U.S. patent application number 10/388758 was filed with the patent office on 2004-02-05 for ballistic armor.
Invention is credited to Hirschberg, Yoav, Ravid, Moshe.
Application Number | 20040020353 10/388758 |
Document ID | / |
Family ID | 29266769 |
Filed Date | 2004-02-05 |
United States Patent
Application |
20040020353 |
Kind Code |
A1 |
Ravid, Moshe ; et
al. |
February 5, 2004 |
Ballistic armor
Abstract
Ballistic armor for providing ballistic protection from an
impacting projectile threat. The armor comprises a plurality of
composite armor units. Each unit comprises a ceramic body having a
cylindrical body portion with two end faces, one of which is
adapted to face said threat. Each unit further comprises a
non-ceramic belt member assembled with the ceramic body so that
said member contiguously surrounds the cylindrical body portion
without covering the one end face.
Inventors: |
Ravid, Moshe; (Hod Hasharon,
IL) ; Hirschberg, Yoav; (Merom Hagalil, IL) |
Correspondence
Address: |
NATH & ASSOCIATES
1030 15th STREET
6TH FLOOR
WASHINGTON
DC
20005
US
|
Family ID: |
29266769 |
Appl. No.: |
10/388758 |
Filed: |
March 17, 2003 |
Current U.S.
Class: |
89/36.02 |
Current CPC
Class: |
F41H 5/0492 20130101;
F41H 5/0414 20130101; F41H 5/023 20130101 |
Class at
Publication: |
89/36.02 |
International
Class: |
F41H 005/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 2002 |
IL |
149591 |
Claims
1. A composite armor unit for providing ballistic protection from
an impacting projectile threat, the unit comprising a ceramic body
having a cylindrical body portion with two end faces, one of which
is adapted to face said threat, and a non-ceramic belt member
assembled with said ceramic body so that said member contiguously
surrounds said cylindrical body portion without covering said one
end face.
2. A composite armor unit according to claim 1, wherein the ceramic
body and the belt member each has an average density such that the
average density of said member is lower than that of said body.
3. A composite armor unit according to claim 1, wherein the ceramic
body is made from one of the following: Alumina, Silicon Carbide,
Silicon Nitride, Boron Carbide, ceramic glass.
4. A composite armor unit according to claim 1, wherein the belt
member is made from a material having a tensile strength of at
least 3 kg/mm.sup.2.
5. A composite armor unit according to claim 4, wherein said
material is a metallic alloy.
6. A composite armor unit according to claim 5, wherein said alloy
includes one of the following: Aluminum, Titanium, Steel.
7. A composite armor unit according to claim 1, wherein the belt
member is made from one of the following: glass, carbon, aramids,
Kevlar.TM., Nylon, polycarbonates, polyamids, High Density
Poly-Ethylene, carbon fibers.
8. A composite armor unit according to claim 1, wherein the ceramic
body has a diameter and the belt member has a maximal thickness,
which is at most about 10% of said diameter.
9. A composite armor unit according to claim 1, wherein the belt
member includes recesses disposed therein.
10. A composite armor unit according to claim 1, wherein the belt
member is in the form of a spiral.
11. A composite armor unit according to claim 1, wherein the belt
member has a height and thickness, which varies along said
height.
12. A composite armor unit according to claim 1, wherein the belt
member is adapted to provide the cylindrical body portion with
inward radial compression.
13. A composite armor unit according to claim 1, wherein the belt
member has a cup-shape and is adapted to receive said ceramic body
therein.
14. Ballistic armor for providing ballistic protection from an
impacting projectile threat, comprising a plurality of composite
armor units as defined in claim 1.
15. Ballistic armor according to claim 14, further including a
backing layer adapted to trap fragments resulting from the
impacting projectile threat.
16. Ballistic armor according to claim 15, wherein said backing
layer is made from one of the following: aluminum, Spectra.RTM.,
Dyneema.RTM., Kevlar.TM., Twaron.TM., High Density Poly-Ethylene,
aramids, S.sub.2 glass fibers, E glass fibers.
17. Ballistic armor according to claim 14, further including a
frontal spall cover adapted to trap fragments resulting from the
impacting projectile threat.
18. Ballistic armor according to claim 17, wherein said spall cover
is made from one of the following: fiberglass, Kevlar.TM., themoset
resin, thermoplatic resin.
19. Ballistic armor according to claim 14, wherein said units are
bound together by a binding material.
20. Ballistic armor according to claim 19, wherein said binding
material is thermoset plastic.
21. Ballistic armor according to claim 19, wherein said binding
material is a thermoplastic.
Description
FIELD OF THE INVENTION
[0001] This invention relates to ballistic armor and, in
particular, to such armor comprising ceramic bodies.
BACKGROUND OF THE INVENTION
[0002] It is known in the art to provide composite armor plates
with a plurality of juxtaposed ceramic bodies such as tiles,
cylinders, or spheres in order to protect against impacting
ballistic threats.
[0003] U.S. Pat. No. 3,616,115 discloses a composite armor plate
comprising successive layers of small discrete ceramic blocks
encapsulated within a metal matrix by solid-state diffusion
bonding. The ceramic blocks are maintained under compression in
order to increase the amount of energy required by an impacting
projectile to shatter the blocks.
[0004] U.S. Pat. No. 5,361,678 discloses composite armor comprising
ceramic spheres embedded in a metal matrix. The spheres are fully
coated with a binder and ceramic particles in order to insulate
them from thermal shock waves produced by the molten matrix during
the embedding stage, as well as to enhance the ballistic
performance of the armor.
[0005] U.S. Pat. No. 6,112,635 discloses a composite armor plate
for absorbing and dissipating kinetic energy from a high velocity,
armor-piercing projectile, the plate comprising a single layer of
ceramic cylinders arranged in a plurality of adjacent rows. The
cylinders are in direct contact with each other and are bound by a
solidified material.
SUMMARY OF THE INVENTION
[0006] The present invention suggests ballistic armor for providing
ballistic protection from an impacting projectile threat, the armor
comprising a plurality of composite armor units, each comprising a
ceramic body having a cylindrical body portion with two end faces,
one of which is adapted to face said threat, and a non-ceramic belt
member assembled with said ceramic body so that said member
contiguously surrounds said cylindrical body portion without
covering said one end face.
[0007] Preferably, each composite armor unit according to the
present invention is bound to other such units by a binding
material to form the armor. The armor preferably further comprises
a backing layer as is known in the art for trapping fragments of
the armor ejected by the impact of the projectile threat.
[0008] The cylindrical body portion of the ceramic body, from which
the composite armor unit of the present invention is assembled, may
have different cross-sectional shapes such as e.g. circular,
polygonal, or the like.
[0009] The end faces of the ceramic body may be flat, and one may
thereby constitute a base for the body portion. As additional
examples, the end faces may be convex, bulging away from the body
portion, or they may be concave, dipping into said portion. Various
such designs may enhance the ballistic performance of the armor or
yield other advantages. The two end faces may not necessarily be of
the same design.
[0010] The ceramic body of the composite armor unit according to
the present invention may be made of any known armor ceramic
material, such as Alumina, Silicon Carbide, Silicon Nitride, Boron
Carbide, or any other refractory material such as ceramic glass and
the like. A ceramic material containing reinforcing fibers, as
known in the art, may also be used.
[0011] The belt member, assembled with the ceramic body in
accordance with present invention, has an outer perimeter, and an
inner perimeter defining a hollow region to receive and adjoiningly
surround the ceramic body to fit about its cylindrical portion. The
inner perimeter of the belt member is designed to conform to the
shape of said cylindrical body portion to enable the member to
closely hug the body after assembly. The outer perimeter of the
belt member may be of any design and its dimensions and/or shape
may vary along the height of the belt member.
[0012] The belt member according to the present invention
advantageously allows for a variety of possible shapes and sizes
for its outer perimeter. For example, the outer perimeter of the
belt member may be circular, elliptical, rectangular, otherwise
polygonal, or may have an irregular shape but it is preferable that
it have a simple geometry to facilitate its manufacture. Such
possibilities allow the composite armor unit and the ballistic
armor of the present invention to be suited to a wide range of
needs. For example, the belt member may have a hexagonal outer
perimeter to allow the unit with which it is assembled to be
contiguous with neighboring units in the armor, thereby eliminating
the interstices between the units and increasing ballistic immunity
to smaller projectile threats. As another example, in order to
reduce weight of the unit, and therefore the armor, the belt member
may have recesses, such as holes or depressions, formed therein or
may have a thickness which varies along its height. In addition,
the belt member may not necessarily extend along the entire height
of the cylindrical body portion of the ceramic body with which it
is assembled, but rather may, for example, have a ring-like shape
to simply adjoin the perimeter of the body at a certain height. The
above two design possibilities may both be embodied together in the
belt member when in the form of a spiral, for example. The spiral
belt member may extend along the majority of the ceramic body with
which it is assembled, with a space separating successive turns of
the spiral. In this way, the spiral design of the belt member
serves to reduce the weight of the unit without sacrificing its
ballistic performance.
[0013] The belt member of the present invention may be made of a
variety of materials so long as the belt member possesses a minimal
amount of tensile strength, which is at least about 3 kg/mm.sup.2.
Possible materials include but are not limited to metal alloys such
as Aluminum, Titanium and Steel alloys, composites TM such as
glass, carbon and aramids, Kevlar.TM., high strength plastics such
as Nylon, polycarbonates, and polyamids, High Density Poly-Ethylene
(HDPE) within various resins, carbon fibers and the like. The
various resins may include simple fabric, winded fabrics, or mats
reinforcement resins.
[0014] Calculations that will be presented below show that one of
the main advantages provided by ballistic armor comprising
composite armor units according to the present invention, is a much
desired geometrical weight reduction per unit area of armor. To
maximize this advantage, the average density of the belt member
should be less than that of the ceramic material from which the
body is made. The average density of the belt member depends not
only on the material from which it is made, but also on its design.
Providing the belt member with depressions as mentioned above, for
example, would serve to reduce its average density.
[0015] The geometrical weight reduction enabled by the present
invention is achieved by providing each of the composite armor
units, from which the armor is composed, with a belt member of such
a design as to reduce each unit's average density without
decreasing its ballistic effectiveness. Determination of the
optimal design of the belt member may be made by computer
calculation and simulation or by trial and error, bearing in mind
the nature of the expected threat from which ballistic protection
is desired, in particular the types, calibers, ranges, and
inclinations of the impacting projectiles. In general, the most
important parameter to consider in selecting such a design is the
maximal thickness t of the belt member.
[0016] It is clear from the above that the maximal possible
reduction in the average density of the composite armor unit and
the ballistic armor of the present invention is dictated by the
necessity to keep the ballistic performance of the armor at a high
level so that it may protect against the expected impacting
projectile threat. Indefinitely increasing the thickness t of the
belt member will surely further reduce the weight of the armor but
at some point, ballistic performance will also be compromised. It
was found that both significant geometrical weight reduction is
achieved and high ballistic performance is maintained so long as
the thickness t of the belt member does not surpass about 10% of
the ceramic body's diameter D.
[0017] The minimal reduction of the average density or weight of
the body that would still be considered essential is limited by the
need to justify the costs of manufacturing a belt member according
to the present invention. Thus, while the provision of a belt
member having a thickness of 0.01%, for example, of the diameter D
of the ceramic body would also render the composite armor unit
lighter to some minor extent, this would not constitute an
essential reduction in the unit's average density as it is not
sufficiently beneficial to justify such a belt member's
manufacture. In general, a belt member having a thickness t of at
least about 1% of the diameter D would be considered an essential
reduction.
[0018] The composite armor unit of the present invention employed
in ballistic armor provides additional advantages, which increase
the armor's ballistic effectiveness. Firstly, the belt member of
the present invention confines the cylindrical body on which it is
mounted so that upon a projectile's impact on the body, the member
radially resists and delays ceramic fracture of the body outwardly
towards the member's perimeter and also applies resistance forces,
which prevent penetration of the projectile. In addition, the belt
member provides separation between the cylindrical bodies, which
along with the radial confinement it affords, prevents one body's
ceramic fracture due to projectile impact from affecting
neighboring bodies. In order to enhance these two advantages, the
belt member may be assembled with the body so as to hug the body
tightly providing it with inward radial compression, thereby
increasing resistance. Both of the above advantages increase the
armor's multi-hit capability, allowing it to withstand a plurality
of projectile impacts while maintaining high ballistic performance.
In certain circumstances, the latter advantages may be crucial to
the point of being preferable over a reduction in weight, in which
case heavier materials may be used to form the belt members in
order to enhance ballistic performance at the expense of
geometrical weight gain.
[0019] The ballistic armor of the present invention is preferably
assembled from a single layer of composite armor units, but may
also be formed from a plurality thereof. The composite armor units
may or may not be in direct contact with each other. The ballistic
armor is preferably in the form of a plate and may be curved to
allow it to conform to various surfaces whose ballistic protection
is desired. The binding material used to hold the units together
may be any known suitable material such as thermoset plastic (e.g.
epoxy resin or polyurethane) and thermoplastic material (e.g.
polyester, polycarbonate, polyamid). The backing layer of the
ballistic armor in accordance with the present invention serves to
trap ceramic fragments as well as the residual deformed projectile
or fragments thereof, resulting from its impact and penetration.
The backing layer may be made of any suitable material known in the
art, e.g. aluminum, woven or unidirectional fabric laminates
comprising Spectra.RTM., Dyneema.RTM., Kevlar.TM., Twaron.TM.,
S.sub.2 or E glass fibers, HDPE, aramids and the like within
various resins. The armor preferably also includes a cover
material, such as a frontal spall cover, to cover and seal the
front of the armor and to keep the units in place, as well as to
minimize outward deflection of the impacting projectile threat,
fragments of the threat or the units resulting from impact and/or
other frontal debris. The cover material is preferably made from
layers of fibers, such as Kevlar.TM. and fiberglass, saturated
within thermoplastic and thermoset resins.
[0020] The ballistic armor according to the present invention may
further include an intermediate layer, as known in the art, between
the composite armor units of the present invention and the backing
layer to provide a stand-off distance, enhancing the ballistic
effectiveness of the armor. Such an intermediate layer may have any
design, such as a cellular honeycomb arrangement, and may be made
of any appropriate substance, such as foamed materials. Other
components known in the art to be used in composite ballistic armor
technology may also be added to the armor of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to understand the invention and to see how it may
be carried out in practice, a preferred embodiment will now be
described, by way of non-limiting example only, with reference to
the accompanying drawings, which are not necessarily drawn to scale
and are provided merely for the purpose of illustration,
include:
[0022] FIG. 1 is ballistic armor according to the present
invention;
[0023] FIG. 2A is a ceramic cylinder used in composite armor
technology as known in the art;
[0024] FIG. 2B is a cross-section of an armor plate as known in the
art comprising ceramic cylinders of the kind shown in FIG. 2A;
[0025] FIG. 3A is a composite armor unit according to the present
invention;
[0026] FIG. 3B is a cross-section of a piece of ballistic armor
shown in FIG. 1 according to the present invention;
[0027] FIG. 4A is another embodiment of the composite armor unit in
accordance with the present invention;
[0028] FIG. 4B is a cross section of the composite armor unit shown
in FIG. 4A;
[0029] FIG. 4C is yet another embodiment of the composite armor
unit in accordance with the present invention;
[0030] FIG. 4D is a cross section of the composite armor unit shown
in FIG. 4C;
[0031] FIG. 4E is yet another embodiment of the composite armor
unit in accordance with the present invention;
[0032] FIG. 4F is a cross section of the composite armor unit shown
in FIG. 4E;
[0033] FIG. 4G is yet another embodiment of the composite armor
unit in accordance with the present invention;
[0034] FIG. 4H is a cross section of the composite armor unit shown
in FIG. 4G.
DETAILED DESCRIPTION OF THE INVENTION
[0035] FIG. 1 shows a section of a ballistic armor 30 according to
the present invention for providing protection from an impacting
projectile threat P. The armor 30 comprises a plurality of
composite armor units 32 according to the present invention
arranged in a single layer of parallel rows. Each unit 32 is
assembled from a cylindrical ceramic body 34 having one flat end
face and one convex end face adapted to face the threat P, and from
a belt member 36 mounted thereon in accordance with the present
invention. The belt member 36 is a thin-walled tube whose circular
inner and outer perimeters conform to the shape of the cylindrical
ceramic body 34. Each belt member 36 contiguously surrounds one
cylindrical ceramic body 34 to form one unit 32. The units 32 are
in direct contact with each other forming interstices 38
therebetween. The units 32 are bound together by a binding material
40, which occupies the interstices 38, as well as the periphery of
the armor 30. The armor 30 further includes a backing layer 42
covering the flat end faces of the bodies 34 on the rear side. On
its front side, the armor 30 includes a spall cover 44 covering the
convex end faces of the bodies 34 and sealing the units 32 in
place.
[0036] The cylindrical ceramic bodies 34 are made by standard
methods of ceramic manufacturing known in the art. The belt member
36 is produced in different ways corresponding to the material from
which it is made. For example, for alloys of Aluminum, Steel, or
Titanium, any known metallic production methods, such as extrusion,
may be employed. For belt members 36 made of fiberglass,
Kevlar.TM., or carbon, for example, filament-winding manufacturing
methods are used. In any case, the belt member 36 is made so that
its inner diameter matches closely to the diameter D of the ceramic
body 34 to allow it to be mounted thereon by simple sliding.
[0037] To assemble the composite armor unit 32 according to the
present invention, a single belt member 36 is mounted onto one
ceramic body 34 by hand or by machine.
[0038] The geometrical weight reduction achieved by the assembly of
the belt member 36 in the composite armor unit 32 according to the
present invention can be best understood by comparing composite
armor as known in the prior art with ballistic armor 30 in
accordance with the present invention.
[0039] FIG. 2A shows a typical, known ceramic cylinder 2 with a
circular cross-section and one convex end face 4 adapted to face an
impacting projectile threat. FIG. 2B is a cross-section of a piece
of composite armor plate 6 comprising three ceramic cylinders 2 as
shown in FIG. 2A, each cylinder 2 having a diameter D and being
arranged in close contact as is known in the art and creating
interstitial spaces 8 between them. The cylinders 2 are typically
held in place by resins (not shown) occupying the spaces 8 and are
covered by layers of ballistic fabric (not shown). Since they
typically contain material lighter than ceramic, the interstitial
spaces 8 serve to decrease the weight of the plate 6 whilst being
small enough not to reduce its ballistic performance.
[0040] A first imaginary equilateral triangle 10 may be considered
by connecting the centers of the three cylinders 2 in FIG. 2B. The
triangle 10 may be taken as a representative area for the entire
plate according to which the ceramic cylinder's weight proportion
.eta..sub.0 may be calculated. Using the geometry of the triangle
10, it can be shown that: 1 0 = 2 3 = 0.906
[0041] Therefore, approximately 91% of the area of the plate 6 is
occupied by ceramic material, which is the plate's heaviest and
most abundant component. The interstitial spaces 8, which are fully
or partially filled with resin, constitute the remaining 9% of the
plate's area.
[0042] FIG. 3A shows the composite armor unit 32 according to the
present invention assembled from the ceramic body 34, which is
similar to the cylinder 2 shown in FIG. 2A. The ceramic body 34
also has a diameter D and includes the belt member 36 in accordance
with the present invention mounted thereon. FIG. 3B is a
cross-section of a piece 46 of the ballistic armor 30 shown in FIG.
1 comprising three composite armor units 32 as shown in FIG. 3A,
the units 32 being arranged and bound similarly to the cylinders 2
in FIG. 2A. The belt members 36 have a thickness t and as a result
each unit 32 has a diameter D+2 t, which is larger than that of
cylinder 2. Consequently, interstice 38 is larger in area than
interstitial space 8.
[0043] A second imaginary equilateral triangle 48, may be
considered by connecting the centers of the three bodies 34 in FIG.
3B and may be taken as a representative area for the entire armor
30 according to which the armor unit's weight proportion .eta. may
be calculated. Using the geometry of the triangle 48, it can be
shown that if .times. is a ratio between the thickness t of the
belt member 36 and the diameter D of the body 34, namely
.times.=t/D, then the armor unit's weight proportion .eta. for belt
members 36 of average density .rho..sub.bm and ceramic bodies 34 of
average density .rho..sub.cb is 2 = 2 3
[0044] where the factor .phi. is given by: 3 = 1 + 4 x ( bm cb ) (
1 + 2 x ) 1 + 4 x
[0045] It is clear from the above that when .times.=0 (i.e. when
there is no belt member 36), then .eta.=.eta..sub.0.
[0046] The above calculations show that as long as the belt members
36 have a lower average density than the ceramic cylindrical bodies
34 (i.e. .rho..sub.bm<.rho..sub.cb), the factor .phi. will be a
fraction and the armor unit's weight proportion .eta. will be less
than the ceramic cylinder's weight proportion .eta..sub.0 (i.e.
.eta.<.eta..sub.0). The latter, in addition to the enlarged area
of interstice 38 in comparison with interstitial space 8, renders
the weight per unit area of armor 30 lower than that of the plate
6.
[0047] The following table shows an example of possible extents of
weight reduction as a function of the ratio x for ballistic armor
comprising composite armor units according to the present invention
assembled from a cylindrical body made from 98% Alumina
(A.sub.2O.sub.3) and having an average density of .rho..sub.cb=3.84
g/cm.sup.3, with a belt member made from an Aluminum alloy and
having an average density of .rho..sub.bm=2.75 g/cm.sup.3 mounted
thereon:
1 Approximate weight .chi. .PHI. .eta. reduction 0.01 0.989 0.896
10% 0.02 0.978 0.886 11% 0.03 0.968 0.877 12% 0.04 0.958 0.868 13%
0.05 0.949 0.860 14% 0.06 0.940 0.851 15% 0.07 0.931 0.843 16% 0.08
0.922 0.836 16% 0.09 0.914 0.828 17% 0.1 0.906 0.821 18%
[0048] As can be seen above, for a ratio .times. of 0.1, a weight
reduction per unit area of about 18% over the plate shown in FIG.
2B can be achieved without a significant decrease in ballistic
performance.
[0049] For a given projectile threat P, the number, size, shape,
and arrangement of the composite armor units 32 in the ballistic
armor 30 of the present invention yielding the optimal ballistic
performance may be selected by trial and error. In the present
example, the following parameters have been used and results
achieved for the units 32 arranged as shown in FIG. 1, for
successfully and repeatedly protecting from the threat of 14.5 mm
caliber API-B32 armor piercing bullets fired from an equivalent
range of 250 meters, at an inclination of 0.degree. (Nato) and
having an impact velocity of 890 m/s):
[0050] Ceramic material of ceramic body--98% Alumina
(Al.sub.2O.sub.3)
[0051] Density (specific gravity) of ceramic material: 3.84
g/cm.sup.3
[0052] Dimensions of cylindrical body: circular base of diameter
D=19 mm; height of 19 mm; convex spherical end faces having radii
of curvature of R=31 mm.
[0053] Material of belt member: Al 6063T6
[0054] Thickness of belt member: t=0.7 mm
[0055] The armor plate in the form of an add-on module is bolted to
a 7.3 HHS (MIL-A-46100D) surface, for which enhanced ballistic
protection is desired. The plate includes a 10 mm Kevlar.TM.
backing layer weighing 14 g/m.sup.2. It was shown that an armor
plate with the above parameters weighs 65 kg/M.sup.2, in comparison
to an identical competing plate (as in FIG. 2B) not employing the
belt member of the present invention, which weighs 69 kg/m.sup.2.
This considerable 5.8% decrease in weight is achieved without any
reduction in the plate's ballistic performance for the above threat
as well as for other projectiles. In fact, the ballistic
performance is improved by 10% as the multi-hit capability is found
to yield a 90 mm spacing between shots, whereas the competing plate
yields a 100 mm spacing between shots.
[0056] Clearly, various modifications within the scope of the
composite armor unit and ballistic armor according to the present
invention may be made. For example, FIG. 4A shows a composite armor
unit 50 in accordance with present invention assembled from a
cylindrical body 51 with two convex spherical end faces and a belt
member 52 mounted thereon having a circular inner perimeter to
tightly surround the body 51, and a hexagonal outer periphery. The
belt member 52 includes depressions 53 formed therein to further
reduce the average density of the member 52, and thereby the
geometrical weight of the unit 50. A cross-section of the unit 50
is shown in FIG. 4B. In order to achieve extremely high ballistic
performance, such hexagonal units may be used in ballistic armor to
form a contiguous plate devoid of interstitial spaces. The
depressions 53 aid to offset the gain in weight resulting from the
absence of the interstitial spaces.
[0057] FIG. 4C shows yet another embodiment of the composite armor
unit according to the present invention. The unit 60 is assembled
from a substantially cylindrical body 61 having a hexagonal
perimeter and two flat end faces. The belt member 62 mounted on the
body 61 has a ring-like shape and does not extend along the entire
height of the body 61, but rather contiguously surrounds only a
central portion thereof. As can be seen in the cross-section of the
unit 60 in FIG. 4D, the member 62 has both a hexagonal inner
perimeter to conform to the body 61, and a hexagonal outer
perimeter. The ring-like design for the belt member 62 serves to
further reduce the geometrical weight of the unit 60, but also
allows for ballistic armor devoid of interstitial spaces and
therefore having high ballistic performance.
[0058] FIG. 4E shows yet another embodiment of the composite armor
unit 70 according to the present invention. The unit 70 is
assembled from a cylindrical body 71 having one flat end face as
its base and one convex end face adapted to face the projectile
threat. The belt member 72, which has a circular inner and outer
perimeter, includes indentations 73 formed therein, as can be seen
in a cross-section of the unit 70 shown in FIG. 4F. The
indentations 73 serve to reduce the geometrical weight of the unit
70 without sacrificing ballistic performance. As is also shown in
FIG. 4F, the belt member 72 is in the form of a cup within which
the body 71 sits. The belt member 72 extends to cover the base of
the body 71 and includes a through hole 74 on its underside below
the base of the body 71. During assembly of the unit 70, the body
71 is placed into the cup-shaped belt member 72 and pressed down
until its base contacts the bottom of the member 72. Since the belt
member 72 contiguously surrounds the body 71, air occupying the
cup-shaped belt member 72 cannot escape along its walls when the
body 71 is placed therein, and therefore exits via the through hole
74 designed for this purpose.
[0059] FIG. 4G shows yet another embodiment of the composite armor
unit 80 according to the present invention. The unit 80 is
assembled from a cylindrical body 81 having one flat end face as
its base and one convex end face adapted to face the projectile
threat. The belt member 82, which has a circular inner and outer
perimeter, is in the form of a spiral. The member 82 is mounted on
the body 81 and extends along a majority of its height. As is also
shown by the cross-section of the unit 80 in FIG. 4H, spaces 83
present between successive turns of the spiral belt member 82 serve
to reduce the geometrical weight of the unit 80 without sacrificing
ballistic performance.
[0060] It should be understood that the above described embodiments
are only examples of composite armor units and ballistic armor
comprising them in accordance with the present invention, and that
the scope of the present invention fully encompasses other
embodiments which may become obvious to those skilled in the
art.
* * * * *