U.S. patent application number 12/005890 was filed with the patent office on 2010-11-04 for fabric architectures for improved ballistic impact performance.
Invention is credited to Ronald G. Egres, JR..
Application Number | 20100275764 12/005890 |
Document ID | / |
Family ID | 40756929 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100275764 |
Kind Code |
A1 |
Egres, JR.; Ronald G. |
November 4, 2010 |
Fabric architectures for improved ballistic impact performance
Abstract
A woven fabric from yarn for use in the manufacture of ballistic
projectile or puncture resistant articles where the fabric has a
first plurality of parallel oriented yarns within the plane of the
fabric interwoven with a second plurality of parallel oriented
yarns within the plane of the fabric having a direction/orientation
within the plane of the fabric different from that of the first
plurality and where the crossing of any fiber yarn from the first
plurality with a fiber yarn from the second plurality forms a pair
of acute vertical angles having an angular measurement less than 90
degrees.
Inventors: |
Egres, JR.; Ronald G.;
(Milothian, VA) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1122B, 4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
40756929 |
Appl. No.: |
12/005890 |
Filed: |
December 28, 2007 |
Current U.S.
Class: |
89/36.02 ;
442/203; 89/914 |
Current CPC
Class: |
D03D 15/267 20210101;
B32B 2307/558 20130101; D10B 2321/02 20130101; B32B 2262/0284
20130101; B32B 5/022 20130101; D10B 2101/06 20130101; B32B 2307/54
20130101; B32B 2307/718 20130101; B32B 2571/02 20130101; B32B
2307/50 20130101; Y10T 442/3179 20150401; B32B 5/024 20130101; D03D
13/002 20130101; B32B 2307/58 20130101; B32B 5/04 20130101; B32B
5/26 20130101; D10B 2201/24 20130101; D10B 2321/10 20130101; D10B
2501/04 20130101; D10B 2101/12 20130101; B32B 5/06 20130101; B32B
2262/105 20130101; D10B 2101/08 20130101; B32B 7/12 20130101; B32B
2262/101 20130101; B32B 2307/72 20130101; B32B 2262/02 20130101;
B32B 2262/0269 20130101; D10B 2321/06 20130101; B32B 2262/0253
20130101; D10B 2331/04 20130101; B32B 2262/14 20130101; D03D 15/00
20130101; B32B 5/12 20130101; B32B 27/12 20130101; B32B 2262/106
20130101; D03D 1/0052 20130101 |
Class at
Publication: |
89/36.02 ;
442/203; 89/914 |
International
Class: |
F41H 5/04 20060101
F41H005/04; D03D 13/00 20060101 D03D013/00 |
Claims
1. A fabric woven from yarn for use in the manufacture of ballistic
projectile resistant articles, said fabric, comprising a first
plurality of parallel oriented yarns within the plane of the
fabric, interwoven with a second plurality of parallel oriented
yarns within the plane of the fabric having a direction/orientation
within the plane of the fabric different from that of the first
plurality, where the crossing of any fiber yarn from the first
plurality with a fiber yarn from the second plurality forms a pair
of acute vertical angles having an angular measurement less than 90
degrees.
2. The fabric of claim 1, where the fabric is comprised of fiber
yarns containing aromatic polyamides including poly(p-phenylene
teraphthalamide), poly(metaphenylene isophthalamide),
p-phenylenebenzobisoxazole, polybenzoxazole, polybenzothiazole,
aromatic unsaturated polyesters such as polyethylene terephthalate,
aromatic polyimides, aromatic polyamideimides, aromatic
polyesteramideimides, aromatic polyetheramideimides and aromatic
polyesterimides or copolymers of any of the above mentioned classes
of materials.
3. The fabric of claim 1, where the fabric is comprised of fiber
yarns containing ultra high molecular weight polyethylene.
4. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 80 and 89 degrees.
5. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 70 and 80 degrees.
6. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 60 and 70 degrees.
7. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 50 and 60 degrees.
8. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 40 and 50 degrees.
9. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 30 and 40 degrees.
10. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 20 and 30 degrees.
11. The fabric of claim 1, where the angular measure of the acute
vertical angles is between 10 and 20 degrees.
12. The fabric of claim 1, where the angular measure of the acute
vertical angles is less than 10 degrees.
13. A multi-layer ballistic projectile or puncture resistant
article assembled from a plurality of substantially unattached
non-woven fabric layers, woven fabric layers, or composite fabric
plies in which at least one of the layers in the assembly is a
biaxial fabric made of fiber yarns having a first plurality of
parallel oriented yarns within the plane of the fabric, interwoven
with a second plurality of parallel oriented yarns within the plane
of the fabric having a direction/orientation within the plane of
the fabric different from that of the first plurality, where the
crossing of any fiber yarn from the first plurality with a fiber
yarn from the second plurality forms a pair of acute vertical
angles having an angular measurement less than 90 degrees.
14. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 80 and 89 degrees.
15. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 70 and 80 degrees.
16. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 60 and 70 degrees.
17. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 50 and 60 degrees.
18. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 40 and 50 degrees.
19. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 30 and 40 degrees.
20. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 20 and 30 degrees.
21. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
between 10 and 20 degrees.
22. The article of claim 13, where the angular measure of the acute
vertical angles of at least one of the biaxial fabric layers is
less than 10 degrees.
23. The article of claim 13, in which at least two of the biaxial
fabric layers are oriented such that the yarn orientations in one
layer are offset from the yarn orientations in a second layer.
24. The article of claim 13, in which at least two of the biaxial
fabric layers are oriented such that the yarn orientations in one
layer are the same as the yarn orientations in a second layer.
25. A composite fabric ply comprising at least one fabric woven
from yarn for use in the manufacture of ballistic projectile
resistant articles, said fabric, comprising a first plurality of
parallel oriented yarns within the plane of the fabric, interwoven
with a second plurality of parallel oriented yarns within the plane
of the fabric having a direction/orientation within the plane of
the fabric different from that of the first plurality, where the
crossing of any fiber yarn from the first plurality with a fiber
yarn from the second plurality forms a pair of acute vertical
angles having an angular measurement less than 90 degrees and one
other fabric layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to fabric architectures and
soft body armors constructed therefrom.
[0003] 2. Description of the Related Art
[0004] Protective body armors such as those providing protection
against ballistic and stab type threats have long been an area of
significant interest. One challenge for body armor manufacturers is
to provide adequate protection from a particular threat or threats
that the wearer may be subjected to in the field, while minimizing
the weight, or areal density of the protective garment so as not to
impede the dexterity of the wearer.
[0005] Characterization of the protective capabilities of any armor
material against ballistic projectile threats, such as deformable
bullets and non-deformable shrapnel, requires some determination of
the ballistic velocity limit with respect to the material's areal
density and size, as well as the properties of the projectile
(mass, hardness, shape, etc.). One common ballistic limit
performance criteria is the ballistic V50, or the velocity at which
50% of the projectiles can be defeated by the armor. Specific
testing and calculation protocols for determining V50 of body
armors are outlined by the National Institute of Justice (NIJ)
Standard-0101.04 Ballistic Resistance of Personal Body Armor, dated
September 2000. Beyond the ability of armor to stop the penetration
of a projectile, the need to minimize blunt trauma associated with
the ballistic impact for concealable body armors worn by police,
security, and correctional officers, becomes an additional safety
requirement set forth by NIJ Standard-0101.04. This standard
outlines the testing protocol and performance requirements for an
acceptable level of blunt trauma through measurement of the
backface signature associated with ballistic impact of armors
placed upon a clay witness simulation material. In NIJ
Standard-0101.04, the acceptable amount of backface deformation is
defined as being no greater than 44 mm in a clay witness (Roma
Plastilina clay, 5.5 in (140 mm) clay witness depth).
[0006] The NIJ Standard-0101.04 provides ballistic requirements
specific to different types of projectiles and impact energy
levels. Three common NIJ threat levels for soft body armor include
Threat Level II, IIA, and IIIA. Threat level II relates to higher
velocity 357 magnum, 10.2 g (158 gr) and 9 mm, 8.0 g (124 gr)
bullets (impact velocities of less than about 1400 ft/s (427 m/s)
and 1175 ft/s (358 m/s), respectively). Level IIA relates to lower
velocity 40 S&W caliber full metal jacket bullets, with a
nominal mass of 11.7 g (180 gr) and 9 mm 8.0 g (124 gr) bullets,
(impact velocities of less than about 1025 ft/s (312 m/s) and 1090
ft/s (332 m/s), respectively). Threat level IIIA relates to 44
magnum, 15.6 g (240 gr) and sub machine gun 9 mm (124 gr) bullets
having impact velocities of less than about 1400 ft/s).
[0007] While the ballistic performance requirements set forth above
can be achieved using any of several commercially available
anti-ballistic materials, or combinations of said materials, the
challenge for soft body armor manufactures is the selection and
arrangement of ballistic layers required to prevent penetration
with an acceptable safety margin and minimize backface deformation
while also minimizing the weight, bulk and stiffness of the armor
to improve comfort.
[0008] Commercially available anti-ballistic materials include a
variety of woven ballistic fiber yarn fabrics, ballistic fabric
reinforced composites, ballistic fiber unidirectional laminates and
nonwovens. Of these various constructions, woven fabrics fabricated
from high tenacity fiber yarns have the longest history of use in
soft body armor fabrication. Weaving has long been a relatively
inexpensive means of uniformly generating fabric ballistic
resistant plies from high tenacity fiber yarns, relying on
mechanical interlocking or "interlacing" of the yarns to hold the
yarns in place instead of chemical locking by adhesive resins which
can contribute additional weight and stiffness to a garment. Soft
body armors fabricated from ballistic resistant fabrics are very
often more conformable and flexible during use, providing greater
comfort than hybrid armors containing stiff backface control layers
such as unidirectional fiber laminates or resin impregnated
fabrics. Additionally, it has been shown that ballistic resistant
garments generated entirely of woven high tenacity fiber yarns
maintain ballistic resistant properties after years of service and
wear. Alternatives to an all woven ballistic resistant vest are in
commerce. Such articles are prepared from combinations of high
tenacity fibers, matrix resins and films, often making them more
costly to produce. Additionally, by virtue of the component
materials having temperature and strain dependent physical
properties (eg. coefficient of thermal expansion, modulus, etc.)
dissimilar to that of the ballistic fiber, these composite layers
often have a useable life cycle dictated by the weakest of the
materials selected.
[0009] Typical biaxial woven ballistic resistant fabrics (fabrics
consisting of interwoven interlaced yarns having two yarn
orientations within the plane of the fabric) are generated on
automated looms. These looming operations generate woven fabrics
having interwoven fill fiber yarns oriented 90 degrees to those
yarns in the warp, or machine direction. The fabric properties are
largely governed by four basic variables: yarn denier, thread
count, weave pattern and fabric finish. Several styles of woven
fabrics exist, including plain, satin, twill, basket, and leno
weaves. Meeting the minimum ballistic performance requirements
using only the above woven fabrics presents a challenge for
ballistic armor manufacturers. While many low cover factor (loosely
woven) ballistic resistant fiber yarn fabrics provide satisfactory
V50 performance at the desired areal density (vests fabricated
therefrom can be shown to repeatedly impede projectiles from
penetrating the vest material at velocities safely above the
threshold values outlined in NIJ Standard-0101.04), they do not
provide adequate backface deformation resistance. Conversely, the
use of higher cover factor (more tightly woven) ballistic resistant
fiber yarn fabrics at the same vest areal density while improving
backface deformation performance, often results in significant
reduction in V50 performance, sometimes falling below the NIJ
Standard-0101.04 velocities required for backface signature
measurement. Currently no all p-aramid fiber yarn (such as that
sold under the trade name Kevlar.RTM. or Twaron.RTM.) woven fabric
vests are available commercially at an areal density of less than 1
lb/ft.sup.2, that can meet the NIJ Standard-0101.04 level IIIA
backface requirement for a 44 magnum ballistic threat.
[0010] One common method for reducing the backface signature in
soft body armors is through incorporating rigid plies of high
tenacity fiber or fabric reinforced resin composite plies to impede
deformation during impact. This includes bonding polymeric films or
applying polymeric coatings to woven ballistic'fabrics, or bonding
two woven ballistic fabric layers using a low melting temperature
polymer film, or pressure sensitive adhesive to provide an
anti-ballistic ply that can be added to ballistic body armor
constructions to improve backface signature, as described in WO
00/08411, U.S. Pat. No. 5,677,029, and US 2003/0109188. Resin or
elastomer impregnated ballistic fiber fabric is another type of
composite ply added to ballistic vest constructions to improve
ballistic backface signature. While the addition of these layers
has been shown to improve the backface signature performance of an
armor material, they can often have a deleterious effect on V50
performance. In addition, the resin adds to the weight and
stiffness of the ballistic vest assembly.
[0011] Unidirectional fiber laminates, comprised of a first
plurality of oriented parallel high tenacity fibers in a polymeric
matrix adhesively bound to a second plurality of oriented parallel
high tenacity fibers in a polymeric matrix, where the fiber
orientation of the second plurality is often 90 degrees rotated
relative to the orientation of the first plurality, have become
popular anti-ballistic materials that can provide good backface
trauma control while maintaining safe V50 performance. Methods of
making these unidirectional fiber laminates are generally described
in U.S. Pat. Nos. 4,916,000; 4,748,064; 4,737,401; 4,681,792;
4,650,710; 4,623,574; 4,563,392; 4,543,286; 4,501,854; 4,457,985,
and 4,403,012. These unidirectional laminates are commercially
available under the trade names Spectra Shield.RTM. Plus Flex, and
Gold Flex.TM., from Honeywell International, Inc. and
Dyneema.RTM.UD from DSM. While these unidirectional fiber laminates
can be used alone to provide ballistic protection, it has been
shown that further reductions in areal density without performance
loss can be achieved when these materials are used in conjunction
with woven ballistic fiber yarn fabrics, as illustrated in U.S.
Pat. No. 6,119,575
[0012] Performance improvements associated with using
unidirectional fiber or fabric and resin composite layers in vests
can be very dependent on their location within the multi-ply
construction, as discussed in U.S. Pat. No. 6,119,575. In many
documented instances, the placement of these stiffer composite
layers behind traditional ballistic fabrics provides the optimum in
backface signature and V50 performance. Due to this "sidedness"
these hybrid ballistic vest constructions can be inadvertently worn
inside-out, or inserted the wrong way into a tactical vest,
providing less than optimal protection from projectile threats.
Hence there is value in monolithic (comprised of all the same plies
of anti-ballistic material) or front-back symmetric ballistic
resistant armor constructions.
[0013] The need exists for a lightweight, all woven fabric body
armor that can reduce the blunt trauma associated with ballistic
impact. Prior to the advent of the inventive biaxial (comprised of
interlaced fiber yarns having two distinct orientations within the
plane of the fabric) fabric architectures, and soft body armor
constructions described herein, no documented, all-woven, p-aramid
fabric ballistic body armors had existed having an areal density
less than about 1 lb/ft.sup.2 fulfilling the NIJ Standard-0101.04
backface requirement for a 44 caliber deformable projectile
(backface signature below 44 mm for projectile velocities of
1430.+-.30 ft/s (436.+-.9 m/s)).
SUMMARY OF THE INVENTION
[0014] In one embodiment, the invention is directed to a biaxial
fabric woven from yarn for use in the manufacture of ballistic
projectile or puncture resistant articles, said biaxial fabric,
comprising a first plurality of yarns oriented parallel within the
plane of the fabric, interwoven with a second plurality of parallel
oriented yarns within the plane of the fabric having a
direction/orientation within the plane of the fabric different from
that of the first plurality, where the crossing of any fiber yarn
from the first plurality with a fiber yarn from the second
plurality forms a pair of acute vertical angles having an angular
measurement less than 90 degrees.
[0015] In another embodiment, the invention is directed a
multi-layer ballistic projectile or puncture resistant article
assembled from a plurality of substantially unattached non-woven or
woven fabric layers comprising yarns selected, either alone or in
combination, from the group comprising aromatic polyamide,
polyolefin, polyareneazole, polyester, rayon, liquid crystal
polymer, fiberglass, carbon fiber, ceramic, polyacrylonitrile and
polyvinyl alcohol, in which at least one of the layers in the
assembly is a biaxial fabric comprising a first plurality of yarns
oriented parallel within the plane of the fabric, interwoven with a
second plurality of parallel-oriented yarns within the plane of the
fabric having a direction/orientation within the plane of the
fabric different from that of the first plurality, where the
crossing of any fiber yarn from the first plurality with a fiber
yarn from the second plurality forms a pair of acute vertical
angles having an angular measurement less than 90 degrees.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a prior art example of a woven fabric.
[0017] FIG. 2 is a magnified image of one embodiment of the
inventive ballistic resistant fabric construction.
[0018] FIG. 3A is an illustration of the preparation of
bias-oriented fabric strips from a roll of conventional woven
fabric
[0019] FIG. 3B shows the fabric cut from the roll shown in 3A
clamped in a trellising apparatus.
[0020] FIG. 3C shows the fabric clamped in the trellising apparatus
and extended.
DETAILED DESCRIPTION OF THE INVENTION
Glossary of Terms Used Herein
[0021] Acute angles--angles measuring less than 90 degrees.
[0022] Woven fabric--a fabric comprised of one plurality of fiber
yarns oriented in one direction, interwoven with a second plurality
of yarns oriented in a direction different from that of the first
plurality. The first plurality of parallel yarns aligned in the
machine direction are referred to as warp yarns. Those interwoven
yarns oriented 90 degrees to the warp are referred to as the fill
or weft yarns.
[0023] Bias woven or bias-oriented fabric--a two dimensional woven
or braided fabric that when oriented in the XY plane, where X is
the machine direction (length), and Y is the transverse direction
(width) of the fabric, contains interlaced yarns that are oriented
in a different direction from the X and Y axes within the plane of
the fabric.
[0024] Bias orientation--In a biaxial woven fabric comprised of a
plurality of yarns oriented in one direction within the plane of
the fabric, interwoven with a second plurality of yarns having an
orientation different from the first, the direction parallel to any
ray bisecting any angle formed between a fiber yarn from the first
plurality with that of a yarn from the second plurality.
[0025] Unidirectional fiber layer--a layer having fibers arranged
substantially parallel along a common fiber direction
[0026] Composite fabric ply--a combination of one woven fabric
layer and at least one second layer which could be another fabric
layer, a unidirectional fiber layer, a polymeric film, a polymeric
resin impregnated into the fabric structure, etc. The one woven
fabric layer can be united with the second layer through stitching,
melt adhesives, pressure sensitive adhesives, compression molding,
coating.etc.
[0027] Supplementary angle--Two angles are called supplementary
angles if the sum of their degree measurements equals 180 degrees.
One of the supplementary angles is said to be the supplement of the
other.
[0028] Vertical angles--For any two lines (rays) that cross, such
as in the diagram below, angle A and angle B are called vertical
angles. Vertical angles have the same degree measurement. Angle C
and angle D are also vertical angles.
##STR00001##
[0029] Trellis angle--in biaxial fabrics, the acute angle formed
between any two yarns having different orientation within the plane
of the fabric, observed in biaxial braided structures or achieved
by in-plane extension of biaxial woven structures in either bias
direction.
[0030] Trellis direction--a direction parallel with the line
bisecting acute vertical angles.
[0031] Cover Factor--the fraction of the surface area of the fabric
that is covered by yarns assuming a round yarn shape.
[0032] V50--V50 ballistic limit testing is a statistical test,
originally developed by the U.S. military to evaluate hard armor.
V50 testing experimentally identifies the velocity at which a
bullet has a 50 percent chance of penetrating the test object.
[0033] Backface signature (BFS)--The depth of the depression made
in the backing material, created by a non-penetrating projectile
impact. The backface signature is measured from the plane defined
by the front edge of the backing material fixture. In accordance
with the National Institute of Justice (NIJ) Standard-0101.04
Ballistic Resistance of Personal Body Armor, the value is not
allowed to exceed the limit of 44 mm.
[0034] The present invention is directed in various embodiments at
a new class of ballistic resistant fabric architectures, as well as
ballistic layers and multi-layer body armor constructions made
therefrom that exhibit improved ballistic backface deformation over
traditional woven ballistic fabrics. One embodiment of this
invention involves generating ballistic fabric architectures that
can impart significant backface signature improvements to body
armor that have never been achieved using traditional ballistic
fabrics. A second embodiment of this invention is the generation of
balanced ballistic layers from the ballistic fabric architecture
for use in body armor assembly. A third embodiment of this
invention is the fabrication of specific multilayer vest
constructions incorporating the inventive ballistic fabric
architectures.
[0035] The first embodiment of this invention can be described by
first referring to FIG. 1 that shows a prior art example of a woven
fabric 10. The figure shows a magnified example of a plain weave
construction comprised of multifilament yarns, where the
intersection of a first set of yarns 1 parallel in direction within
the plane of the fabric as indicated by line X is interwoven with a
second set of yarns 2 parallel within the plane of the fabric and
oriented 90 degrees from that of the first set as indicated by line
Y. Intersections of yarns from the first set with those in the
second set form angles A-D, each measuring 90 degrees. A line L is
shown as bisecting angles A and B.
[0036] The first embodiment of this invention is a woven fabric
architecture comprising a first plurality of parallel oriented
yarns within the plane of the fabric, interwoven with a second
plurality of parallel oriented yarns within the plane of the fabric
having a direction/orientation within the plane of the fabric
different from that of the first plurality, where the intersection
of any fiber yarn from the first plurality with a fiber yarn from
the second plurality forms a pair of acute vertical angles, having
an angular measurement less than 90 degrees and necessarily a pair
of obtuse vertical angles, supplementary to the aforementioned
acute angles, having a measurement greater than 90 degrees. This
inventive ballistic fabric arrangement 10' is shown in FIG. 2.
comprised of a first plurality of parallel yarns 1' oriented within
the plane of the fabric as indicated by line X', interwoven with a
second plurality of parallel yarns 2' within the plane of the
fabric as indicated by line Y' having orientation different from
the first plurality where the intersection of any fiber yarn from
the first plurality 1' with any fiber yarn from the second
plurality 2' forms a pair of vertical angles within the plane of
the fabric, where the angular measurements of the acute vertical
angles A' and B' are equal in value and less than 90.degree., and
the angular measurements of the obtuse vertical angles C' and D'
are equal in value and greater than 90.degree.. This inventive
fabric can be achieved by extending the original woven fabric in
the trellis direction as explained below by reference to FIGS.
3A-3C. For the purpose of this disclosure, we will refer to the
orientation, or trellis extension direction, of these fabrics as
the directions parallel to the line L' bisecting the acute vertical
yarn crossing angles A' and B' as illustrated in FIG. 2
[0037] The scope of this invention is not limited to a construction
consisting of yarns interlaced in a one over-one under every other
yarn alternating structure as illustrated in FIG. 2, analogous to
the interlacing for plain woven fabric illustrated in FIG. 1.
Rather, the scope of this invention includes, but is not limited to
architectures where yarns in one direction in the plane of the
fabric may alternatively pass over the top of, or beneath two or
more adjacent yarns oriented in the second direction in any
particular repeat pattern conceivable, including, for example
fabric architectures which can be constructed through
bias-direction extension of satin weaves (including but not limited
to 3-harness satin weaves, 4-harness satin weaves (crow's foot),
5-harness satin weaves, and 8-harness satin weaves, etc.), basket
weaves, and twill weave structures.
[0038] The fiber yarns used in constructing the ballistic resistant
architectures described in this disclosure, would have a tensile
strength greater than about 8 g/denier or more preferably greater
than about 12 g/denier. In an embodiment of this invention, the
fibers in the fabric yarn will be made of an aromatic polymeric
material. Aromatic polymers include aromatic polyamides such as
poly(para-phenylene teraphthalamide), sold under the trade names
Kevlar.RTM. available from E.I. du Pont de Nemours and Company,
Wilmington, Del. (DuPont) and Twaron.RTM. available from Teijin,
and poly(metaphenylene isophthalamide) sold under the trade name
Nomex.RTM., p-phenylene benzobisoxazole (PBO available from
Toyobo), polybenzoxazole, polybenzothiazole. Other aromatic
polymers include aromatic unsaturated polyesters such as
polyethylene terephthalate, liquid crystalline thermotropic
polyesters such as those sold under the trade name Vectran.RTM.
available from Kuraray, aromatic polyimides, aromatic
polyamideimides, aromatic polyesteramideimides, aromatic
polyetheramideimides and aromatic polyesterimides. Copolymers of
any of the above mentioned classes of materials can also be
used.
[0039] Other ballistic grade fiber yarns having tenacity greater
than 12 g/denier that could be used to fabricate these woven
architectures include polyolefins, most notably high molecular
weight polyethylene, sold under the trade names Dyneema.RTM.
available from DSM and Spectra.RTM. available from Honeywell
International, high molecular weight polypropylene and copolymers
thereof.
[0040] For the example cases presented in this disclosure,
bias-oriented fabric strips were obtained through cutting ballistic
fabrics from fabric rolls having warp fibers oriented in the
machine (longitudinal) direction, and fill fiber yarns oriented 90
degrees to that of the warp direction (transverse to the machine
direction, parallel to the axis of the fabric roll). These strips
were prepared through cutting along a bias direction, as
illustrated in FIG. 3A. The fabrics were then extended to form the
ballistic resistant bias fabric architecture once clamped into the
trellising apparatus illustrated in FIGS. 3B and 3C.
[0041] While the above method was adequate for generating the
examples herein, a process to economically generate these
structures would require the manufacture of bias-oriented fabric
extended to create the desired trellis angle having continuous
running lengths and enough width to provide for vests to be cut
therefrom. Methods of generating bias-oriented fabrics have been
disclosed in the patent literature. Examples include U.S. Pat. No.
6,494,235, U.S. Pat. No. 6,494,238, U.S. Pat. No. 4,907,323 and WO
99/55519. Bias-oriented woven structures can also be generated
using braiding processes known in the industry, to either directly
generate continuous fabric sheets, or tubular constructions that
can be slit along one side parallel to the axis of the tube to
produce a flat continuous sheet of bias-oriented fabric. A second
means of fabricating a continuous sheet of bias oriented fabric
would be to helically cut a tubular fabric generated from a tubular
loom, where warp fibers are oriented parallel to the axis of the
tube and fill fiber is oriented circumferentially, also described
in U.S. Pat. No. 4,299,878
[0042] A second embodiment of this invention is the generation of a
free-standing trellised fabric architecture, or trellised fabric
composite ply that can be used in the construction of a ballistic
body armor. Such a stabilized layer of the trellised ballistic
architecture could be provided as a continuous rolled good for use
by ballistic body armor manufacturers. It must be understood that
individual fabric layers having this inventive architecture with no
means of stabilization are inherently unbalanced due to their
anisotropic nature. That is, the fabric layers have the tendency to
readily revert (bounce back) to a more balanced structure (as
represented by an increase in acute angle measurement) with little
perturbation. This makes these fabric architectures difficult to
handle without unwanted reversion during body armor assembly. One
method used to maintain the trellised state in an individual fabric
layer is stitching through a sewing operation once the desired
trellis angle is achieved. Though stitching in any direction may
afford some stability to the ballistic fabric, most effective
stitching to impede the "bounce-back" tendency is stitching in a
direction perpendicular to that of the trellis direction. Stitching
in this fashion at regular intervals across a long piece of
bias-oriented fabric extended to the desired acute trellis angle
provides a stabilized single fabric sheet. Alternatively, a
polymeric layer (having an adequate degree of dimensional
stability/reversion resistance to oppose the tendency of the
trellis fabric "bounce-back") could be adhered to the trellised
fabric layer to help maintain the structure. Such a polymeric layer
could be in the form of a thin film that is melt-bonded to the
fabric (via heated platen compression or heated calendering) or a
polymer coating (solvent based or emulsion/latex) applied and then
dried to one or both sides of the fabric while held in the extended
state. Such polymeric layers could be continuous in that they cover
the entire surface of the fabric, or could be discontinuous across
the surface of the fabric architecture to minimize weight and
stiffness contribution to the ballistic layer. Discontinuous
coatings of resins include open patterns or lines of resin on the
fabric, or discrete spots. This can be achieved using melt adhesive
films cut into open patterns that can be welded to the fabric
surface. Alternatively, solvent based polymer coatings or polymer
emulsions/latexes can be transfer printed in the aforementioned
discontinuous fashion onto the trellised fabrics using gravure
printing processes or the like.
[0043] The individual inventive trellised fabric layers and/or
composite plies described above can be used to construct the entire
ballistic body armor, or could be used in conjunction with other
anti-ballistic materials in a ballistic body armor. The sewn or
adhered polymer film or coating stabilized structures could be
stacked in various arrangements within the body armor.
[0044] Balanced composite fabric plies can also be generated by the
union of two of the trellised fabric architectures, assembled in
such a way to have the acute angle or trellis direction of one
fabric (defined as being parallel to the line bisecting the acute
vertical angles formed by two interwoven yarns) oriented at a 90
degree angle with respect to the acute angle direction of the
second trellised fabric architecture. The resulting two layers of
fabric could be bound together through stitching with a sewing
operation, adhesive bound using a pressure sensitive adhesive,
adhered together through melt adhesion by placing a polymeric or
thermoplastic elastomer films between the layers, compressing the
layers together in a press or via a calendaring operation while
heating above the melting point to promote adhesion. Thermosetting
resins or elastomers could also be used to unite the two layers of
materials together. As with the polymer coating stabilized single
fabric layer architectures, discontinuous coatings are most
preferred as a means of reducing stiffness and weight of these two
fabric sandwich structure laminates.
EXAMPLES
Comparative Example 1
[0045] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 25 layers of style 726 greige fabric
available from JPS Industries Inc, Anderson, S.C. This is a plain
weave fabric made from 840 denier Kevlar.RTM. 129 fiber yarns,
having a yarn count of 26 ends per inch warp and 26 ends per inch
fill, measured extracted yarn tenacities of 27 g/denier warp and 26
g/denier fill, and an areal density of 6.04 oz/yd.sup.2 (205
g/m.sup.2). Individual square fabric layers were generated by
cutting along the warp and fill direction (having warp and fill
fiber yarns parallel to the sides of the square). Fabric layers
were arranged with warp and fill fibers oriented in the same
direction for all fabric layers in the stack. The fabric layers
were stitched together about the perimeter of the panel 1/2 in
(1.27 cm) from the edge. A 2 in.times.2 in (5.1.times.5.1 cm) quilt
pattern was also sewn through the thickness of the panel to
mechanically bind the layers together. Ballistic backface signature
impact testing was performed using 44 magnum bullets at velocities
of 1430.+-.30 ft/s on targets placed against a clay witness (Roma
plastilina clay) following the protocol outlined by NIJ Standard
0101-04. The ballistic V50 for 44 magnum bullets was determined for
this test panel. The backface signature and V50 results for 44
Magnum bullet ballistic testing at 1430.+-.30 ft/s against a clay
witness appear in Table 1.
Comparative Example 2
[0046] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 36 layers of a plain weave fabric made from
840 denier Kevlar.RTM. 129 fiber yarns by JPS Industries Inc.,
having a yarn count of 18 ends per inch warp and 18 ends per inch
fill, measured extracted yarn tenacities of 27 g/denier warp and 26
g/denier fill, and an areal density of 4.04 oz/yd.sup.2 (137
g/m.sup.2). Individual fabric layers were cut from the fabric roll
having warp and fill yarns parallel to the sides of the square.
Fabric layers were arranged with warp and fill fiber yarns oriented
in the same direction for all fabric layers in the stack. The
fabric layers were stitched together about the perimeter of the
panel 1/2 in (1.27 cm) from the edge. A 2 in.times.2 in
(5.1.times.5.1 cm) quilt pattern was also sewn through the
thickness of the panel to mechanically bind the layers together.
The backface signature and V50 results for 44 Magnum bullet
ballistic testing at 1430.+-.30 ft/s against a clay witness appear
in Table 1.
Comparative Example 3
[0047] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 37 layers of style 726 greige fabric having
the properties described in Comparative Example 1. The target was
fabricated having an alternating fabric orientation for every other
layer with 19 fabric squares having the sides of the square
oriented parallel with the warp and fill fiber yarn directions
(0-90), and 18 layers oriented 45 degrees rotated from that of the
previous fabric (-45, +45). The fabric layers were stitched
together about the perimeter of the panel 1/2 in (1.27 cm) from the
edge. A 2 in.times.2 in (5.1.times.5.1 cm) quilt pattern was also
sewn through the thickness of the panel to mechanically bind the
layers together. The backface signature and V50 results for 44
Magnum bullet ballistic testing at 1430.+-.30 ft/s against a clay
witness appear in Table 1.
Comparative Example 4
[0048] A 15 in.times.15 in (38 cm.times.38 cm) square ballistic
test panel was prepared from 53 layers of plain woven Kevlar.RTM.
KM2, 600 denier fiber yarns, having a yarn count of 17 ends per
inch warp and 17 ends per inch fill, extracted yarn tenacities of
25 g/denier warp, and 22 g/denier fill, and an areal density of
2.64 oz/yd.sup.2 (89.5 g/m.sup.2). Individual square fabric layers
were generated by cutting along the warp and fill direction (having
warp and fill fiber yarns parallel to the sides of the square).
Fabric layers were arranged with warp and fill fibers oriented in
the same direction for all fabric layers in the stack. The fabric
layers were stitched together about the perimeter of the panel 1/2
in (1.27 cm) from the edge. A 2 in.times.2 in (5.1.times.5.1 cm)
quilt pattern was also sewn through the thickness of the panel to
mechanically bind the layers together. The backface signature and
V50 results for 44 Magnum bullet ballistic testing at 1430.+-.30
ft/s against a clay witness appear in Table 2.
Comparative Example 5
[0049] A 15 in.times.15 in (38 cm.times.38 cm) square ballistic
test panel was prepared from 26 layers of plain woven Kevlar.RTM.
KM2, 600 denier fiber yarns, having a yarn count of 34 ends per
inch warp and 34 ends per inch fill, extracted yarn tenacities of
21 g/denier warp, and 23 g/denier fill, and an areal density of
5.50 oz/yd.sup.2 (186 g/m.sup.2). Individual square fabric layers
were generated by cutting along the warp and fill direction (having
warp and fill fiber yarns parallel to the sides of the square).
Fabric layers were arranged with warp and fill fibers oriented in
the same direction for all fabric layers in the stack. The fabric
layers were stitched together about the perimeter of the panel 1/2
in (1.27 cm) from the edge. A 2 in.times.2 in (5.1.times.5.1 cm)
quilt pattern was also sewn through the thickness of the panel to
mechanically bind the layers together. Backface signature and V50
results for 44 Magnum bullet ballistic testing at 1430.+-.30 ft/s
against a clay witness appear in Table 2.
Comparative Example 6
[0050] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 33 layers of a 4-harness satin (crow's
foot) weave fabric made from 840 denier Kevlar.RTM. 129 fiber yarns
by JPS Industries Inc, having a yarn count of 20 ends per inch warp
and 20 ends per inch fill, a warp yarn tenacity of 27 g/denier, a
fill yarn tenacity of 25 g/denier, and an areal density of 4.43
oz/yd.sup.2 (150 g/m.sup.2). Individual fabric layers were cut from
the fabric roll having warp and fill yarns parallel to the sides of
the square. Fabric layers were arranged with warp and fill fibers
oriented in the same direction for all fabric layers in the stack.
The fabric layers were stitched together about the perimeter of the
panel 1/2 in (1.27 cm) from the edge. A 2 in.times.2 in
(5.1.times.5.1 cm) quilt pattern was also sewn through the
thickness of the panel to mechanically bind the layers together.
The backface signature and V50 results for 44 Magnum bullet
ballistic testing at 1430.+-.30 ft/s against a clay witness appear
in Table 3.
Comparative Example 7
[0051] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 12 composites fabricated by bonding two
layers of style 726 greige fabric described in Comparative Example
1, the second layer being rotated 45 degrees relative to the first.
The layers were bonded together using a nonwoven polymeric fabric
adhesive (Pellon.RTM. Wonder-Under.RTM. 805 fusible nonwoven
interfacing web available from Pellon.RTM. Consumer Products Group,
LLC of Tucker, Ga.), at a temperature of about 130.degree. C. and
compressed using a hand iron to melt the adhesive and effect a bond
between the fabric layers. The 12 composite layers were stacked and
sewn about the perimeter and with a 2 in.times.2 in (5.1.times.5.1
cm) quilt stitch to generate the test panel. The backface signature
and V50 results for 44 Magnum bullet ballistic testing at
1430.+-.30 ft/s against a clay witness appear in Table 4.
Comparative Example 8
[0052] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 12 layers of the style 726 greige fabric
having properties described in Comparative Example 1, and 6 of the
two 726 greige fabric layer composites described in Comparative
Example 7. The panel was assembled with the 12 non-bonded layers in
front (first impacted by the bullet), and the six composites in the
rear (nearest the clay witness). The resulting stack was sewn about
the perimeter and with a 2 in.times.2 in (5.1.times.5.1 cm) quilt
stitch to generate the test panel. The backface signature and V50
results for 44 Magnum bullet ballistic testing at 1430.+-.30 ft/s
against a clay witness appear in Table 4.
Comparative Example 9
[0053] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from a stack of 17 composites fabricated by
bonding two layers of the 840 denier, 18 ends per inch warp, 18
ends per inch fill greige fabric described in Comparative Example
2, the second layer being rotated 45 degrees relative to the first.
The layers were bonded together using a nonwoven polymeric fabric
adhesive (Pellen.RTM. 805 Wonder-Under.RTM.) under similar
conditions to Comparative Example 7 to melt the adhesive and effect
a bond between the fabric layers. The 17 composite layers were
stacked and sewn about the perimeter and with a 2 in.times.2 in
(5.1.times.5.1 cm) quilt stitch to generate the test panel. The
backface signature and V50 results for 44 Magnum bullet ballistic
testing at 1430.+-.30 ft/s against a clay witness appear in Table
4.
Comparative Example 10
[0054] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 17 layers of the 840 denier Kevlar.RTM. 129
yarn, 18 yarns per inch warp, 18 ends per inch fill greige fabric
described in Comparative Example 2, and 9 of the two layer
composite fabric plies described in Comparative Example 9. The
panel was assembled with the 17 non-bonded layers in front (first
impacted by the bullet), and the six composites in the rear
(nearest the clay witness). The resulting stack was sewn about the
perimeter and with a 2 in.times.2 in (5.1.times.5.1 cm) quilt
stitch to generate the test panel. The backface signature and V50
results for 44 Magnum bullet ballistic testing at 1430.+-.30 ft/s
against a clay witness appear in Table 4.
Comparative Example 11
[0055] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 30 layers of plain weave fabric type
S-17114G with a CS811 finish woven by JPS Industries Inc. from
ultra high molecular weight polyethylene yarn made by the Beijing
Tongyizhong Specialty Fiber Technology & Development Company
Ltd., Beijing, China. This 800 denier yarn reinforcement had a yarn
count of 24 ends per inch (94 ends per 10 cm.) in warp and fill and
had an areal density of 4.86 oz/yd.sup.2 (165 g/m2). Individual
square fabric layers were generated by cutting along the warp and
fill directions (having warp and fill fibers parallel to the sides
of the square). The fabric layers were arranged with warp and fill
fibers oriented in the same direction for all fabric layers in the
stack. The fabric layers were stitched together about the perimeter
of the panel 1/2 in (1.27 cm) from the edge. A 2 in.times.2 in
(5.1.times.5.1 cm) quilt pattern was also sewn through the
thickness of the panel to mechanically bind the layers together.
Ballistic backface signature impact testing was performed using 44
magnum bullets at velocities of 1430.+-.30 ft/s on targets placed
against a clay witness (Roma plastilina clay) following the
protocol outlined by NIJ. The ballistic V50 for 44 magnum bullets
was determined for this test panel. The backface signature and V50
results appear in Table 5.
Example 1
[0056] Diagonal strips were cut from a 63 in (160 cm) wide roll of
the 840 denier Kevlar.RTM. 129 yarn, 18 ends per inch warp, 18 ends
per inch fill greige fabric described in Comparative Example 2. The
diagonal cuts were oriented along the bias direction of this plain
weave fabric as shown in FIG. 3A; generating bias-oriented fabric
strips 28 in (71 cm) in width. The fabric was clamped in a
trellising frame as illustrated in FIG. 3B and extended to achieve
a 45 degree acute trellis angle. The trellised fabric was cut into
equal sections and cross-laid (stacked in an alternating layer
fashion, with every layer having a trellis direction rotated 90
degrees relative to the one before it). The stack was constructed
with the aid of a square pinning frame that held the trellis angle
of individual fabric layers fixed during construction. This
alternating cross-laid arrangement of fabric layers was repeated to
create a stack with 26 trellised fabric layers. The stack of fabric
layers were stitched together about their perimeter, and a 2
in.times.2 in (5.1.times.5.1 cm) quilt pattern was also sewn
through the thickness of the panel to mechanically bind the layers
together, while the fabric layers were held in place in the pinning
frame. The panel was then trimmed to have a 15 in.times.15 in
(38.times.38 cm) end construction. The backface signature and V50
results for 44 Magnum bullets at 1430.+-.30 ft/s against a clay
witness appear in Table 1. These panels fabricated from the
inventive fabric architecture demonstrated a reduction in backface
signature over Comparative Examples 1-3. V50 performance was also
not compromised for these panels with this novel construction,
remaining comparable in value to Comparative Examples 1-3.
Example 2
[0057] Diagonal strips were cut from a 63 in (160 cm) wide roll of
the 600 denier Kevlar.RTM. KM2 yarn, 17 ends per inch warp, 17 ends
per inch fill greige fabric described in Comparative Example 2. The
diagonal cuts were oriented along the bias direction of this plain
weave fabric as shown in FIG. 3A, generating bias-oriented fabric
strips. The fabric was clamped in a trellising frame as illustrated
in FIG. 3B and extended to achieve a 30 degree acute trellis angle.
The trellised fabric was cut into equal sections and cross-laid
(stacked in an alternating layer fashion, with every layer having a
trellis direction rotated 90 degrees relative to the one before
it). The stack was constructed with the aid of a square pinning
frame that held the trellis angle of individual fabric layers fixed
during construction. This alternating cross-laid arrangement of
fabric layers was repeated to create a stack with 27 trellised
fabric layers. The stack of fabric layers were stitched together
about their perimeter, and a 2 in.times.2 in (5.1.times.5.1 cm)
quilt pattern was also sewn through the thickness of the panel to
mechanically bind the layers together, while the fabric layers were
held in place in the pinning frame. The panel was then trimmed to
have a 15 in.times.15 in (38.times.38 cm) end construction. The
backface signature and V50 results for 44 Magnum bullets at
1430.+-.30 ft/s against a clay witness appear in Table 1. This
trellised fabric construction exhibited improved V50 performance
over both the target fabricated of the base 17 end per inch warp,
17 end per inch fill fabric (Comparative example 5) and the plain
woven fabric target of the same 600 denier yarn exhibiting
equivalent individual fabric layer areal density (Comparative
Example 6). The first backface measurement performed on this
inventive construction also demonstrated improvement over both
Comparative Examples 5 and 6, yet the integrity of this
construction after this first backface test was reduced, which may
have resulted in the increased deformation resistance observed in
the second backface signature measurement.
Example 3
[0058] A multilayer panel comprised of a trellised fabric
architecture generated using the 20.times.20 ends per inch, 840
denier Kevlar.RTM. 129 yarn crow's foot weave fabric described in
Comparative Example 6, was generated using the procedure described
for Experimental example 1 above. The finished test panel was
comprised of 23 layers, each having a 45 degree trellis angle, the
layers being stacked in a 0 degree-90 degree alternating
orientation as done in experimental example 1. The panel was sewn
about the perimeter and with a 2 in.times.2 in (5.1.times.5.1 cm)
quilt pattern. The backface signature and V50 results for 44 Magnum
bullets at 1430.+-.30 ft/s against a clay witness appear in Table
3.
[0059] This example exhibited improved backface without significant
loss in V50 when compared with the target fabricated from the base
fabric in Comparative Example 6.
Example 4
[0060] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 12 composites fabric plies fabricated by
bonding two layers of the inventive trellised fabric architecture
fabricated as described in Example 1, the second fabric layer being
rotated 90 degrees relative to the first with respect to trellis
direction. The layers were bonded together using a nonwoven
polymeric fabric adhesive (Pellen.RTM. 805) under similar
conditions to Comparative Example 7 to effect a bond between the
fabric layers. The 12 composite layers were stacked and sewn about
the perimeter and with a 2 in.times.2 in (5.1.times.5.1 cm) quilt
stitch to generate the test panel. As shown in Table 4, this
construction demonstrated higher V50 than the comparative composite
fabric ply panels described in Comparative Examples 7 through 10,
while consistently demonstrating satisfactory backface signatures
even after 5 backface tests performed with the 44 magnum bullet at
1430.+-.30 ft/s.
Example 5
[0061] A 15 in.times.15 in (38.times.38 cm) square ballistic test
panel was prepared from 18 layers of the 840 denier Kevlar.RTM. 129
fiber yarn greige fabric described in Comparative example 2, and 6
trellised fabric composite plies fabricated from this same fabric
as described in experimental example 4. The panel was assembled
with the 18 fabric layers in front (first impacted by the bullet),
and the six composite plies in the rear (nearest the clay witness).
The resulting stack was sewn about the perimeter and with a 2
in.times.2 in (5.1.times.5.1 cm) quilt stitch to generate the test
panel. The backface signature and V50 results for 44 Magnum bullets
at 1430.+-.30 ft/s against a clay witness appear in Table 4.
Experimental Example 6
[0062] Diagonal strips were cut from a roll of style S-17114G,
CS811 polyethylene fabric of Comparative Example 11. The diagonal
cuts were oriented along the bias direction of this plain weave
fabric as shown in FIG. 3A, generating bias-oriented fabric strips.
The fabric was clamped in a trellising frame as illustrated in FIG.
3B and extended to achieve a 50 degree acute trellis angle. The
trellised fabric was cut into equal sections and cross-laid
(stacked in an alternating layer fashion, with every layer having a
trellis direction rotated 90 degrees relative to the one before
it). The stack was constructed with the aid of a square pinning
frame that held the trellis angle of individual fabric layers fixed
during construction. This alternating cross-laid arrangement of
fabric layers was repeated to create a stack with 22 trellised
fabric layers. The stack of fabric layers was stitched together
about the perimeter and a 2 in.times.2 in (5.1.times.5.1 cm) quilt
pattern was also sewn through the thickness of the panel to
mechanically bind the layers together, while the fabric layers were
held in place in the pinning frame. The panel was then trimmed to
have a 15 in.times.15 in (38.times.38 cm) end construction. The
backface signature and V50 results for 44 Magnum bullets at
1430.+-.30 ft/s against a clay witness appear in Table 5. The
trellis fabric construction had a 27% reduction in backface
signature compared to the conventional 0/90 plain weave
construction fabric.
TABLE-US-00001 TABLE 1 Areal Backface Performance density V50
Velocity BFS Example (lbs/ft.sup.2) (fps) (fps) (mm) Comparative
1.034 1535 1444 50 Example 1 1421 51 Comparative 1.008 1558 1429 49
Example 2 1405 56 Comparative 1.040 1590 1434 51 Example 3 1428 45
Example 1 1.034 1559 1428 39 1414 36
TABLE-US-00002 TABLE 2 Areal Backface performance density V50
Velocity BFS Example (lbs/ft.sup.2) (fps) (fps) (mm) Comparative
1.03 1589 1430 52 Example 4 1426 55 Comparative 1.03 1548 1435 48
Example 5 1425 49 Example 2 1.033 1602 1444 42 1448 48
TABLE-US-00003 TABLE 3 Areal Backface performance density V50
Velocity BFS Example (lbs/ft.sup.2) (fps) (fps) (mm) Comparative
1.021 1617 1435 59 Example 6 1426 63 Example 3 1.033 1602 1432 39
1422 48
TABLE-US-00004 TABLE 4 Areal Backface Performance density V50
Velocity BFS Example (lbs/ft.sup.2) (fps) (fps) (mm) Comparative
1.034 1472 1427 37 Example 7 1444 39 1433 35 1405 34 Comparative
1.014 1473 1443 Complete** Example 8 1408 40 Comparative 1.018 1408
1439 Complete Example 9 1424 Complete Comparative 1.011 1471 1427
43 Example 10 1435 56 Example 4 0.992 1510 1408 35 1440 40* 1417 40
1424 36 1446 40 Example 5 0.999 1515 1434 47 1441 42 *denotes
impact 2.5'' from edge of target **"Complete" denotes bullet passed
straight through the target
TABLE-US-00005 TABLE 5 Areal Backface Performance density V50
Velocity BFS Example (lbs/ft.sup.2) (fps) (fps) (mm) Comparative
1.090 1450 1432 51 Example 11 1430 52 Example 6 1.020 1435 1444 39
1442 36
* * * * *