U.S. patent application number 11/989751 was filed with the patent office on 2011-04-14 for multi-functional armor system.
This patent application is currently assigned to PLASAN SASA LTD.. Invention is credited to Yoav Hirschberg, Mark Pak, Moshe Ravid.
Application Number | 20110083549 11/989751 |
Document ID | / |
Family ID | 37106260 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110083549 |
Kind Code |
A1 |
Ravid; Moshe ; et
al. |
April 14, 2011 |
Multi-Functional Armor System
Abstract
A ballistic armor adapted to protect against armor piercing
projectiles and to withstand multiple impacts of fragment
simulating projectiles of a predetermined type, traveling at an
initial velocity not exceeding a first velocity. The armor
comprises a main armor layer and an auxiliary layer. The main armor
layer is adapted to absorb most of the energy of the armor piercing
projectiles and to withstand the impacts of the fragment simulating
projectiles traveling at a velocity not exceeding a second velocity
which is lower than said first velocity. The auxiliary layer is
disposed in front of the main armor layer to face the projectiles,
and is made of a material which is adapted to undergo a ductile
failure mode when perforated by said fragment simulating
projectiles and thereby experience localized deformation in the
vicinity of each perforation, and which is adapted to cause the
fragment simulating projectiles to experience such an energy loss
associated with the perforation and deformation as to reduce their
velocity from the initial velocity to a velocity not exceeding the
second velocity.
Inventors: |
Ravid; Moshe; (Hod Hasharon,
IL) ; Pak; Mark; (Karmiel, IL) ; Hirschberg;
Yoav; (M P Merom Hagalil, IL) |
Assignee: |
PLASAN SASA LTD.
M.P. Marom Hagalil
IL
|
Family ID: |
37106260 |
Appl. No.: |
11/989751 |
Filed: |
July 27, 2006 |
PCT Filed: |
July 27, 2006 |
PCT NO: |
PCT/IL2006/000874 |
371 Date: |
January 31, 2008 |
Current U.S.
Class: |
89/36.02 ;
89/904; 89/907; 89/910; 89/930 |
Current CPC
Class: |
F41H 5/0421 20130101;
F41H 5/045 20130101; F41H 5/0492 20130101 |
Class at
Publication: |
89/36.02 ;
89/904; 89/910; 89/930; 89/907 |
International
Class: |
F41H 5/04 20060101
F41H005/04; F41H 7/02 20060101 F41H007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2005 |
IL |
170119 |
Apr 5, 2006 |
IL |
170119/2 |
Claims
1. Ballistic armor adapted to protect against armor piercing
projectiles and to withstand multiple impacts of fragment
simulating projectiles of a predetermined type, traveling at an
initial velocity not exceeding a first velocity, the armor
comprising: (a) a main armor layer designed to absorb most of the
energy of the armor piercing projectiles and to withstand the
impacts of said fragment simulating projectiles traveling at a
velocity not exceeding a second velocity which is lower than said
first velocity; and (b) an auxiliary layer disposed in front of the
main armor layer to face the projectiles, the auxiliary layer being
made of a material which is adapted to undergo a ductile failure
mode when perforated by said fragment simulating projectiles and
thereby experience localized deformation in the vicinity of each
perforation; said auxiliary layer being adapted for being
perforated by said fragment simulating projectiles such that an
energy loss of the projectiles associated with said perforation and
deformation gives rise to a reduction in their velocity from said
initial velocity to a velocity not exceeding said second
velocity.
2. Ballistic armor according to claim 1, wherein the material of
which the auxiliary layer is made is characterized in that its
Brinell hardness is not greater than 165 kg.sub.f/mm.sup.2.
3. Ballistic armor according to claim 1, wherein the material of
which the auxiliary layer is made is characterized in that: (a) its
elongation is greater than 8 percent; and (b) its yield strength is
not greater than 52 kg.sub.f/mm.sup.2.
4. Ballistic armor according to claim 1, wherein the auxiliary
layer is made of an aluminum alloy.
5. Ballistic armor according to claim 4, wherein the aluminum alloy
is a selected from the group comprising aeronautical alloys and
commercial alloys.
6. Ballistic armor according to claim 1, wherein the auxiliary
layer is spaced less than 100 mm from the main armor layer.
7. Ballistic armor according to claim 1, wherein the auxiliary
layer is in contact with the main armor layer.
8. Ballistic armor according to claim 1, wherein the fragment
simulating projectiles are up to 20 mm in diameter and said first
velocity is 1500 m/s.
9. Ballistic armor according to claim 1, wherein the main armor
layer comprises a base layer made of a high density material.
10. Ballistic armor according to claim 9, wherein the high density
material is high hardness steel.
11. Ballistic armor according to claim 10, adapted for mounting on
a sidewall of a vehicle to protect at least one region thereof,
wherein said base layer is at least partially constituted by said
sidewall at said at least one region.
12. Ballistic armor according to claim 1, wherein the main armor
layer further comprises an additional layer.
13. Ballistic armor according to claim 11, wherein the main armor
layer further comprises an additional layer which is in the form of
an add-on layer mounted to said sidewall at said at least one
region.
14. Ballistic armor according to claim 12, wherein the additional
layer comprises a plurality of pellets or tiles held together by a
binder material.
15. Ballistic armor according to claim 14, wherein the pellets or
tiles comprise a refractory material.
16. Ballistic armor according to claim 14, wherein the pellets or
tiles comprise ballistic ceramic.
17. Ballistic armor according to claim 16, wherein the ceramic is
selected from the group comprising alumina, silicon carbide,
silicon nitride, and boron nitride.
18. Ballistic armor according to claim 14, wherein the pellets or
tiles are made of ultra high hardness steel.
19. Ballistic armor according to claim 1, wherein the main armor
layer further comprises an inner protective liner attached thereto
on its side facing away from said auxiliary layer.
20. Ballistic armor according to claim 19, wherein the inner
protective liner is fiberglass.
21. Ballistic armor according to claim 19, wherein the inner
protective liner comprises aramid.
22. Ballistic armor according to claim 19, wherein the inner
protective liner comprises high density polyethylene.
23. Ballistic armor according to claim 19, wherein the inner
protective liner comprises a hybrid material.
24. Ballistic armor according to claim 1, wherein the main armor
layer comprises dual hardness armor.
25. A method of ballistic protection against armor piercing
projectiles and multiple impacts of fragment simulating projectiles
of a predetermined type, each traveling at its initial velocity not
exceeding a first velocity, method comprising: (a) providing a main
armor layer adapted to absorb most of the energy of the armor
piercing projectiles and to withstand the impacts of said fragment
simulating projectiles traveling at a velocity not exceeding a
second velocity which is lower than said first velocity; (b)
providing an auxiliary layer made of a material which is adapted to
undergo a ductile failure mode when perforated by said fragment
simulating projectiles and thereby experience localized deformation
in the vicinity of each perforation; and (c) disposing said
auxiliary layer in front of said main armor layer so as to face the
projectiles and to cause said fragment simulating projectiles to
experiences such an energy loss associated with said perforation
and deformation as to reduce their velocity from said initial
velocity to a velocity not exceeding said second velocity.
Description
FIELD OF THE INVENTION
[0001] This invention relates to ballistic armor, particularly
those suited to protect against fragmentation.
BACKGROUND OF THE INVENTION
[0002] When designing ballistic armor, for example, for protecting
a vehicle, consideration must be given to the type or types of
projectile against which the armor must protect. Some arrangements
of armor will not protect at all against a certain type of
projectile. For example, an array of ceramic tiles or pellets can
protect against kinetic energy (KE) threats, such as direct hits of
armor-piercing penetrators, while they generally do not provide
protection against a plurality, i.e., hundreds, of fragments
traveling at a high rate of speed as a consequence of an improvised
explosive device (IED) exploding in the vicinity of an armored
vehicle. Typically, the heavy fragmentation impacts resulting from
the explosion of an IED destroy the hard, brittle ceramic, exposing
the vehicle to be pierced by direct hit shots of sniper rifles or
other similar threats.
[0003] When performing ballistic tests, it is not practical to
explode an IED near an armor prototype. Therefore,
fragment-simulating projectiles (FSPs) of different types are used.
The impact of an FSP having a certain velocity on ballistic armor
simulates the impact of a fragment resulting from an explosion of a
known class of IED. Different size FSPs and their impact velocities
correspond to different IEDs, such as mortars or artillery shells
of a given diameter. By testing the armor prototype with an FSP,
its ballistic capability against an IED threat can be
determined.
[0004] An important consideration which must be taken into account
when designing ballistic armor is the weight per coverage area of
the armor. Theoretically, armor can be constructed to protect
against almost any threat or combination of threats. On the other
hand, the resulting weight of the armor needed for such protection
has to be practical for the intended use, especially when the
protection of vehicles such as trucks, armored infantry fighting
vehicles, or armored personnel carriers, is concerned.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to lightweight ballistic
armor which can protect against both armor piercing projectiles and
high speed fragments resulting from a nearby explosion of an IED or
a high energy shell.
[0006] According to the present invention, there is provided a
ballistic armor adapted to protect against armor piercing
projectiles and to withstand multiple impacts of FSPs of a
predetermined type, traveling at an initial velocity not exceeding
a first specified velocity, and a method of such protection.
[0007] The armor comprises a main armor layer and a front auxiliary
layer facing the projectiles, the main armor layer being adapted to
absorb most of the energy of the armor piercing projectiles and to
withstand the impacts of said FSPs when their velocity does not
exceed a second velocity which is lower than the first specified
velocity. The auxiliary layer is adapted for being perforated by
said FSPs such the deformation of the auxiliary layer caused by its
perforation by the FSPs is localized in the area of each
perforation and the energy loss of the FSPs associated with the
deformation and perforation gives rise to a reduction in velocity
of the FSPs from their initial velocity to a velocity not exceeding
the second velocity.
[0008] In order to be capable of the deformation as described
above, the auxiliary layer is made of a material that, when
perforated, undergoes ductile failure mode, also known as ductile
exit. This mode as well as the associated perforation mechanism is
described in detail in "Dynamic Perforation of Viscoplastic Plates
by Rigid Projectiles" (M. Ravid & S. R. Bodner, International
Journal of Engineering Science, Vol. 21, No. 6, pp 577-591, 1983)
and "Penetration into Thick Targets--Redefinement of a 2D Dynamic
Plasicity Approach" (M. Ravid & S. R. Bodner, International
Journal of Impact Engineering, Vol. 15. No. 4, pp 491-499,
1994.
[0009] The material of which the auxiliary layer is made is further
characterized in that it is of such hardness and thickness that
sufficient energy of the FSPs is absorbed thereby to ensure the
reduction in velocity of the FSPs from their initial velocity to a
velocity not exceeding the second velocity. Experimental results
show that this is obtained in materials whose the Brinell hardness
is in the range of about 65 to about 165 kg.sub.f/mm.sup.2.
Additionally, it is desirable that the material have an elongation
greater than about 8%, and the yield strength in the range between
about 11 and about 52 kg.sub.f/mm.sup.2 when tested at standard
quasi-static test conditions.
[0010] Examples of materials having the above properties, and
therefore suitable to be used for the auxiliary layer in the armor
of the present invention, are aluminum alloys such as Al 6061, Al
7075, Al 2024, Al 5083, Al 7017, or Al 7019, and materials having
similar properties.
[0011] Experiments show that the use of the auxiliary layer made of
aluminum alloys as described above allows the armor to stop FSPs of
diameters as large as 20 mm having velocities as high as 1500 m/s.
This is a surprising effect, since aluminum is known to have
relatively low ballistic protection capabilities when used as a
frontal material, for which reason it is normally used in internal
or backing layers. It is further surprising that commercial and
common aeronautical alloys may be used successfully for ballistic
protection as suggested in accordance with the present invention,
though normally only special armor alloys are used for military
applications. While there may be no significant weight difference
between military and non-military aluminum alloys, the latter are
normally less hard and are cheaper than the former.
[0012] The main armor layer may comprise a base layer made from a
high density material of an appropriate thickness, such as high
hardness steel and an additional, e.g., an add-on, layer. The
latter may, for example, be of the kind comprising a plurality of
tiles or pellets with or without a composite backing. The tiles or
pellets may be made from, or comprise, metal (such as ultra high
hardness steel) or a refractory or ceramic material such as alumina
(Al.sub.2O.sub.3), silicon carbide (SiC), silicon nitride
(Si.sub.3N.sub.4), or boron carbide (B.sub.4C). The add-on layer
typically is a frontal layer with respect to the base layer. The
main armor layer may also be provided with an inner liner, which
covers the base layer from behind. When the armor is designed to
protect a vehicle, in particular its sidewall, the base layer may
be constituted by said sidewall and the inner liner may be attached
to the sidewall so as to protect the interior of the vehicle from
shrapnel, and for absorbing remaining kinetic energy from armor
piercing projectiles and fragments. The inner liner may be made
from or comprise aramid materials, fiberglass, HDPE or laminated
hybrids of such materials.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In order to understand the invention and to see how it may
be carried out in practice, embodiments will now be described, by
way of non-limiting examples only, with reference to the
accompanying drawings, in which:
[0014] FIG. 1 is a schematic cross-sectional side view of ballistic
armor according to one embodiment of the present invention; and
[0015] FIG. 2 is a schematic cross-sectional side view of ballistic
armor according to another embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0016] FIG. 1 is a schematic representation of ballistic armor 10
according to one embodiment of the present invention, adapted to
protect a vehicle (not shown) against both a fragment-simulating
projectile (FSP) and an armor piercing projectile (APP) traveling
in the direction indicated by arrow X.
[0017] The armor 10 comprises an auxiliary layer 12 and a main
armor layer, which may or may not be separated by a gap 22, as
shown in FIGS. 1 and 2.
[0018] The main armor layer 14 comprises a base layer 16, an add-on
layer 18 and, optionally, an inner liner 20.
[0019] The base layer 16 is typically made from a hard metallic
material such as RHA or high hardness steel which may have a
thickness between 4 mm and 20 mm. In the present embodiment, this
layer is constituted by the sidewall of the vehicle protected by
the armor 10.
[0020] Alternatively, the base layer may comprise dual hardness
armor (DHA). For example, such DHA may comprise a layer of UHH
steel facing the projectile, and a layer of HH steel therebehind,
the two layers being integrally attached to each other to form the
base layer. The UHH layer may be thinner than the HH layer, e.g.,
its thickness may be about one third of the total thickness of the
DHA, and the thickness of the HH layer may be two thirds thereof.
With the base layer being made of DHA, the armor may provide an
essentially enhanced ballistic protection.
[0021] The add-on layer 18 comprises an array of tiles or pellets
30, such as those composed of armor-grade alumina, another
appropriate ceramic, or ultra high hardness steel. This layer may
be constructed according to any one of a plethora of arrangements
which are well known in the art and have an appropriate thickness
for protection against armor piercing projectiles.
[0022] The inner liner 20 may be made from a composite laminate
such as aramid, E-glass or S-glass fiberglass, high density
polyethylene, or a hybrid thereof. This layer is attached to the
inner side of the base layer 16, for example by gluing or bolting,
as appropriate.
[0023] The add-on and base layers are adapted to absorb and
dissipate kinetic energy of armor piercing projectiles and of FSPs,
or residual fragments of improvised explosive devices, which will
perforate the auxiliary layer 12, mainly due to the deformation and
shattering thereof. The inner liner 20 is designed absorb remaining
kinetic energy of, and to stop, any residual fragments which may
pass the base layer.
[0024] The auxiliary layer 12 is made from a relatively soft
ductile material, such as aluminum. The auxiliary layer 12 may be
made from any material which experiences local deformation due to a
ductile failure mode, as described in "Dynamic Perforation of
Viscoplastic Plates by Rigid Projectiles" (M. Ravid & S. R.
Bodner, International Journal of Engineering Science, Vol. 21, No.
6, pp 577-591, 1983) and "Penetration into Thick
Targets--Redefinement of a 2D Dynamic Plasicity Approach" (M. Ravid
& S. R. Bodner, International Journal of to Impact Engineering,
Vol. 15. No. 4, pp 491-499, 1994), whose contents are incorporated
herein by reference. As explained in the above articles, when
material of the kind of which the auxiliary layer is made, is
perforated by a projectile, the material's deformation during such
perforation includes the stages of dynamic plastic penetration,
bulge formation and bulge advancement stage at the end of which the
projectile exists so that the exit lips at the rear surface of the
material usually do not shear out. This leads to the material of
the auxiliary layer being locally deformed at a plurality of
locations upon its perforation by a plurality of FSPs, whereby
multi-hit capability of the armor is ensured.
[0025] Additionally, the material has an elongation of greater than
8 percent, a yield strength not greater than 52 kg.sub.f/mm.sup.2,
and a Brinell hardness not be greater than 165
kg.sub.f/mm.sup.2.
[0026] In operation, FSPs such as the FSP 24 which are typically
between 0.3'' and 20 mm in diameter, and which travel at a high
initial velocity, e.g., up to a first velocity of about 1500 m/s,
pierce the auxiliary layer 12 in a plurality of separate locations,
whereby a substantial portion of the kinetic energy of the FSPs is
mitigated and their velocity is reduced to a second velocity within
the range against which the main armor layer 14 can provide
protection against the slowed down FSPs. The auxiliary layer 12 may
also alter the trajectory and stability of the armor piercing
projectiles so that they develops a yaw angle, which reduces their
penetration capability. This effect is more pronounced in a case of
oblique impacts of the armor piercing projectiles on the armor 10.
In general, although armor piercing projectiles such as the APP 26,
may also loose part of their kinetic energy when penetrating the
auxiliary layer 12, this does not have to be the case since the
main armor layer 14 may be adapted to protect against armor
piercing projectiles without their previous energy absorption
provided by the auxiliary layer 12.
[0027] In ballistic tests, different ballistic armors, each
according to the present invention, were successfully tested
against both FSPs and small caliber armor piercing projectiles at
different velocities. All of the armors comprised auxiliary layers
made of the same commercial aluminum alloy but having different
thickness and base layers made of steel having different hardness
and thickness. Some armors comprised an add-on ceramic layer made
of cylindrical pellets held together by a thermoplastic or
thermoset binder, the pellets being made of alumina
(Al.sub.2O.sub.3 98%), and having diameter 12.7 mm, and height 8
mm, and having domed front ends. Some of the armors comprised inner
liner made of aramid and fiberglass. The test particulars are
summarized in the table below.
TABLE-US-00001 TABLE 1 Multi-Functional Armor Test Parameters Main
Armor Layer Inner Auxiliary Base Protective Layer Stand off Add-On
Layer Layer Liner Projectile Velocity 15 mm Al 0 to -- 10 mm 15 mm
20 mm FSP 1100 m/s 6061-T651 100 mm HHS Aramid and 7.62 .times. 54
mm API 830 m/s (42 kg/m.sup.2) Fiberglass B-32 16 mm Al 0 Ceramic
layer (32 kg/m.sup.2) 10 mm -- 20 mm FSP 1200 m/s 6061-T651 with
fiberglass backing HHS 7.62 .times. 51 mm AP 950 m/s (44
kg/m.sup.2) FFV 16 mm Al 0 Ceramic layer (32 kg/m.sup.2) 10 mm 10
mm 20 mm FSP 1280 m/s 6061-T651 HHS Aramid and 7.62 .times. 51 mm
AP 960 m/s (44 kg/m.sup.2) Fiberglass FFV 1/4'' AL 0 to -- 5.5 mm
15 mm 0.5'' FSP 1067 m/s 6061-T651 10 mm UHH Aramid and 7.62
.times. 54 mm LPS 866 m/s (17 kg/m.sup.2) Fiberglass HHS = High
hardness steel (Armor type) UHH = Ultra high hardness (Armor
steel)
[0028] Those skilled in the art to which this invention pertains
will readily appreciate that numerous changes, variations and
modifications can be made without departing from the scope of the
invention mutatis mutandis.
* * * * *