Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: LIGHT-WEIGHT SEMI-RIGID COMPOSITE ANTI-
BALLISTIC SYSTEMS WITH ENGINEERED COMPLIANCE
AND RATE-SENSITIVE IMPACT RESPONSE
CROSS-REFERENCE TO RELATED APPLICATION
[0001]
This application claims priority to U.S. Provisional Patent Application
Serial No. 61/780,803, filed March 13, 2013, which is incorporated herein in
its entirety.
FIELD OF THE INVENTION
[0002]
This application relates in general to fiber-reinforced products and in
particular to improved composite anti-ballistic systems comprising stacked
arrangements of
sub-laminates.
BACKGROUND OF THE INVENTION
[0003]
Current anti-ballistic personal protection is generally by either common
Small Arms Protective Insert (SAPI) armor plates or by conventional soft
vests. Rigid
ceramic SAPI plates provide effective protection, but they limit mobility and
are
uncomfortable, which can distract soldiers in the field and induce unnecessary
rapid fatigue.
[0004] Additionally,
SAPI plates are very susceptible to serious damage due to
impacts endemic to a soldier's operations in the field; and the damage is
difficult to detect,
impossible to repair and can result in serious or total degradation in
ballistic protection. SAPI
plates also have poor protection against closely-spaced multiple hits.
[0005]
Therefore, new anti-ballistic systems are desirable. In particular need are
new anti-ballistic personal protection systems that feature controlled
rigidity under ballistic
impact to provide the necessary functions of anti-penetration, load spreading,
impact energy
management and shock management.
SUMMARY OF THE INVENTION
[0006] In
various embodiments, an improved composite anti-ballistic system is
disclosed. More particularly, this disclosure relates to composite anti-
ballistic systems
comprising composite materials of varying properties. In various embodiments,
composite
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anti-ballistic devices are disclosed. In various embodiments of the present
disclosure, an
antiballistic system comprises multiple nested sub-laminates manufactured from
layers of
unidirectional monofilaments.
[0007] In
various embodiments of the present disclosure, an antiballistic system
comprises engineering fibers having anti-ballistic properties. In various
embodiments, an
antiballistic system comprises polymer matrix materials and interfacial
materials engineered
for controlled compliance, deformation, and energy release, along with rate
sensitive
behavior.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows
a diagrammatic view illustrating at least one composite
laminate material according to an embodiment of the present disclosure;
[0009]
FIG. 2 shows an enlarged detail view of area "A" of FIG. 1 in accordance
with the present disclosure;
[0010]
FIG. 3 shows a data graph, illustrating percent performance vs. number of
layers, in accordance with the present disclosure;
[0011]
FIG. 4 shows a diagrammatic view, illustrating flexibility of at least one
panel of such at least one composite laminate material, in accordance with the
present
disclosure;
[0012]
FIG. 5 shows a diagrammatic view, illustrating impact loading of at least
one panel of such at least one composite laminate material, in accordance with
the present
disclosure;
[0013]
FIG. 6 shows a diagrammatic view, illustrating a comparative thickness of
at least one panel of such at least one composite laminate material, in
accordance with the
present disclosure;
[0014] FIG. 7 shows
a diagrammatic view, illustrating intra-laminar hybridization,
in accordance with the present disclosure;
[0015]
FIG. 8 shows a diagrammatic view, illustrating comingled filaments, in
accordance with the present disclosure; and
[0016]
FIG. 9 shows a graphical representation of the change in impact load
through use of sub-laminates and interlayers in accordance with various
embodiments of the
present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
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[0017] The
following description is of various exemplary embodiments only, and
is not intended to limit the scope, applicability or configuration of the
present disclosure in
any way. Rather, the following description is intended to provide a convenient
illustration for
implementing various embodiments including the best mode. As will become
apparent,
various changes may be made in the function and arrangement of the elements
described in
these embodiments without departing from principles of the present disclosure.
[0018]
TABLE 1 provides a glossary of terms and definitions that may be used in
various portions of the present disclosure.
TABLE 1: BRIEF GLOSSARY OF TERMS AND DEFINITIONS
Adhesive A resin used to combine composite materials.
Not isotropic; having mechanical and or physical properties which
Anisotropic
vary with direction at a point in the material.
The weight of fiber per unit area, often expressed as grams per square
Areal Weight
meter (g/m2).
A closed vessel for producing a pressurized environment, with or
Autoclave without heat, to an enclosed object, which is undergoing
a chemical
reaction or other operation.
Generally defined herein as an intermediate stage in the reaction of
B-stage some resins. Materials are sometimes pre-cured to this
stage, called
"prepregs", to facilitate handling and processing prior to final cure.
Final stage in the reaction of certain resins in which the material is
C-Stage
relatively insoluble and infusible.
To change the properties of a polymer resin irreversibly by chemical
Cure reaction. Cure may be accomplished by addition of curing
(cross-
linking) agents, with or without catalyst, and with or without heat.
Unit of the linear density of a continuous filament or yarn, equal to
Decitex (dtex)
1/10th of a tex or 9/10th of a denier.
The smallest unit of a fiber-containing material. Filaments usually are
Filament
of long length and small diameter.
An organic material composed of molecules of monomers linked
Polymer
together.
A ready-to-cure sheet or tape material. The resin is partially cured to
Prepreg
a B-stage and supplied to a layup step prior to full cure.
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Tow A bundle of continuous filaments.
Ultra-high-molecular-weight polyethylene. A type of polyolefin made
UHMWPE up of extremely long chains of polyethylene. Trade names
include
Spectra and Dyneema0.
Unidirectional tape (or UD tape) ¨ flexible reinforced tapes (also
referred to as sheets) having uniformly-dense arrangements of
Unitape reinforcing fibers in parallel alignment and impregnated
with an
adhesive resin. UD tapes are typically B-staged and can be used as
layers for the composites herein.
[0019] As described in more detail herein below, light-weight semi-rigid
composite anti-ballistic systems in accordance with the present disclosure
comprise multiple
nested sub-laminates. Sublaminates may be manufactured, for example, from
layers of
unidirectional monofilaments made from engineering fibers with anti-ballistic
properties
embedded in polymer matrix materials and interfacial materials engineered for
controlled
compliance, deformation, energy release and rate sensitive behavior.
[0020] In
various embodiments, flexibility is gained by splitting the armor up into
many sub-laminates that can move independent of each other that may be
connected with
foam, viscoelastic, static forces, Vanderwall forces, blocking, or rate
stiffing materials, or
nothing at all.
[0021] In
various embodiments of the present disclosure, these layers can be
oriented in multiple directions to distribute the impact loads, control
deformation and
dissipate impact energy to provide ballistic protection in a form that has
sufficient, controlled
rigidity under ballistic impact to provide the necessary functions of anti-
penetration, load
spreading, impact energy management and shock management. Such orientation of
layers can
further provide sufficient flexibility and compliance when worn such that loss
of mobility and
range of motion is minimized, and wearer comfort is improved. These
improvements can
enhance combat effectiveness and minimize operator fatigue due to reduced
mobility and
restriction of range of motion encountered with rigid SAPI plates.
[0022]
Although the system according to the present disclosure may be integrated
into a system also utilizing a ceramic or metallic component, the pure
composite
implementation of the system is not susceptible to impact damage like observed
in a ceramic
SAPI plate and is insensitive to most normal in-service incidental impacts.
The system also
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exhibits superior protection against multiple close spaced hits. Since the
system does not
absorb significant percentages moisture, the resulting anti-ballistic system
does not gain
weight or become water-logged due to hydrolysis. The system also is protected
from
degradation due to flex fatigue, UV radiation and exposure to most agents or
chemicals
normally encountered.
[0023] In
various embodiments, a system in accordance with the present disclosure
comprises at least one composite anti-ballistic device. Such at least one
composite anti-
ballistic device may comprise improved compliance stretchability and
flexibility for higher
mobility and less range-of-motion-restriction by using at least one multi-
layer, multi-
directional sublayer construction.
[0024]
Such at least one flexible ballistic panel can be made from layers of sub-
laminates. The sub-laminates of the panel system can be manufactured from
layers of
unidirectional monofilaments of engineering fibers having antiballistic
properties, a modulus
greater than 1.0 x 106 psi and a failure strength in excess of 100,000 psi.
[0025] Such at least
one multi-layer, multi-directional sub-laminate approach can
use thin (e.g. less than 6 monofilament diameters for conventional
monofilaments, less than
0.005" for ultrathin or nano-monofilaments, ropes, yarns, fibers)
unidirectional tape
("unitape") layers, or alternatively, intra- or inter-laminar hybridization of
filaments. A
unidirectional tape is a fiber-reinforced layer having thinly spread parallel
monofilaments
coated by a resin. In various embodiments, each unitape layer having parallel
fibers is
inherently directionally oriented, in a dedicated direction, to limit stretch
and provide strength
in such chosen direction. In various embodiments, a two-direction unitape
construction may
feature the first unitape layer disposed at a 00 orientation and the second
unitape layer
disposed at a 90 orientation. In the same manner, various one-direction
configurations, two-
direction combinations, three-direction combinations, four-direction
combinations, and other
unitape combinations, may be applied to create laminates having a desired
directional or non-
directional reinforcement.
[0026] In
various embodiments, filaments can comprise various engineering fibers
with a Young's Modulus of over 1 msi and an ultimate tensile strength of more
than 100 KSI.
Such engineering fibers include, but are not limited to: UHMWPE (available
under the trade
names Dyneema0 and Spectra ), Aramid (available under the trade names Kevlar0
and
Twaron0), PBO fiber under the Zylon0 name, liquid crystal polymer VectranO,
glass fibers
such as E and S glass, M5 fibers, carbon and para-aramid under the Technora0
name. In
various embodiments, monofilaments are extruded.
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[0027] In
various embodiments, sub-laminates of the panel system comprise at
least two unidirectional tapes, each having extruded monofilaments therein,
all of such
monofilaments lying in a predetermined direction within the tape, wherein such
monofilaments have diameters less than about 60 microns and wherein spacing
between
individual monofilaments within an adjoining strengthening group of
monofilaments is
within a gap distance in the range between abutting and/or stacked
monofilaments up to about
300 times the monofilament major diameter.
[0028] In
various embodiments, sub-laminates further comprise a set of other
laminar overlays. In various embodiments, a sub-laminate comprises a first one
of such at
least two unidirectional tapes includes monofilaments lying in a different
predetermined
direction than a second one of such at least two unidirectional tapes.
[0029] In
various embodiments, a sub-laminate comprises a combination of the
different predetermined directions of such at least two unidirectional tapes,
and these
directions are user-selected to achieve sub-laminate properties having planned
directional
rigidity/flexibility. Such a user-planned arrangement can provide a sub-
laminate comprising a
three-dimensionally shaped, flexible composite part. In addition, sub-
laminates may comprise
multiple laminate segments attached along peripheral joints. In various
embodiments, a sub-
laminate comprises at least one laminate segment attached along peripheral
joints with at
least one non-laminate segment. Further, a sub-laminate may comprise multiple
laminate
segments attached along area joints.
[0030] In
various embodiments, a sub-laminate comprises at least one laminate
segment attached along area joints with at least one non-laminate segment. In
various
embodiments, a sub-laminate comprises at least one laminate segment attached
along area
joints with at least one unitape segment. In various other embodiments, a sub-
laminate
comprises at least one laminate segment attached along area joints with at
least one
monofilament segment. In various embodiments, a sub-laminate may comprise at
least one
rigid element.
[0031] In
various embodiments, engineering fibers can further include nano-
filaments, nano-ropes, nano-yarns, nano-tows, nano-powder, and/or nano-film
that may be
incorporated into the unitape layer, associated with the unitape, and/or
applied to the outer
surface of the unitape. Such at least one nano-material may be applied to the
outer surface of
individual monofilaments by nano-spray, electron beam deposition, sputtering,
vapor
deposition, atmospheric plasma deposition, infusion, or as part of polymer
coating. Such
coating may comprise a cross-linking system with thermal activation, or
alternately two-part
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self-curing, or alternately radiation cured such as E-beam, RF cured, UV
cured, or
alternatively, heat cured. The surface of the fibers, the surface of the nano-
component and/or
the polymer resin may all be provided with chemically reactive functional
groups that create
a strong chemical bond between the monofilament surface, the nano-component,
the short
fiber component or the resin, to improve adhesion and enhance energy
dissipation.
[0032]
Individual unitape plies may vary from 1.5-80 g/m2 of areal density. In
various embodiments, a unitape can contain one single class of fibers such as
Aramid,
UHMWPE, glass, and the like, or alternately contain a combination of classes
or styles (same
class of fiber but different spec for example), or alternately contain any
combination of the
above, such as in a predetermined pattern or configuration. The different
fiber types may be
discrete alternating sets of each material across the width or thickness of
the unitape or they
can be distributed in a uniform intermixed or comingled configuration. These
unitapes may
be layered to produce any combination of materials within each layer of the
sub-laminate.
Examples are having a sub-laminate made from only one grade of monofilament in
each
unitape in the sub-laminate, or by using one or more different unitapes in the
sub-laminate
wherein each unitape is made from one type of monofilament. Another example is
having a
unitape made up of hybrid unitape with multiple fiber types incorporated in
each layer but
having all the unitape in the sub-laminate made from the same specification of
hybrid. Yet
another example is the most general where the sub-laminate is made from
unitapes with
multiple mixes of fiber in the unitape and multiple types of unitape used to
make up the sub-
laminate.
[0033]
Individual unitapes within a sub-laminate may be made from differing fiber
areal densities. Hybrid sub-laminates of this kind can provide improved
ballistic performance
when one of the types of fiber may provide superior protection under some
conditions but
may not provide adequate protection under another set of conditions. A good
example would
be the use of UHMWPE monofilaments, which provide excellent anti-ballistic
protection
under most conditions but are limited in their ability to protect against some
impacts by
incendiary projectiles that exceed temperature limits of the base polymer.
Aramid or PBO
hybrids can improve the ability of the UHMWPE base laminate to protect against
the
incendiary projectile due to the higher temperature capabilities of the aramid
or PBO
monofilaments. Using monofilaments of dissimilar properties can also improve
the ballistic
impact performance because the interactions of the dissimilar monofilaments
can generate
significant impact energy absorption, shock dissipation and controlled
deformations due to
the incompatibility of strains between the dissimilar monofilaments.
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[0034] In various embodiments, the minimum number of plies within a sub-
laminate can be determined by semi-empirical methods that find the approximate
number of
plies needed to bring the specific ballistic performance of the sheet up to
the level most
comparable to the monolithic plate case by obtaining the optimum "lamination
effect." At a
certain number of unitape layers, the improvement in ballistic performance
levels off (as
illustrated in FIG. 3), and the number of plies is determined by the use of a
sub-laminate
thickness that provides the degree of flex desired.
[0035]
Each unidirectional ply can be oriented in any given in-plane angle. The
simplest is a two-direction, cross-ply [0 /90 ] configuration, which is easy
to fabricate but
often does not provide the best ballistic protection or the best resistance to
global panel
deformation nor to "back wall deformation." Back wall deformation is the area
directly under
the impact area where the laminate is extruded & pushed back into the body of
the wearer,
which can cause injury or incapacitation. Excessive deformation also degrades
the ballistic
protection for multi-hit impacts closely spaced. For this reason it is
desirable to have a
number of angles selected. Three provide some improvement but four angles
spaced at the
0 /45 /90 /-45 orientations gives the better performance. Some additional
improvement can
be obtained by adding another set of ply angles such as at 22.5 increments
(0 /22.5 /45 /67 /90 /-67 /-45 /-22.5 /0 for example), or at +/- 30 or +/-60
. The sub-
laminates can be made of stacked repeating sets of these ply groups to build
up the desired
number of unitape layers in order to achieve the required ballistic
performance and flexibility.
[0036] In various embodiments, the resin content can range from 1% to 30% of
the
total areal weight of the unitape with the lower resin contents generally
providing better
ballistic performance. High and low resin content unitape can be combined in
various
stacking sequences and layup patterns.
[0037] Thin layers
of polymer films, non-wovens, and layers of nano-fibers or
films can be located at one or more unitape interfaces to improve or modify
ballistic
performance.
[0038]
Resin materials may comprise epoxy base, cyanate ester base, or polyester
based resins of varying molecular weight or composition combined with various
curing
agents to provide the desired matrix properties. Matrix materials may also be
thermoplastic
polyurethane, alternately block copolyesters, alternately two part
polyurethane either with the
aromatic or aliphatic isocyanate curing mechanism, alternately ceramics,
alternately E-beam
deposition polymers, alternately silicones, or others. Resins may be a hot
melt, alternately
aqueous solutions, alternately solutions with organic or inorganic solvent,
alternately water or
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solvent dispersions, alternately powders, alternately spun-bonded films,
alternately extruded
sheets, alternately cast sheets. The cast or extruded sheets may be
homopolymer, alternately a
multilayer co-extrusion, alternately co-cast onto a carrier, film, paper, or
cloth or the film
may be unsupported.
[0039] In various
embodiments, at least one multilayer, multidirectional sub-
laminate can comprise unitape of pultruded monofilaments such as to provide
the laminate
with a multidirectional-layered network.
[0040] The bending stiffness of a ballistic plate or sheet, neglecting effects
of
transverse strain, is proportional to the section modulus of the plate or
sheet, and may be
calculated according to the formula:
Section Modulus = Z = BD2/6
where B is the width and D is the thickness of the plate or sheet.
[0041] For
comparison purposes only, the width can be normalized to 1 to
determine the effects of the sheet or plate thickness on the flexibility of
comparable plates
and sheets. One inch is a common thickness for composite sheets because it
roughly gives 5
lbs/ft2. For the 1" plate section, the modulus = Z = BD2/6 = (1) (1)/6= 1/6.
The effect on
flexibility by moving to thinner materials can be calculated, starting at
0.020" and going up in
0.020" increments to 0.10". Z = (1) (1/50)2/6 = 11(6) (2500). Therefore,
0.020" = 1/2500 of
the bending stiffness of the 1" plate since Z is proportional to the thickness
of the panel
squared. If t = 0.030, then Z = 1/1111. If t = 0.040, then Z = (1/25)2.
[0042] For
a 1" stack of the 0.020" sheets, the total flex equals the sum of section
modulus: Zeff = E 2i (Z x 50) 1/2500 * (50) = 1/50; and I=1 to 33.3; Zeff = E
2i = 1/33.3. As
seen from this pattern, the flexibility of a panel made up of sub-laminates of
equalizing total
thickness, if all sub-laminate thicknesses are the same proportion using this
relationship, the
total desired panel thickness can be broken down into a number of sub-
laminates that provide
the necessary increase in flexibility. If a thickness of 0.020" is chosen for
the sub-laminate
sheet, then the effective stiffness is 1/50 times lower since the bending
stiffness of the stack
of 50 0.020" sub-laminates is 50 times less than a monolithic 1" ballistic
plate.
[0043] If engineered properly, a panel made from sub-laminates may have
performance ranging from minimal reduction in ballistic performance to
actually being
higher in ballistic protection than solid rigid plates, while still being
flexible. The sub-
laminate may be used as discrete sheets with maximum flexibility or they may
be lightly
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bonded together with a thin layer of compliant rate-sensitive dilation
material embedded in
compliant foam.
[0044]
Bonding the sub-laminate together in such a way decreases the flexibility of
the panel but may still allow for a compliant panel, especially if the panel
does not need to
undergo large deformations as is the case with ballistic plates. In various
embodiments, a
ballistic plate should impart just enough "give" into the panel to provide the
necessary level
of mobility and comfort. This is a subjective parameter that depends upon the
total thickness
of the ballistic panel system, the properties of the monofilament in the sub-
laminate and the
degree of compliance engineered at the interfaces between the laminates.
[0045] Although the
sub-laminate system has sub-engineered flexural properties,
much of the flexibility is due to the low shear and Young's modulus of the
viscoelastic
dilatory foam materials at the interface, bonding the sub-laminate panels into
a single panel.
Dilatory materials are very rate-sensitive and undergo a transition from
highly compliant
elastomeric material to highly rigid, solid material. Under impact, the rate
of sensitive
dilatory layers converts from a soft compliant material into a stiff
interlayer that locks up the
sub-laminates together so that they act as a solid panel, which means that
impact stiffness of a
panel increases to close to that of a solid ballistic panel.
[0046] The
rigidness of the panel under impact spreads the impact loads and
maintains the structural integrity of the panel during the impact. Since this
is a viscoelastic
effect, the rate at which the interlayers transform from soft to rigid can be
controlled to
manage the impact and spread the force of the impact event over a longer
period of time.
Spreading the impact load over a longer time period reduces the magnitude of
the impact
loads, and the load rate can be adjusted to provide optimal load transfer to
the individual sub-
laminates to provide the highest level of protection from each individual
ballistic sub-
laminate.
[0047]
With reference now to FIG. 1, an embodiment of a antiballistic panel 100 is
illustrated in cross-section. The panel comprises compliant, viscoelastic
interlinear layers of
rate-sensitive, higher rate stiffening polymer and polymer foam, between
layers of composite
sub-lamina. A section of the panel 100, labeled "A," is magnified in FIG. 2 to
more clearly
show an embodiment comprising alternating layers of flexible composite sub-
laminate and
stiffening polymer or polymer foam.
[0048]
FIG. 4 is a diagrammatic illustration of the flexibility of panel 100 under
normal use due to the layering of flexible sub-laminates.
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[0049]
FIG. 5 illustrates the resistance of the panel 100 to an impact force (e.g.
from the triangular projectile illustrated). Under impact loads, the rate-
sensitive interlace
rigidizes or "freezes" the plate 100 into the equivalent of one-piece panel
with no sub-
laminate structure.
[0050] At least one
area of design flexibility on the sub-laminate panels is the
ability to select the thickness of the viscoelastic, dilation interlayers. The
most effective of the
commercial systems are in the form of lightweight foams that allow for the
incorporation of
relative thick layers with minimal weight increase. The flexibility of the
panel is enhanced in
the case of thicker compliant layers, which is derivable from a mobility and
comfort
perspective. Use of thicker compliant layers also increases the thickness of
the global panel
system. This thickness increase by itself does not generally limit mobility or
restrict motion
since flexibility is actually enhanced. This increased thickness does
significantly increase the
effective section modulus of the global panel system during the transient
rigid state under
impact, which can significantly increase the "effective stiffness" of the
rigid panel.
[0051] With
reference now to FIG. 6, a single 1" thick monolithic panel is broken
up into 4 sub-laminates with viscoelastic layers there between, bringing total
thickness of the
new panel constructed from sub-laminates to 1.5." In this case, the Section
Moduli (SM) of
the 1" monolithic plate, and that of the 1.5" thick sub-laminate plate, are
determined by the
formulas:
Section Modulus = (1)2/6 for monolithic
Section Modulus = (1.5)2/6 for sub-laminate plate
SM 1 mono = 1/6
SM 1 sub = 2.25/6
[0052] The demonstration summarized in FIG. 6 and calculated hereinabove show
that the effective stiffness of the rigid sub-laminate panel under impact has
2.25 times the
stiffness and resistance to deformation as the monolithic plate. Thus, with
only a 50%
increase in thickness, 2.25 times the stiffness and resistance to deformation
is achievable.
[0053] The
"rigidized" compliance layer can act as a core material under impact to
improve the structural properties of panel system globally. The viscoelastic
layers can also be
engineered to provide some progression of load transfer into the individual
sub-laminates as
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the impact event progresses through the panel system, which can improve load
spread, energy
management and contribute to enhanced anti-penetration.
[0054]
Additionally, engineered viscoelastic dilation layers in accordance with the
present disclosure provide improved anti-ballistic properties, and improved
flexibility for
better mobility and increased range of motion without adding excessive weight
and/or bulk.
This rigidizing or "freezing" behavior under impact load can provide and one
or combination
of benefits, including: (1) distributing the impact loads, to spread them
within the assembly
reducing maximum peak loads and associated injury; (2) restricting deformation
of the panel
in the out-of-plane direction, thus reducing "back wall deformation" that is a
measure of how
much the panel is deflected inward towards the body of the wearer; (3)
increasing the area of
the panel used to resist the impact for better energy absorption and shock
dissipation; and, (4)
allowing improved resistance to projectile penetration by optimizing the
progressive response
of the panel system to the projectile as it strikes and enters the panel.
[0055] In
various embodiments, the sub-laminas can comprise hybridization of
fiber types. For example, hybridization can be inter-laminar (e.g. different
ballistic fiber
types, layer by layer). As illustrated in FIG. 7, hybridization of fiber types
can be intra-
laminar hybridization (e.g. one or more different fiber types within a single
layer, laid out in
accordance to a predetermined pattern or design). As illustrated in FIG. 8,
hybridization of
fiber types can comprise a comingling of fibers, (e.g. two or more fiber types
generally mixed
uniformly at the monofilament level).
[0056] The
system can alternatively comprise hybridization via different fiber
types (e.g., DyneemaTM and Kevlar). In various embodiments, the system can
comprise
hybridization via different styles, alternately different product forms,
alternately different
mechanical properties of the same or similar fiber or monofilament (i.e.
Dyneema SK 76
hybridized with Dyneema SK90, or Zylon HM hybridized with lower modulus
Zylon). This
approach can be useful when significant improvements in one fiber type are
offset by
reduction in another critical property.
[0057] For example, some DyneemaTM fibers have been drawn to a very fine
filament which improves in-plane response but introduces some other
limitations which
prevent full realization of the fibers anti-ballistic potential. Larger
diameter UHMWPE fibers
may have lower properties but their thicker filaments combined with a slightly
different
microstructure can combine to provide higher overall anti-ballistic
performance and
protection than either one is capable of independently. The system may feature
improvement
or optimization of the ballistic performance of the monofilaments, such as by
use of fiber
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surface treatments, surface functionalization, surface coatings, surface
grafting and/or
deposition with one or more types or layers to optimize the response and
integration of the
monofilaments to the matrix.
[0058] In
various embodiments, the system can further comprise engineered fiber,
such as matrix interfacial properties by use of fiber surface treatments,
surface
functionalization, surface coatings, surface grafting and/or deposition with
one or more types
or layers to optimize the response and integration of the monofilaments to the
matrix.
[0059] In various embodiments, the system can further comprise incorporation
of
various rate sensitive polymers and/or non-woven composites of various fibers
and polymers,
such as to produce a rate sensitive system, such as in strategic inter-laminar
and intra-laminar
locations for matrix and intra-laminar interfaces.
[0060] In various embodiments, the system can further comprise engineered
micro
flaws in monofilaments, such as to promote optimized localized massive
simultaneous micro-
fracture of filaments, such as to take advantage of the inherent high strain
energy release rate
thresholds related to the high Work-Energy-To-Initiate-Fracture properties
combined with the
high internal hysteresis associated energy dissipation with post failure
relaxation with some
anti-ballistic monofilaments such as UHMWPE and M5 fibers.
[0061] In various embodiments, sub-laminates may be made from a single anti-
ballistic monofilament, or multiple fibers may be combined to create a hybrid
of many types
of monofilaments.
[0062]
Hybridization may be at the global panel level where sub-laminates are
individually manufactured from one type of monofilament but several sub-
laminates
consisting of different types of monofilament may be used in a desired
configuration. At least
one non-hybrid sub-laminate (i.e. UHMWPE, Aramid, PBO, glass) along with sub-
laminates
featuring various forms and/or combinations of fiber classes or hybridization
schemes may be
used in a configuration.
[0063] All of the sub-laminates in a panel may be made from one single class
of
fiber such as UHMWPE, Aramid, PBO, Glass, etc. if desired. Panels made this
way can be
either flat or curved to better fit the wearer. If the panels are curved, the
sub-laminates may
be formed such that they nest together properly when stacked to form the total
laminate plate
system.
[0064] In
various embodiments, curved sections can be press formed, autoclave
formed, and/or laminate formed. Additionally, the curved sections can be
fabricated in one
set of sub-laminates, or fabricated individually and then assembled.
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[0065] In
various embodiments, under appropriate circumstances, considering such
issues as use environment, future technologies, cost, etc., other uses of the
composite system,
such as, for example, rigid plates made from same materials systems where
flexibility is not
desired, blast protection, containment of explosive failure of rotating
machinery, containment
of jet engine and other gas turbine engine compressor blade failures, sporting
good
protection, crash protection, reinforcement of masonry, brick and concrete
structure and
buildings to protect them from blast or seismic damages and secondary collapse
or failure,
vehicle, aircraft armor, use as a flexible "cloth" replacement for
conventional ballistic soft
vests, etc., may suffice.
[0066] The flexible sub-laminate can make a very high performance option as a
replacement for current vest fabrics for flexible vests and body armor. In
various
embodiments, the composite sub-laminates have superior anti-ballistic
properties, and load
spreading relative to conventional cloth technologies and having the further
advantage that
they do not absorb moisture and become liquid saturated, and the fiber
monofilaments are
fully encapsulated and protected so they are protected from abrasion,
chaffing, flex fatigue
and environmental degradation due to sweat, fluids, chemicals, and UV or
visible radiation.
[0067] In
vest applications it is generally advantageous to select the sub-laminate
thickness that gives the highest degree of anti-ballistic protection with the
thinnest overall
laminate thickness, and the maximum number of the thinnest unitapes, such as
oriented in as
many angular directions as is possible consistent with cost and production
throughput
constraints. Further, the use of shear thickening matrix and interlaminate
layers can be used
to improve impact properties.
[0068] A
thin, compliant, rate-sensitive layer or layers, about 1-10000 microns in
thickness, can be incorporated into the sub-laminate. In various embodiments,
this layer may
be about 1-100 microns in thickness. In various other embodiments, this layer
may be about
1-10 microns in thickness. This layer or layers can be a viscoelastic material
with high loss
factor for absorbing, damping, and dissipating impact forces and energy
release from the
impact while also adding flexibility to the sub-laminate. Strategically
locating interlayers can
substantially enhance load spread and energy management by tailoring the
impact impulse as
was previously discussed, and as illustrated graphically in FIG. 9.
[0069]
Antiballistic composite in accordance with the present disclosure is useful
for many aircraft applications since it can be desirable to have a semi-
flexible material, for
example, in the nacelle armoring the compressor blades of the engine. The
flexibility of the
armor prevents over-stiffening the nacelle, which could promote premature
fatigue of the
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engine support structure, but has enough rigidity during the impact of the
failed compressor
blades that it can retain structural integrity while simultaneously containing
the blade
fragments.
[0070]
Antiballistic composite in accordance with the present disclosure is also an
ideal solution for reinforcement of masonry brick, concrete structure and
buildings to protect
them from blast or seismic damages, and secondary collapse or failure by
laminating one or
more sub-laminate sheets to the walls or ceilings of the structures using an
integrated gel
style curing adhesive layer or via a sprayed or brushed on toughened adhesive
or a
combination of both types of bonding agents.
[0071] Antiballistic
composite in accordance with the present disclosure can be
transparent, opaque, translucent, colored, printed or textured for decorative
architectural
effects or to add camouflage, IR control or other Low Observable finishes and
textures.
Additionally, the material can incorporate a weatherable outer surface layer
that has an
environmental control function such as solar reflectivity or UV blocking for
insulation or
energy efficiency as a secondary feature.
[0072] It
will be apparent to those skilled in the art that various modifications and
variations can be made in the present disclosure without departing from the
spirit or scope of
the disclosure. Thus, it is intended that the present disclosure cover the
modifications and
variations of this disclosure provided they come within the scope of the
appended claims and
their equivalents.
[0073]
Likewise, numerous characteristics and advantages have been set forth in
the preceding description, including various alternatives together with
details of the structure
and function of the devices and/or methods. The disclosure is intended as
illustrative only and
as such is not intended to be exhaustive. It will be evident to those skilled
in the art that
various modifications may be made, especially in matters of structure,
materials, elements,
components, shape, size and arrangement of parts including combinations within
the
principles of the disclosure, to the full extent indicated by the broad,
general meaning of the
terms in which the appended claims are expressed. To the extent that these
various
modifications do not depart from the spirit and scope of the appended claims,
they are
intended to be encompassed therein
