Note: Descriptions are shown in the official language in which they were submitted.
CA 02789604 2012-09-12
ENERGY-DISSIPATING ARTICLES, MATERIALS AND FIBERS
This application claims priority on US Provisional Patent Application No.
61/535,041
filed September 14, 2011, incorporated herein by reference.
BACKGROUND OF THE INVENTION
[001] Fibers and structures formed therefrom have proven to be acceptable for
various
applications. Such fibers and structures formed therefrom are nevertheless
susceptible to
improvements that may enhance the overall performance of the fiber and
structure formed
therefrom. Therefore, a need exists in the art for improved fibers and
structures formed
therefrom that advance the art.
SUMMARY OF THE INVENTION
[002] In one aspect, a fiber includes at least a first portion extending
axially and including a
shear thickening fluid. The fiber further includes at least a second portion
radially outward from
the first portion. The second portion extends axially and radially encompasses
the first portion
over a length thereof. The shear thickening fluid may, for example, include
particles suspended
in a liquid phase. In a number of embodiments, the particles include at least
one of an oxide,
calcium carbonate or a polymer. For example, the particles may be Si02.
[003] In a number of embodiments, the second portion includes at least one
polymer. The at
least one polymer of the second portion may, for example, be processible from
a melt phase. In a
number of embodiments, the at least one polymer of the second portion is a
nylon, a
polyester, a polypropylene, or a polyethylene.
[004] The second portion may, for example, include an abrasion resistant
material. In a number
of embodiments, the abrasion resistant material is an abrasion resistant
polymer. The fiber may
further include a third portion extending axially and positioned radially
inward of the first
portion. The third portion may, for example, include a material having a
higher strength than the
second portion. The third portion may, for example, include at least one of a
high- strength
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polymeric material or a metallic material.
[005] In another aspect, a material includes a plurality of fibers. As
described above, each of
the plurality of fibers includes at least a first portion extending axially
and including a shear
thickening fluid. Each of the plurality of fibers further includes at least a
second portion radially
outward from the first portion. The second portion extends axially and
radially encompasses the
first portion over a length thereof.
[006] In a further aspect, a fabric includes a plurality of fibers. As
described above, each of the
plurality of fibers includes at least a first portion extending axially and
including a shear
thickening fluid. Each of the plurality of fibers further includes at least a
second portion radially
outward from the first portion. The second portion extends axially and
radially encompasses the
first portion over a length thereof. The plurality of fibers may, for example,
be woven into the
fabric. The plurality of fibers may also be nonwoven. The plurality of fibers
may, for example,
be arranged in a unidirectional manner or in a random manner.
[007] In still a further aspect, a ballistic panel includes at least one layer
of a material
including a plurality of fibers. As described above, each of the plurality of
fibers includes at
least a first portion extending axially and including a shear thickening
fluid. Each of the
plurality of fibers further includes at least a second portion radially
outward from the first
portion. The second portion extends axially and radially encompasses the first
portion over a
length thereof.
[008] The present invention, along with the attributes and attendant
advantages thereof, will
best be appreciated and understood in view of the following detailed
description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[009] Figure 1 A illustrates a cross-sectional view of an embodiment of a
fiber of the
subassembly of Figure 1 B along line 1 A-1 A thereof including a polymeric
sheath or outer
portion enclosing a core or inner portion of a shear thickening fluid.
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[0010] Figure 1 B illustrates a perspective view of a plurality of fibers
hereof oriented
generally parallel to each other, wherein the fiber ends are cut to expose the
inner core.
[0011 ] Figure 1 C illustrates a cross-sectional view of another embodiment of
a fiber of the
subassembly of Figure 1 D along line 1 C- I C thereof including a first
portion of a shear
thickening fluid encompassed by a second portion of a polymeric material and a
third portion
radially inward of the first portion.
[0012] Figure 1 D illustrates a perspective view of a plurality of fibers
hereof oriented
generally parallel to each other, wherein the fiber ends are cut to expose the
inner core.
[0013] Figure 2 illustrates a top plan view of the front of an embodiment of
an article of body
armor including a fabric as illustrated in Figures I A and 1 B, wherein a
front ballistic panel
assembly interior to a vest carrier is shown in dashed lines.
[0014] Figure 3 illustrates a top plan view of the rear of the article of body
armor of Figure 2,
wherein the rear closure sections of the opposing closure mechanisms are
folded back,
wherein a rear ballistic panel assembly interior to the vest carrier is shown
in dashed lines.
[0015] Figure 4A illustrates a top plan view of an embodiment of a subassembly
for use in
forming a front ballistic panel assembly of the article of body armor of
Figure 2.
[0016] Figure 4B illustrates a top plan view of an embodiment of a subassembly
for use in
forming a rear ballistic panel assembly of the article of body armor of Figure
2.
[0017] Figure 4C illustrates a cross-sectional view of the subassembly of
Figure 4A along
line A-A thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0018] As used herein and in the appended claims, the singular forms "a,"
"an", and "the"
include plural references unless the content clearly dictates otherwise. Thus,
for example,
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reference to "a fiber" includes a plurality of such fibers and equivalents
thereof known to
those skilled in the art, and so forth, and reference to "the fiber" is a
reference to one or more
such fibers and equivalents thereof known to those skilled in the art, and so
forth.
[0019] In a number of embodiments of fibers hereof, a fiber 1 includes at
least a first portion
or layer 2 of a shear thickening fluid as illustrated in Figures 1 A and 1 B.
First portion or layer 2
extends axially through at least a portion of fiber 1 and typically through
the entire fiber. Fiber
1 further includes at least a second axially extending portion or layer 4 (for
example, formed
from a polymeric material) which is positioned radially outward of first
portion 2 and
radially encompasses first portion 2 to retain the shear thickening fluid
within fiber 1 in the
manner of, for example, a sheath.
[0020] In a number of embodiments, a sheath (second portion 4) and core (first
portion 2) fiber
is extruded wherein the sheath of second layer 4 is formed from one or more
polymers such as
nylon 6, nylon 6,6 polyester, polypropylene, polyethylene (for example, an
ultra-high-
molecular-weight polyethylene such as DYNEEMA(X, available from DSM, of
Heelen,
Netherlands) SPECTRA available from Honeywell, Inc.) and/or other polymers
and the core of
the fiber is a dilatant or shear thickening fluid (STF). In a number of
embodiments, the polymer
or polymers of second portion 4 are processed/extruded from a melt phase.
[0021 ] Fibers hereof can include other portions or layers. For example,
multiple layers of shear
thickening fluids encompassed by, for example, polymer layers in a generally
alternating
concentric fashion. Figure 1 C illustrates another embodiment of a fiber 1 a
including at least a
first axially extending portion or layer 2a includes a shear thickening fluid.
As with fiber 1,
fiber 1 a further includes at least a second axially extending portion or
layer 4a (for example,
formed from a polymeric material) which is positioned radially outward of
first portion 2a and
radially encompasses first portion 2a to retain the shear thickening fluid
within fiber I a. In the
embodiment illustrated in Figure 1 C, fiber I a further includes a third
axially extending
portion 8a encompassed by second portion 4a. Second portion 4a may, for
example, be formed
from an abrasion resistant material such as an abrasion resistant polymer. In
a number of
embodiments, abrasion resistant materials used herein have, for example, an
abrasion value of at
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least 1000 cycles, at least 1500 cycles or at least 1900 cycles when tested
according to ASTM
3884. Third portion 8a may, for example, be formed from a high strength
material (for example,
a high strength polymer such as DYNEEMA or SPECTRA) or of a conductive
metallic material.
In a number of embodiments, high materials used herein have, for example, a
tensile strength of
at least 0.25 gigapascals, (GPa), at least 0.75 GPa, at least 1.5 GPa or at
least 2.25 GPa.
[0022] STF suitable for use herein can, for example, be formed as particles
suspended in a
liquid phase/solvent (for example, an organic solvent or an aqueous solvent).
The particles used
can be made of various materials, including, but not limited to, Si02 (silica)
or other oxides, Si02
or other oxides with a polymer (for example, polyethylene glycol), calcium
carbonate, or
polymers, such as polystyrene, polymethylmethacrylate, polyisobutenes (for
example,
OPPANOL , available from BASF Aktiengesellschaft of Ludwigshafen, Germany), or
other
polymers from emulsion polymerization. The particles can be stabilized in
solution or dispersed
by charge, Brownian motion, adsorbed surfactants, and adsorbed or grafted
polymers,
polyelectrolytes, polyampholytes, or oligomers. Particle shapes include
spherical particles,
elliptical particles, or disk-like or clay particles. The particles may be
synthetic and/or naturally
occurring minerals. Also, the particles can be either monodisperse,
bidisperse, or polydisperse in
size and shape. In a number of embodiments, particles having a particle size
less than, for
example, 100 microns may be used in forming STFs for use herein.
[0023] The solvents or liquid phases used to form the STFs can, for example,
be aqueous in
nature (i.e. water with or without added salts, such as sodium chloride, and
buffers to control pH)
for electrostatically stabilized or polymer stabilized particles, or organic
(such as ethylene glycol,
polyethylene glycol, ethanol etc.), or silicon based (such as silicon oils,
phenyltrimethicone). The liquid phase can also be composed of compatible
mixtures of liquids,
and may, for example, include free surfactants, polymers, and oligomers. The
liquids should be
environmentally stable so that they remain integral to the fabric and
suspended particles during
service.
[0024] The particles are suspended in the liquid to produce a fluid that has
shear thickening
properties. Shear thickening does not require a dilatant response, that is, it
may not be associated
CA 02789604 2012-09-12
with an increase in volume such as often observed in dry powders or sometimes
in suspensions
of larger particles (greater than 100 microns).
[0025] The fibers, yarns, fabrics (for example, woven fabrics or nonwoven
fabrics), materials
and/or articles hereof provide a number of advantages over fibers coated or
impregnated with a
dilatant or an STF. For example, the STF is contained in fluid form in the
core of the fibers
hereof. STF applied in a secondary operation such as coating or impregnation
is not contained.
By containing the STF in the fibers hereof, the STF is much more robust and
stable and less
likely to evaporate and/or degrade under higher temperature conditions (for
example, at ambient
summer temperatures or higher temperatures). Containing the STF in the fiber
also provides
more uniformity and consistency of the STF than current methods which involve
application
processes such as coating and/or impregnating. Coating and impregnation
methods are, for
example, susceptible to variations in thickness and coverage uniformity.
Containing the STF in
the fiber will also improve the overall durability of the STF, including its
abrasion resistance, as
compared to STFs applied to fibers in a secondary operation. Energy
dissipation may, however,
be further improved via coating or impregnating the exterior of fabrics hereof
with an STF to
enhance inter-fiber friction.
[0026] Fabrics formed from fibers hereof can, for example, be used to mitigate
blunt force
trauma in a ballistic vest when impacted by a projectile (bullet, spike,
blade, etc). Fibers hereof
can also be used to mitigate impact damage in other applications (for example,
in hardhats, in
advanced combat helmets (ACH), in shielding for machinery etc.).
[0027] Figure 2 illustrates a representative embodiment of an article of body
armor 10 in which
a body armor carrier is in the form of a vest 20. Vest 20 can be used alone or
in operative
connection with a connected garment such as a shirt (not shown). For example,
an exterior shell
fabric of the body armor can be sewn to the shirt. A user of body armor 10
first dons body armor
and then adjusts the fit of body armor vest 20 using one or more side closure
mechanisms.
Lightweight outer carriers in the form of vests similar to vest 20 are
available from Mine Safety
Appliances Company (MSA) of Pittsburgh, Pennsylvania under the mark PARACLETE
. Vest
is provided as a representative example of use of a fabric of fibers hereof in
a ballistic panel.
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One skilled in the art appreciates that the fibers hereof are suitable for use
in many different uses.
[0028] As described above, body armor 10 includes ballistic panel assemblies
or ballistic
resistant panel assemblies that provide resistance to, for example, edged
weapons, sharp objects,
and ballistic threats. As illustrated with dashed lines in, for example,
Figure 2, vest 20 includes a
generally contiguous (in coverage), flexible front ballistic panel assembly
200. Ballistic panel
assembly 200 can be formed as one, integral section or assembly or as a
plurality of separate
sections or assemblies. However, the coverage provided by ballistic panel
assembly 200 is
preferably contiguous. Front ballistic panel assembly 200 includes side
sections 21 Oa and 21 Ob
adapted to extend around the side of a user. Ballistic panel assembly 200,
including side sections
21 Oa and 21 Ob, is enclosed within an outer shell of fabric forming the front
of carrier or vest 20.
As illustrated with dashed lines in, for example, Figure 3, vest 20 also
includes a generally
contiguous (in coverage), flexible rear ballistic panel assembly 300. Like
front ballistic panel
assembly 200, rear ballistic panel assembly 300 can be formed as one section
or assembly or as a
plurality of separate sections or assemblies. Rear ballistic panel assembly
300 includes side
sections 31 Oa and 31 Ob adapted to extend around the side of a user. Like
ballistic panel
assembly 200, ballistic panel assembly 300, including side sections 31 Oa and
31 Ob, is enclosed
within an outer shell of fabric forming the rear of carrier or vest 20.
[0029] Figures 4A through 4C illustrate one embodiment of a ballistic panel
assembly or
ballistic package of the present invention Figure 4A illustrates a flexible
subassembly 230 for
use in forming front ballistic panel assembly 200, while Figure 4B illustrates
a flexible
subassembly 330 for use in forming rear ballistic panel assembly 300.
Subassemblies 230 and
330 can, for example, be designed for Type II level of ballistic performance
as set forth in
Section 2.2 of NIJ Standard-0101.06. Performance standards for ballistic
panels are, for
example, set forth in National Institute of Justice (NIJ) Standard-0101.06,
"Ballistic Resistance
of Body Armor". NIJ Standard-0101.06 is a technical document that specifies
the minimum
performance requirements that equipment must meet to satisfy the requirements
of criminal
justice agencies and the methods that shall be used to test this performance.
This standard is
used to determine which body armor models meet the minimum performance
requirements for
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inclusion on the NIJ Compliant Products List.
[0030] In the embodiment of Figures 4A through 4B, each of front ballistic
panel assembly 200
and rear ballistic panel assembly 300 can, for example, be manufactured using
generally the
same materials and procedures and differ generally only in shape. Figure 4C
illustrates a cross-
sectional view of subassembly 230 along line A-A of Figure 4A. A cross-section
of
subassembly 330 along line A-A of Figure 4B (which is not shown) is identical
to that of
subassembly 230.
[0031] As illustrated in Figure 4C, subassembly 230 (as well as subassembly
330) includes, for
example, a multi-ply (for example, a 2-ply) layer 232 of an aramid fabric on
the front, outer or
strike face thereof. The term "aramid" is short for aromatic polyamide. In one
embodiment,
layer 232 included two plies of GOLD FLEX material available from Honeywell.
No
adhesive was placed between the plies of GOLD FLEX material. Without
limitation to any
particular mechanism of operation, layer 232 is believed to operate, at least
in part, to alter the
shape, deform or flatten a projectile or bullet impacting layer 232 so that it
has less potential to
penetrate any adjacent layer(s).
[0032] Adjacent to layer 232 is a layer 234 including, for example, a
plurality of plies of, for
example, an aramid fabric. In one embodiment, layer 234 included, for example,
multiple plies
of TWARON woven fabric available from Teijin Aramid BV of Arnhem, The
Netherlands.
TWARON material is a very strong, light para-aramid (poly-paraphenylene
terephthalamide),
which has a high tensile strength and is thermally stable. TWARON fabrics also
exhibit high
impact and chemical resistance. No adhesive was used between the plies of
TWARON fabric in
layer 234. Without limitation to any particular mechanism of operation, it is
believed that the
projectile or bullet is stopped within layer 234 as a result, at least in
part, of elongation and
breakage of the high tensile strength fibers of the TWARON fabric.
[0033] Adjacent to layer 234 is a layer 236 including, for example, a fabric
formed from fibers 1
that forms the back, inner or wear face of subassembly 230. Layer 236 can, for
example,
be a single-ply layer or a multi-ply layer of such a fabric material with no
adhesive between the
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plies thereof. The diameter and/or other parameter of the fibers can be varied
or optimized to
achieve desired results via application of established engineering principles.
Layer 236 can
operate, at least in part, to limit deformation of the wear face of
subassembly 230 upon a ballistic
strike thereto to limit the amount of blunt force trauma experienced by a user
of vest 20. In that
regard (and, once again, without limitation to any particular mechanism of
operation,), layer 236
can, for example, operate to distribute rearward propagating force from the
projectile or bullet
over the surface area thereof and assists in limiting backface deformation or
backface signature
(BFS) as defined in Section 3.8 of NIJ Standard-0101.06. In that regard, the
allowable BFS is
the greatest extent of indentation in a backing material caused by a
nonperforating impact on
tested armor. As set forth in Section 3.9 of NIJ Standard-0101.06, the backing
material is a
homogeneous block of nonhardening, oil-based modeling clay placed in contact
with the back of
the armor panel during ballistic testing.
[0034] The foregoing description and accompanying drawings set forth the
preferred
embodiments of the invention at the present time. Various modifications,
additions and
alternative designs will, of course, become apparent to those skilled in the
art in light of the
foregoing teachings without departing from the scope of the invention. The
scope of the
invention is indicated by the following claims rather than by the foregoing
description. All
changes and variations that fall within the meaning and range of equivalency
of the claims are to
be embraced within their scope.
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