U.S. patent application number 14/110452 was filed with the patent office on 2014-02-20 for protective armour element.
This patent application is currently assigned to Nederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek TNO. The applicant listed for this patent is Johannes Pieter Frans Broos, Erik Peter Carton. Invention is credited to Johannes Pieter Frans Broos, Erik Peter Carton.
Application Number | 20140047972 14/110452 |
Document ID | / |
Family ID | 44544058 |
Filed Date | 2014-02-20 |
United States Patent
Application |
20140047972 |
Kind Code |
A1 |
Carton; Erik Peter ; et
al. |
February 20, 2014 |
PROTECTIVE ARMOUR ELEMENT
Abstract
The invention is directed to a protective amour element (2), to
body armour comprising one or more of such elements, and to a
preventive method of reducing behind amour blunt trauma of an
individual. The protective armour element (2) of the invention
comprises a fabric and/or a fibre based composite, wherein said
amour element, prior to impact of a projectile, has a concave
strike face.
Inventors: |
Carton; Erik Peter; (Delft,
NL) ; Broos; Johannes Pieter Frans; (Delft,
NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carton; Erik Peter
Broos; Johannes Pieter Frans |
Delft
Delft |
|
NL
NL |
|
|
Assignee: |
Nederlandse Organisatie voor
toegepast-natuurwetenschappelijk onderzoek TNO
Delft
NL
|
Family ID: |
44544058 |
Appl. No.: |
14/110452 |
Filed: |
April 19, 2012 |
PCT Filed: |
April 19, 2012 |
PCT NO: |
PCT/NL2012/050256 |
371 Date: |
October 29, 2013 |
Current U.S.
Class: |
89/36.02 |
Current CPC
Class: |
F41H 1/02 20130101; F41H
5/0428 20130101; F41H 5/0421 20130101; F41H 1/04 20130101; F41H
5/0471 20130101; F41H 1/00 20130101; F41H 5/04 20130101 |
Class at
Publication: |
89/36.02 |
International
Class: |
F41H 5/04 20060101
F41H005/04; F41H 1/00 20060101 F41H001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 20, 2011 |
EP |
11163240.2 |
Claims
1. A protective armour element comprising a fabric and/or a fibre
based composite, wherein said armour element, prior to impact of a
projectile, has a concave strike face.
2. The protective armour element according to claim 1, wherein said
element comprises a reinforced fibre material.
3. The protective armour element according to claim 1, wherein said
protective armour element comprises at least one selected from the
group consisting of ultrahigh molecular weight polyethylenes,
polyamides (including aromatic polyamides such as
poly(paraphenylene terephthalamide), poly(metaphenylene
isophthalamide and poly(metaphenylene terephthalamide)),
poly(p-phenylene 2,6 benzobisoxazole) and combinations thereof.
4. The protective armour element according to claim 1, wherein said
protective armour element consists of polymer fabric and/or polymer
fibre based composite.
5. The protective armour element according to claim 1, wherein the
concave strike face of the armour element has a radius of curvature
that is at least 20% greater than the average thickness of the
armour.
6. The protective armour element according to claim 1, having an
equivalent circular diameter in the range of 1-100 cm.
7. An armour system, comprising a ceramic and/or metal strike face
and at least one protective armour elements according to claim 1 as
a backing for said ceramic or metal strike face.
8. A body armour comprising at least one protective armour elements
according to claim 1.
9. The body armour according to claim 8, further comprising at a
body face of the armour and opposite the concave strike face, an
anti trauma liner.
10. The body armour according to claim 9, wherein said anti trauma
liner comprises foam material.
11. The body armour according to claim 8 in the form of a helmet,
an insert for a vest, or a side protection plate.
12. The body armour according to claim 8, further comprising at
least one material selected from the group consisting of ceramic
material, metallic material, and composite material.
13. The body armour according to claim 8, comprising a plurality of
protective armour elements, while the overall strike face of the
body armour is convex.
14. A method of preventing or reducing behind armour blunt trauma
of an individual comprising protecting said individual with body
armour according to claim 1.
15. The protective armour element according to claim 5 wherein the
concave strike face of the armour element has a radius of curvature
that is one of at least 50% greater, at least 100% greater, at
least 200% greater, at least 300% greater, at least 400% greater,
at least 500% greater, at least 1000% greater, or at least 2000%
greater than the thickness of the armour.
16. The protective armour element according to claim 6 having an
equivalent circular diameter in the range of 1-50 cm.
17. The protective armour element according to claim 6 having an
equivalent circular diameter in the range selected from 2 cm-40 cm,
2 cm-25 cm, or 3 cm-10 cm.
18. The body armour according to claim 13, comprising at least 5,
or at least 10, or at least 20 protective armour elements, while
the overall strike face of the body armour is convex.
Description
[0001] The invention is directed to a protective armour element, to
body armour comprising one or more of such elements, and to a
method of preventing or reducing behind armour blunt trauma of an
individual. More in particular, the invention relates to a
protective armour element suitable for use in armour that is
intended to withstand and provide protection against blunt trauma
or ballistic impact from a projectile or the like.
[0002] In law enforcement and military environments it is often
necessary and appropriate to use protective shields of various
forms and configurations to protect personnel and equipment from
injury or mechanical damage caused by projectiles including
bullets, spall, shrapnel, etc. The protective shield may be of a
type that is worn as protective personnel body armour. For such
applications it is desirable that the protective shield is strong,
light, and thin, and capable of dispersing or otherwise dealing
with body heat and perspiration.
[0003] Body armour comprising metal and ceramic inserts is
well-known. Nevertheless, in order to provide sufficient protection
against the incoming energy of large fragments or high velocity
bullets the inserts are relatively heavy and uncomfortable. Because
of the weight, such body armour may be discarded and the respective
person is left unprotected. Yet another disadvantage of this body
armour is the fact that the metal and ceramic inserts merely
deflect the projectile. It is not unusual for a wearer to survive
the initial impact only to receive substantial and even life
threatening injury as the deflected material strikes another part
of his body.
[0004] In an attempt to provide light-weight alternatives,
fibre-based body armour has been developed. Such body armour
typically comprises polymer fabric and/or polymer fibre-based
composites. In particular flexible aramid (aromatic amide) fibres
have proven to be effective, for instance in bullet-proof vests for
police forces and private security guards.
[0005] In contrast to the body armour comprising metal and ceramic
inserts, fibre-based body armour does not protect the wearer by
deflecting projectiles. Instead, the layers of high tensile
strength material forming the body armour are intended to catch the
projectile and spread its force over a larger portion of the
wearer's body, and bring the projectile to a stop before it can
penetrate into the body. This tends to deform soft-core projectile,
further reducing its ability to penetrate. However, while body
armour can prevent invasive bullet wounds, the wearer's body at
least will follow the back-face deflection on the armour, and can
often incur blunt force trauma.
[0006] In order to provide extra protection to vital areas, hard
plate inserts of polymer-fibre based composites can be prepared.
Such plate carrying body armour provides additional protection.
[0007] In the last few decades, several new fibres and construction
methods for body armour have been developed including woven
Dyneema.TM. (an ultrahigh molecular weight polyethylene fibre
obtainable from DSM), GoldFlex.TM. (a roll product consisting of
four plies of unidirectional aramid fiber, crossplied at
0.degree./90.degree./0.degree./90.degree., and sandwiched in a
thermoplastic film obtainable from Honeywell), Spectra.TM. (an
ultrahigh molecular weight polyethylene fibre obtainable from
Honeywell), Twaron.TM. (a poly(p-phenylene terephthalamide) fibre
obtainable from Teijin Aramid), Zylon.TM. (a
poly(p-phenylene-2,6-benzobisoxazole) fibre obtainble from Toyobo),
Kevlar.TM. (a poly(p-phenylene terephthalamide) fibre obtainable
from DuPont, and Nomex.TM. (a poly(m-phenylene terephthalamide)
fibre obtainable from DuPont). Although Kevlar.TM. has long been
used, some of the newer materials are said to be lighter, thinner
and more resistant than Kevlar.TM., but are considerably more
expensive. But even so, the expense is justified because the more
lightweight, thin and less insulating a protective ballistic
resistant garment is made, the more likely an intended user (such
as military personnel) will actually wear the garment, especially
in the case of hostile environmental conditions and long working
shifts.
[0008] There is a continuing need to provide improved armour
materials that are thin and lightweight, have the ability to
capture rather than reflect projectiles, bullet spall and the like,
and in the case of body armour reduce blunt trauma injuries.
[0009] When a projectile strikes fibre-based body armour, the
impact load causes a bulge to develop which deforms the back
surface of the armour. Since the armour is worn adjacent to the
body, this bulge or "deformation" can extend into the body of the
wearer. If the deformation or deformation rate is large, tissue
damage or trauma may occur. It is widely accepted that trauma
resulting from back face signature (BFS) can be severe and
debilitating. Hence, while the body armour stops penetration of the
projectile, it allows its impulse to be transferred through the
armour system directly to the body of the wearer as to cause
injuries to the bone structure and internal organs. Possible
medical consequences include extravasations of blood, termination
of respiration, lung damage, reduced oxygen pressure in the blood
(possibly leading to coma or even death). This injury is typically
described as "blunt trauma", which is correlated to the extent of
inward deformation suffered by the armour as it is impacted by a
projectile.
[0010] WO-A-2011/005 274 discloses armour having a strike face that
is outwardly convex or concave or exhibits both concave and convex
surface portions. The strike face sheet preferably comprises
titanium, a titanium alloy, aluminium, an aluminium alloy; an
organic-matrix composite material, such as, for example,
graphite-carbon- or fibreglass-reinforced epoxy composite material,
a laminated material, such as titanium/aluminium laminate. The
document does not disclose a protective armour element comprising a
fabric and/or a fibre based composite in combination with a concave
strike face. EP-A-2 180 286 discloses a ballistic collar which is
arranged to surround a human's neck, comprising a harmonica shaped
member. The member is preferably formed by a plurality of plied
sheets, preferably made of a ballistic rated body armour fabric
comprising strong synthetic fibres. The strike surface is not
concave and not inwardly curved.
[0011] U.S. Pat. No. 3,398,406 discloses a body armour comprising
horizontally extending ribs. The ribs are horizontally and
vertically convex and the strike face is composed of a plurality of
double convex elements.
[0012] Objective of the invention is to overcome at least part of
the disadvantages of the prior art by providing a fibre-based
protective armour element that exhibits reduced deformation upon
impact of a projectile.
[0013] Further objective of the invention is to provide a
fibre-based body armour that reduces the wearer's risk of suffering
from behind armour blunt trauma.
[0014] The inventors surprisingly found that the deformation of
fibre-based protective elements is less when the strike face of the
element has a specific form.
[0015] Accordingly, in a first aspect, the invention is directed to
a protective armour element comprising a fabric and/or a fibre
based composite, wherein said armour element, prior to impact of a
projectile, has a concave strike face.
[0016] The inventors surprisingly found that the protective armour
element of the invention has significantly less deformation upon
impact of a projectile. Due to the use of fabric, the protective
armour of the invention is advantageously light weight.
Accordingly, body armour comprising protective armour elements as
defined herein have a reduced risk of giving rise to behind armour
blunt trauma.
[0017] Especially for body armour, it is conventional to provide
armour having a convex strike face, so that the armour can locally
follow the curvature of the human body as much as possible. For
metal or ceramics materials this is not very relevant because these
materials do not strongly deform in the direction of the body. The
inventors realised that this is different for protective armour
elements on the basis of fabric and/or fibre based composite. Since
these fibre materials result in a much larger deformation in the
direction of the body upon impact of the projectile, the shape of
the protective armour element is much more relevant. Surprisingly,
the inventors found that even though such armour elements
conventionally have a convex strike face in view of the object or
individual to be protected, the actual deformation upon impact is
much smaller when the armour element has a concave strike face.
[0018] Without wishing to be bound by theory, the inventors believe
that armour based on fabric and/or fibre based composite is only
effective if the fibres are subject to an axial tensile stress. Due
to the concave (or even flat) starting shape of the protective
armour elements a large deformation is required in order to provide
the fibres with sufficient tensile stress. This is because the
convex shape should first locally be turned over to a concave
shape, during which the fibres are not subject to more tensile
stress than in the starting situation. On the other hand, impact of
a projectile on a protective armour element having a concave strike
face immediately leads to a significant increase in tensile stress
of the fibres and, as a result, to a smaller deformation of the
protective armour element.
[0019] The term "armour" as used in this application is meant to
refer to materials that are resistant to forces applied to the
armour to penetrate the armour such as projectiles and the
like.
[0020] The term "concave" as used in this application is meant to
refer to a surface that is curving inward as opposed to convex. It
is understood that the concave is not restricted to describing a
surface with a constant radius of curvature, but rather is used to
denote the general appearance of the surface. In addition, it is
understood that multiple concave elements can still form an overall
convex surface as will be explained herein below.
[0021] The concave strike face of the armour element can have a
radius of curvature that is greater than the thickness of the
armour, such as 20% greater than the thickness of the armour, 50%
greater, 100% greater, 200%, 300%, 400%, 500%, 1000%, 2000%, or
even greater. The radius of curvature of the strike face of the
armour element must be smaller than infinity, otherwise the strike
face is not concave.
[0022] Preferably, the size of the armour element can vary widely.
It is preferred that the size of the armour element is larger than
the projectile against which the armour is supposed to provide
protection. Hence, the armour element can have an equivalent
circular diameter (defined as the diameter of a circle that has the
same area as the armour element) ranging from 1-100 cm, preferably
1-50 cm, such as 2-40 cm, 2-25 cm, or 3-10 cm.
[0023] In a preferred embodiment, the protective armour element
comprises a reinforced fibre material. The reinforced fibre
material can comprise a multi-layer of weaves and a composite
thereof with a matrix. Suitably, the reinforced fibre material can
comprise polymer fibres, but also carbon fibres, glass fibres, and
the like may be employed. It is however, preferred, that the
reinforced fibre material comprises a polymer fibre. The fibres in
the reinforced fibre material may be embedded in a polymer matrix,
such as an epoxy, vinyl ester or polyester thermosetting
plastic.
[0024] Suitably, the protective armour element comprises one or
more from the group consisting of ultrahigh molecular weight
polyethylenes, polyamides (including aromatic polyamides such as
poly(paraphenylene terephthalamide), poly(metaphenylene
isophthalamide and poly(metaphenylene terephthalamide)),
poly(p-phenylene-2,6-benzobisoxazole). Examples of these materials
are commercially available under the trademarks Dyneema.TM.
GoldFlex.TM., Spectra.TM., Twaron.TM., Zylon.TM., Kevlar.TM.,
Nomex.TM., and the like.
[0025] The protective armour element comprises a fabric and/or a
fibre-based composite. In an embodiment, the protective armour
element consists of fabric and/or fibre-based composite.
Preferably, the fabric is a polymer fabric and/or the fibre-based
composite is a polymer fibre-based composite. Polymer fabric
protective armour elements can provide protection against shrapnel
and so-called soft-core ammunition (typically ammunition fired from
rifles). A polymer fibre-based composite can provide additional
protection, such as against armour piercing bullets using a hard
metal or ceramic strike-face.
[0026] Therefore, in a further aspect the invention is directed to
an armour system, comprising a ceramic or metal strike face and one
or more protective armour elements according to the invention as a
backing for said ceramic or metal strike face.
[0027] The present invention is especially advantageous when
applied in body armour. Accordingly, in a further aspect the
invention is directed to body armour comprising one or more
protective armour element as defined herein.
[0028] The body armour of the invention can comprise at the body
face of the armour and opposite the concave strike face, an
anti-trauma liner. Such liners are well-known in the art.
Typically, such anti-trauma liners comprise foam material.
Anti-trauma liners help to reduce the indent of the human body by
facilitating the first phase of back-face deformation of the armour
were the acceleration and maximal velocity are highest. The human
body only experiences the latest phase of the deflection at which
both the acceleration and maximal velocity are considerably
reduced.
[0029] Suitably, the body armour of the invention can be in the
form of a helmet, an insert for a vest, and side-protection
plate.
[0030] The protective armour element comprises a fabric and/or a
fibre based composite. The fabric comprises fibre and/or is fibre
based, preferably glass, carbon and/or polymer fibre. The fibre
based composite is preferably based on glass, carbon and/or polymer
fibre. A fabric and/or a fabric based composite comprising polymer
fibres is preferred.
[0031] The fibres are preferably applied in such a way that an
inward distortion of the armour element results in axial tensile
stress of the fibres. Suitably, the fibres are woven. Suitably, the
fibres are applied in a direction along the inward curve of the
armour element strike face. In this way, the fibres extend at least
in part in the inward direction. The fibres are preferably applied
in a direction in which the strike face is concave.
[0032] The body armour preferably comprises a plurality of armour
elements. The armour elements are preferably arranged in such a
way, that the concave strike area of the armour elements of the
body armour is 50% or more, more preferably 75% or more, up to 99%
or more, up to close to, but smaller than, 100% of the total strike
face area of the body armour.
[0033] The body armour preferably comprises a plurality of concave
armour elements, such as 5 or more, preferably 10 or more, more
preferably 20 or more armour elements (such as 20-50 armour
elements), while the overall strike face of the armour is convex.
For example, such armour could have an arrangement of armour
elements as in a golf ball. A golf ball has the overall convex
shape of a sphere, while the dimples are concave.
[0034] The armour elements comprise a recess in the strike face of
the armour. The recess has a shape in the plane of the strike face
when viewed from the top that can be a circle, as for example in
FIG. 2A, or a square, rectangle, triangle, hexagon, or another
shape. An armour may comprise armour elements with various shapes
and sizes. When the armour elements have recesses with circular
shape, as in FIG. 2A, some gaps present between the armour elements
as circles are not tessellating. Preferably, the armour elements
are arranged in pattern wherein the space between the armour
elements is minimal, such as in a tessellating pattern. For circles
and hexagons, a hexagonal lattice arrangement or honeycomb pattern
is preferred.
[0035] The recess in the strike face has a depth d, measured as the
maximum depth of the recess relative to a tangent line x over the
strike face, as shown in FIG. 2B. The depth d may be smaller, equal
or larger than the equivalent circular diameter (A). Preferably,
the depth is 0.1A-1A, more preferably 0.20-0.80 A, even more
preferably 0.3-0.7 A.
[0036] The armour has an average thickness t, excluding the
recesses of the armour element (t in FIG. 2B). The recess of an
armour element has preferably a depth d of 0.05-0.95 t, more
preferably 0.05-0.5 t, even more preferably 0.05-0.25 t. The depth
d of the recess may even be larger than the thickness, if the inner
surface of the armour follows the strike face. An inner surface
that is essentially conformal to the strike face follows the strike
face. In FIG. 3, an example is shown of a armour with an inner
surface 32 that follows strike face 31. In case the armour has an
inner surface that follows the strike face, or is essentially
conformal to the strike face, the thickness t is preferably 0.1-2
d, more preferably 0.5-1.5 d, even more preferably 0.75-1.5 d, most
preferably 0.9-1.3 d.
[0037] The inside face of a body armour is preferably conformal to
the body, the inside face of a helmet is preferably conformal to a
head. The armour elements may be comprised in a helmet and the body
armour may be a helmet.
[0038] Suitably, the armour element is reinforced, at least in
part, at the strike face parts not comprised in an armour element
with concave strike face and or close to the outward end of the
armour elements. For example, in FIG. 3 the armour is reinforced at
position 33.
[0039] Examples of a front insert plate and a back insert plate in
accordance to the invention are shown in FIG. 1. FIG. 1A is a
cross-section of a vest (1), with a front insert plate and back
insert plate (4). The insert plate comprises multiple concave
protective armour elements (2). The insert plate further comprises
an anti-trauma liner foam (3). Back insert plate (4) is similar in
design as front insert plate (2). FIG. 1B is a front view of the
insert plate just showing the multiple concave protective armour
elements (2).
[0040] An example of a helmet in accordance with the invention is
shown in FIG. 2. FIG. 2A is a top view of the helmet showing the
multiple concave protective armour elements (2). FIG. 2B shows a
cross-section of a helmet that does not have an anti-trauma liner,
while the helmet of FIG. 2C comprises, apart from the multiple
concave protective armour elements, an anti-trauma liner (3). The
helmet shown in FIG. 2 has an overall convex strike face that is
built up from multiple protective armour elements having a concave
shape.
[0041] The invention will now be further elucidated by the
following Examples, which are not intended to limit the invention
in any way.
EXAMPLES
[0042] Experiments were performed to test the difference in clay
indent of an armour element upon impact of a projectile when the
armour element has a concave striking face or a convex striking
face.
Example 1
Helmet
[0043] In this example, 9 mm FMJ bullets were shot at a speed of
about 400 m/s on 7 mm thick Dyneema.TM. helmets. The non-striking
face of the helmet was either in contact with clay or a small air
gap was maintained between the helmet and the clay. After impact
the level of indent was determined by measuring the depth of the
crater in the clay. The shots were either fired with the convex
side of the helmet as striking face, or with the concave side of
the helmet as striking face. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Air gap Bullet speed Clay crater depth
Striking face [mm] [m/s] [mm] convex 0 426 35 concave 0 358 16
convex 18 424 26 concave 18 420 0
Example 2
Body Insert-Plate
[0044] In this example, 7.62.times.51 Ball ammunition was shot at a
speed of about 840 m/s on 20 mm thick Dyneema.TM. body inserts. The
non-striking face of the body insert was either in contact with
clay or a small air gap was maintained between the body insert and
the clay. After impact the level of indent was determined by
measuring the depth of the crater in the clay. The shots were
either fired with the convex side of the body insert as striking
face, or with the concave side of the body insert as striking face.
The results are shown in Table 2.
TABLE-US-00002 TABLE 2 Air gap Bullet speed Clay crater depth
Striking face [mm] [m/s] [mm] convex 0 826 64 concave 0 836 44
convex 17 846 45 concave 17 850 30
* * * * *