approximately 30° relative to the weave
direction of the adjacent layer.
In that regard, if the orientation of the weave of layer 52 was defined as
approximately 0°, the
orientation of layer 54 was approximately 30° and the orientation of
layer 56 was approximately
60°. Orienting the weaves of layers 52, 54 and 56 in this fashion
caused the carbon fabric
assembly or back layer 50 to have an acoustical impedance characteristic which
sufficiently
matched that of ceramic component 20; thereby reducing rebounding pressure
waves which
damage the ceramic around the impact point and produce ejected span. By
mitigating such
damage to the ceramic component 20, contact time between the projectile and
the ceramic (also
known as dwell time) is increased allowing the ceramic to better erode the
proj ectile and reduce
its velocity; thus enhancing the overall stopping power of the armor 10
without adding a
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significant amount of weight. Rotating the orientation of the weave of each
layer 52, 54 and 56
of carbon fabric increased the stiffness of back layer 50; thus, increasing
the ability of back
layer 50 to support ceramic component 20 during ballistic impact. During
multiple ballistic
impacts, front layer 30 and multi-oriented, composite carbon back layer 50
reduced crack
propagation from one impact zone to another. Prior to the present invention,
certain non-ceramic
layers were included in armor in addition to the ceramic component to, for
example, minimize
crack propagation and span or absorb shock. However, such non-ceramic layers
did not provide
a substantial increase in overall projectile stopping power. In addition to
reducing crack
propagation, carbon fabric front layer 30 and carbon fabric back layer 50 of
the present invention
enable the thickness of ceramic component 20 to be decreased (thereby reducing
overall weight),
while accomplishing the task of preventing multiple projectiles from
penetrating armor 10.
[0044] Armor 10 can also include a backing component or panel 70 (see Figures
ID and
4A-4C) fabricated from multiple layers of one or more materials. Backing panel
70 is adhered to
the back surface of the back layer 50 using an adhesive 80 such as urethane
adhesive. Backing
pane170 functioned, in part, to provide additional projectile stopping
capacity and to catch
debris/spall liberated from the armor assembly during a proj ectile impact.
The peel strength
between the layers of ballistic fabric in backing panel 70 (discussed further
below) is important
and the ultimate stiffness of backing panel 70 can affect the multi-hit
capability of ceramic
component 20 and, ultimately, the system. The peel strength of adhesive
between the layers of
fabric in several of the studies of the present invention was between
approximately 4 psi, and 10
psi. To reduce and preferably minimize blunt trauma to the torso of the person
equipped with
armor 10, backing panel 70 also preferably functions to distribute the impact
force over a wider
area than the tip of the projectile.
[0045] In one embodiment, multiple layers or sheets woven from ultra-high
molecular
weight polyethylene material such as SPECTRA~ 900 available from Honeywell of
Virginia,
USA were used. In one such embodiment, the woven sheets were SPECTRA SENTINEL~
fabric (woven quasi-unidirectional, ballistic resistant fabrics used in
combination with a resin
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system for soft or hard armor) available from Barrday, Inc. of Ontario,
Canada. As illustrated in
Figure 4A, in one embodiment, backing panel 70 included multiple sheets of two
different grades
of SPECTRA SENTINEL materials which were heated, stacked and pressed together.
In the
embodiment illustrated in, for example, Figure 4A, a layer 72 including 18
layers 72a of
SPECTRA grade 0, a 6.3+/- .3 oz/yd2 fabric, were sandwiched between two layers
74 and 76 of
SPECTRA grade 1, a 3.7+/- .4 oz/yd2 fabric, material. Each of layers 74 and 76
included 16
layers 74a and 76a of SPECTRA grade 1. The two different grades of material in
layers 72, 74
and 76 provided two different stiffnesses. Layer 74 (SPECTRA grade 1)
preferably exhibits a
higher stiffness which makes it highly effective in stopping a projectile that
has penetrated front
layer 30, ceramic component 20 and back layer 50. Likewise, layer 76 (SPECTRA
grade 1) also
preferably exhibits a higher stiffness which makes it highly effective in
stopping a proj ectile that
has additionally penetrated layer 74 and layer 72. Intermediate layer 72
(SPECTRA grade 0) is
less stiff, but provides greater energy absorption (for example, via
delamination) than layers 74
and 76. Layer 72 operates to slow debris and to absorb momentum. Once again,
rear layer 76
(SPECTRA grade 1) material, with its higher stiffness, absorbs any remaining
impact energy and
distributes the force over a wide area; thus ultimately reducing blunt force
trauma to the wearer.
Backing panel 70 thereby offers additional ballistic performance enhancement
with the addition
of little weight. Test data for the present invention showed that performance
is enhanced with the
described sandwich configuration beyond that obtained by other stacking of
such materials, for
example, a simple one-for-one (that is, grade 1/grade 0/grade 1/grade 0, etc)
layering or 18/32
(18 grade 1 layers over 32 grade 0 layers) stacking. The 18/32 stack for
example has a different
impedance than the 16/18/16 embodiment. The impedance or modulus of backing
panel 70
further aids in supporting the ceramic plate and ultimately the armor system.
[0046] The unique stacking arrangement of backing pane170 results in impedance
variations selected to work against the changing requirements of a ballistic
event as it progresses
through armor 10. Backing layers (that is, layers of material to the rear of a
ceramic component)
in currently available armor including a ceramic component are designed only
to capture exiting
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span and to distribute force. Such currently available armor relies solely
upon the ceramic
component to stop the projectile.
[0047] In one embodiment, woven fiberglass retention layer or component 90
(see, for
example, Figures 1C, 1D and 5) was adhered to the front surface of the front
layer 30. Retention
layer 90 preferably functions, in part, to slow and capture span (debris
liberated from the front
surface of armor 10 during a ballistic impact). Spall, if not deterred, poses
the threat of injury to
anyone close to armor 10. Spall of a size or velocity that does not penetrate
a .6-mm thick sheet
of 3003 H14 aluminum would not likely cause serious injury. Fiberglass
retention layer 90 in the
present invention was found to stop span resulting from the impact of a
7.62mmX51 mm FMJ
Ball Round traveling at 660 m/s. Spall mitigation layers are common in
ballistic armor.
However, in the present invention, fiberglass retention layer 90 has a
secondary function. In that
regard, fiberglass retention layer 90 was dimensioned to wrap around other
components (that is,
front component 30, ceramic component 20, back component 50 and backing layer
70) to assist
in maintaining the overall integrity of the armor. Retention layer 90
preferably includes a
plurality of portions or flaps 92 that extend around the edges or sides of
front component 30,
ceramic component 20, back component 50 and backing component 70 and were
adhered to a
back surface of backing component 70 using, for example, a urethane adhesive
96. In several
studies of the present invention, fiberglass retention layer 90 was preferably
between
approximately 0.010 and 0.020 inches thick. More preferably, fiberglass
retention layer 90 was
between approximately 0.015 and 0.020 inches thick.
[0048] The advantage provided by this configuration was apparent when the
armor 10
was subjected to multiple ballistic impacts. Being wrapped within fiberglass
retention layer 90,
the projectile-stopping components and backing layer 70 were held tightly
together or retained
against the repeated ballistic impact forces which act to separate the
projectile-stopping
components from backing layer 70. Furthermore, a significant portion of the
projectile's energy
is redirected into overcoming the relatively high sheer and tensile strength
of the bonded
fiberglass layer 90, thereby allowing a greater number of impacts before armor
10 is too badly
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damaged to provide effective protection. A high sheer strength urethane
adhesive 96 was used to
bond fiberglass retention layer 90 to front layer 30 and to backing layer 70.
The peel strength of
the adhesive 96 used to bond retention layer 90 to other layers is preferably
at least 10 psi, more
preferably at least 16 psi and, more preferably, at least 32 psi.
[0049] Retention layer 90 can be fabricated from materials other than woven
fiberglass.
Preferably such materials exhibit a relatively high tensile strength as
described above. In that
regard, materials for retention layer 90 preferably have a tensile strength
(the maximum tensile
stress that may be sustained before a material will rupture) of at least 100
ksi (or 100,000 psi).
More preferably, the material of retention layer 90 has a tensile strength of
at least 150 ksi. Even
more preferably, the material of retention layer 90 has a tensile strength of
at least 200 ksi. The
weave of the material for retention layer 90 can, for example, be a plain,
twill, or basket weave;
and is preferably, a twill weave. The weave type for retention layer 90 is
important because a
stiff weave or a weave with low drapeability will not wrap around the armor
system components
appropriately. The type of fiberglass used in several studies of the present
invention was an e-
glass. However, other fiberglass such as s-glass can also be used. The s-glass
tensile strength is
higher than the e-glass tensile strength, but it is typically more expensive.
The material of
retention layer 90 (for example, fiberglass) preferably exhibits an elongation
in the range of
approximately 2-5%. More preferably, the elongation is approximately 3%.
[0050] In general, the integrity of currently available armor is lost
relatively quickly as a
result of delamination caused by multiple ballistic impacts. The ability of
such currently
available armor to stop projectiles and to distribute load is thereby severely
decreased. To the
contrary, in the armor 10 of the present invention, the wrapping of retention
layer 90 provides
improved resistance against delamination by requiring the projectile's energy
to also overcome
the sheer and tensile forces provided by retention layer 90.
[0051] A preformed outer shell 110 (see, for example, Figures 1D and 6A-6C)
encompassed the front and sides of the other components of armor 10. In one
embodiment, a
pre-formed etched or non-filler type polycarbonate outer shell 110,
approximately 1/32" thick,
CA 02512927 2005-07-22
was adhered to fiberglass retention layer 90 using an adhesive 120 such as a
urethane adhesive.
Shell 110 was shaped to conform to the compound contours of ceramic component
20 and
included side walls around the periphery thereof which extend back or rearward
to cover the side
edges of the components of armor 10. During assembly, shell 110 acts as a
fixture or form to
hold the other components of armor 10 in place as they were added to the
assembly and as the
armor assembly was pressed. During use of armor 10, shell 110 also protects
the front and side
edges of the other components of armor 10 against abrasion and incidental
puncture or snagging.
The peel strength of adhesive 120 used to bond the shell 110 to retention
layer 90 is preferably at
least 10 psi, more preferably at least 16 psi and, even more preferably, at
least 32 psi. Adhesion
of , for example, urethane can be improved by etching the polycarbonate prior
to bonding.
[0052] The integration of the components of armor 10 was accomplished through
the use
of compression molding without heating.
[0053] Although the present invention has been described in detail in
connection with the
above embodiments and/or examples, it should be understood that such detail is
illustrative and
not restrictive, and that those skilled in the art can make variations without
departing from the
invention. The scope of the invention is indicated by the following claims
rather than by the
foregoing description. All changes and variations that come within the meaning
and range of
equivalency of the claims are to be embraced within their scope.
