U.S. patent application number 13/061582 was filed with the patent office on 2011-09-08 for composite auxetic armour.
This patent application is currently assigned to GLOBAL COMPOSITES GROUP LIMITED. Invention is credited to David Skertchly.
Application Number | 20110214560 13/061582 |
Document ID | / |
Family ID | 39866219 |
Filed Date | 2011-09-08 |
United States Patent
Application |
20110214560 |
Kind Code |
A1 |
Skertchly; David |
September 8, 2011 |
COMPOSITE AUXETIC ARMOUR
Abstract
A ceramic amour plate (1,41,50,70) having auxetic reinforcement
(2,40,51,71). The auxetic reinforcement may be provided utilising
auxetic fibres, auxetic knits or weaves, or lay-ups exhibiting
auxetic behaviour. The auxetic reinforcement reduces cracking of
the ceramic plate to improve multi-hit performance. The
reinforcement may be provided as a layer (2,40, 51) bonded to the
surface of the ceramic plate (1,41,50) or as an integral part (71)
of the ceramic plate (70).
Inventors: |
Skertchly; David;
(Southhamptom Hampshire, GB) |
Assignee: |
GLOBAL COMPOSITES GROUP
LIMITED
Buckinghamshire
GB
|
Family ID: |
39866219 |
Appl. No.: |
13/061582 |
Filed: |
August 24, 2009 |
PCT Filed: |
August 24, 2009 |
PCT NO: |
PCT/GB2009/051049 |
371 Date: |
May 26, 2011 |
Current U.S.
Class: |
89/36.02 ;
89/903; 89/904; 89/906; 89/914; 89/917; 89/922 |
Current CPC
Class: |
F41H 5/0428 20130101;
F41H 5/0414 20130101 |
Class at
Publication: |
89/36.02 ;
89/903; 89/904; 89/906; 89/917; 89/914; 89/922 |
International
Class: |
F41H 5/04 20060101
F41H005/04; F41H 5/08 20060101 F41H005/08; F41H 1/02 20060101
F41H001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 4, 2008 |
GB |
0816083.0 |
Claims
1. An armour plate, comprising: at least one ceramic plate; and a
component which exhibits auxetic behaviour.
2. An armour plate according to claim 1 wherein the ceramic plate
comprises the component which exhibits auxetic behaviour.
3. An armour plate according to claim 1 wherein the component which
exhibits auxetic behaviour is comprised in a composite layer on a
surface of the ceramic plate.
4. An armour plate according to claim 3 wherein the composite layer
is formed on the surface during curing of the composite layer.
5. An armour plate according to claim 3, wherein the composite
layer is bonded to the surface by an adhesive.
6. An armour plate according to claim 3. wherein a composite layer
is formed on each surface of the ceramic plate.
7. An armour plate according to claim 1 wherein the component
exhibiting auxetic behaviour is at least one auxetic fibre.
8. An armour plate according to claim 1 wherein the component
exhibiting auxetic behaviour is a knitted or woven fabric.
9. An armour plate according to claim 8 wherein the fabric is
formed of non-auxetic fibres.
10. An armour panel comprising two or more armour plates separated
by a composite structure, wherein the two or more armour plates
each comprise at least one ceramic plate and a component which
exhibits auxetic behaviour.
11. (canceled)
12. An item of armoured clothing comprising: a piece of clothing
associated with at least one armour plate, wherein the at least one
armour plate comprises at least one ceramic plate and a component
which exhibits auxetic behaviour.
13. An item of armoured clothing according to claim 12, comprising
two or more armour plates separated by a composite structure.
Description
BACKGROUND
[0001] This invention relates to improvements in armour and in
particular to the improvement of ceramic armour using auxetic
materials.
[0002] The use of ceramic materials such as Aluminium oxide, so
called high alumina ceramics, and Silicon carbide as armour is well
known. The material is formed into plates to defend a person or
object from impacts such as bullets or shrapnel. For example,
plates may be formed into body armour for use in garments to
protect people, or may be located on the outside of vehicles to
protect that vehicle.
[0003] When a bullet or other item strikes the ceramic material the
impact causes the bullet to fragment. The fragments may then be
stopped either within the ceramic or by a spall liner before they
harm the person or object being protected.
[0004] When a ceramic plate is struck by a projectile the plate
typically cracks and shatters due to the impact. Locally this
shattering/cracking absorbs some of the energy of the projectile,
however once cracked the plate is less able to protect against
further strikes and thus its effectiveness is significantly, or
totally, reduced.
[0005] Ceramic armour having improved multi-hit capability is
therefore desirable.
SUMMARY
[0006] The following presents a simplified summary of the
disclosure in order to provide a basic understanding to the reader.
This summary is not an extensive overview of the disclosure and it
does not identify key/critical elements of the invention or
delineate the scope of the invention. Its sole purpose is to
present some concepts disclosed herein in a simplified form as a
prelude to the more detailed description that is presented
later.
[0007] There is provided an armour plate, comprising at least one
ceramic plate, and a component which exhibits auxetic
behaviour.
[0008] The ceramic plate may comprise the component which exhibits
auxetic behaviour.
[0009] The component which exhibits auxetic behaviour may be
comprised in a composite layer on a surface of the ceramic
plate.
[0010] The composite layer may be formed on the surface during
curing of the composite layer.
[0011] The composite layer may be bonded to the surface by an
adhesive.
[0012] A composite layer may be formed on each surface of the
ceramic plate.
[0013] The component exhibiting auxetic behaviour may be at least
one auxetic fibre.
[0014] The component exhibiting auxetic behaviour may be a knitted
or woven fabric.
[0015] The fabric may be formed of non-auxetic fibres.
[0016] There is also provided an armour panel comprising two or
more armour plates as described herein separated by a composite
structure.
[0017] There is also provided an item of armoured clothing
comprising an armour plate or panel as described herein.
DESCRIPTION OF THE DRAWINGS
[0018] Embodiments of the present invention will now be further
described, by way of example, with reference to the figures,
wherein:
[0019] FIG. 1 shows a cross-section of a structure according to an
embodiment of the invention;
[0020] FIGS. 2 and 3 are flow-charts of methods of manufacturing an
embodiment of the invention;
[0021] FIGS. 4 and 5 show cross-sections of structures according to
embodiments of the invention;
[0022] FIG. 6 is a flow-chart of a method of manufacturing an
embodiment of the invention;
[0023] FIG. 7 shows a cross-section of a structure according to an
embodiment of the invention; and
[0024] FIG. 8 is a flow-chart of a method of manufacturing the
embodiment shown in FIG. 7.
DETAILED DESCRIPTION
[0025] The detailed description provided below in connection with
the appended drawings is intended as a description of the present
examples and is not intended to represent the only forms in which
the present example may be constructed or utilized. The description
sets forth the functions of the example and the sequence of steps
for constructing and operating the example. However, the same or
equivalent functions and sequences may be accomplished by different
examples.
[0026] FIG. 1 shows a cross-section of a composite structure
according to an embodiment of the current invention.
[0027] Reinforcement layers 2 are bonded to a ceramic plate 1 and
spall liner 3 is an optional layer applied to the back surface of
the structure. Reinforcement layers 2 comprise a composite material
incorporating an auxetic component. The auxetic nature of the
reinforcement reduces the propagation of cracks in the ceramic
plate when it is struck by a projectile. This limits the area of
damage to the locality of the impact, thereby improving the
multi-hit capability of the armour.
[0028] Auxetic materials have a negative Poisson's ratio and thus
when a tensile stress is applied to an auxetic structure, its size
in a direction perpendicular to the applied stress increases (in
contrast to conventional materials whose size reduces when a
tensile stress is applied).
[0029] Reinforcement layers 2 are intimately bonded to the ceramic
plate such that the layers are mechanically bound together. When a
projectile strikes the armour, and hence the ceramic plate, the
consequent deformation of the plate is transferred to the
reinforcement layer. The deformation causes tensile stresses in the
auxetic component which expands in a direction perpendicular to the
stress. That expansion resists the propagation of cracks in the
ceramic plate, and thus the amount of cracking that occurs for a
particular projectile strike is reduced.
[0030] The reduction in crack propagation results in the structural
integrity of the plate after a strike being improved and therefore
the multi-hit capability may be improved compared to prior-art
armours of comparable materials. The addition of a composite layer
having auxetic reinforcement may therefore improve the performance
of ceramic armour.
[0031] The auxetic component may be in the form of auxetic fibres
included in place of, or in addition to, conventional reinforcement
fibres. For example, the composite layer may be a conventional
fibre-glass/epoxy resin composite, with additional auxetic fibres.
Alternatively the composite layer may utilise only auxetic fibres
in a suitable matrix. PCT publication number WO2000/053830
discloses a manufacturing technique for auxetic fibres.
[0032] The auxetic component may also be a knitted structure having
auxetic behaviour (see for example PCT publication number
WO2008/016690), or an auxetic woven fabric (see for example
European publication number EP1786962).
[0033] The auxetic component may be provided by a uni-directional
lay-up of auxetic or non-auxetic fibres. It has been shown that
auxetic behaviour can be obtained with certain fibre orientations,
even if the fibres themselves are non-auxetic (see phys. Stat. sol.
(b) 244, No. 3, 883-892 (2007, E. H. Harkati, A. Bezazi, F. Scarpa,
K. Alderson and A. Alderson).
[0034] FIG. 2 shows a flow-chart of a method of manufacture of the
structure shown in FIG. 1.
[0035] At step 200 reinforcement fibres are pre-impregnated with a
suitable matrix material. The reinforcement includes the auxetic
component in one of the forms described above. At step 201 the
layer is placed in a mould and at step 202 a ceramic plate is
placed over the reinforcement layer. At step 203 a further
reinforcement layer incorporating an auxetic reinforcement and
suitable matrix is placed on the ceramic plate. At step 204 the
structure is cured in an appropriate fashion determined by the
materials and structure utilised. For example, a vacuum bag may be
applied around the structure, and cure maybe performed at a
pressure and temperature of 90 psi and 135.degree. C. for 1
hour.
[0036] At step 205 the structure is removed from the curing process
and at step 206 a spall liner may be applied if required.
[0037] The resulting structure is a ceramic plate with a
reinforcement layer incorporating an auxetic component bonded to
each surface. As will be appreciated, this method, with suitable
modification, is also applicable to the manufacture of a plate with
reinforcement on only one surface.
[0038] FIG. 3 shows a flow chart of an alternative method of
manufacturing the structure shown in FIG. 1.
[0039] At step 300 reinforcement fibres, for example glass fibres,
are mixed with thermoplastic strands (for example polypropylene).
As described above, the auxetic effect may be provided by the use
of auxetic fibres, an auxetic knit/weave or an auxetic lay-up. If
auxetic fibres are utilised these may be provided as a proportion
of the thermoplastic strands, but the material of the auxetic
strands must be selected such that they are not affected by the
curing process used to melt the strands which will form the matrix.
At step 301 the layer is placed in a mould and at step 302 a
ceramic tile is placed over the layer. At step 303 a further layer
of mixed fibres and strands is placed over the tile and at step 304
the structure is cured in an appropriate fashion determined by the
materials and structures utilised. For example, a vacuum bag may be
applied around the structure and cure may be performed at a
pressure and temperature of 90 psi and greater than 185.degree. C.
respectively for 1 hour.
[0040] At step 305 the structure is removed from the curing process
and at step 306 a spall liner may be applied if required.
[0041] FIG. 4 shows a cross-section of a composite structure
according to an embodiment of the invention.
[0042] In the structure shown in FIG. 4 reinforcement layers 40
incorporating an auxetic component are bonded to a ceramic plate 41
using an adhesive 42. The structure shown in FIG. 4 may be formed
by producing the reinforcement layers 40 using known techniques and
subsequently bonding them to the surfaces of the ceramic plate 41.
The reinforcement layers may be bonded using any suitable adhesive,
for example a 2-part epoxy. The structure may also be manufactured
by co-curing the reinforcement layers 40 and adhesive 42, which may
be a more efficient method of production. The reinforcement layers
may utilise any of the structures described above.
[0043] The spall liner 43 may be bonded to the second reinforcement
layer using adhesive.
[0044] FIG. 5 shows a cross-section of a multi-layer armour
according to an embodiment of the invention.
[0045] Two ceramic plates 50 with an auxetic reinforcing component
51 are formed around a composite structure 52. Multiple layers of
ceramic material 50 may have performance advantages in certain
situations, for example in resisting blast impacts, and may also
have advantages in manufacturing. The composite structure 51 may be
structural elements such as beams or honeycomb, or may be fillers
such as fibres with auxetic or non auxetic properties.
[0046] Each reinforcement layer 51 includes an auxetic component as
described previously. The auxetic component may be provided
throughout each reinforcement layer, or may be provided in only
selected plies of those layers, for example only in the ply
adjacent to the ceramic plates. Such distributions of the auxetic
component may also apply to the other embodiments described
herein.
[0047] Not all of the reinforcement layers necessarily include an
auxetic component, and embodiments may be provided which only have
an auxetic component in some of the layers. As will be appreciated
the multi-layered principles of this embodiment may be applied to
various structures having a combination of layers.
[0048] FIG. 6 shows a flow-chart of a method of manufacturing the
structure shown in FIG. 5. At step 600 two reinforced plates are
manufactured as described in one of the foregoing methods. At step
601 the plates are laid up with the composite structure using
conventional techniques. The structure is then cured at step 602
and a spall liner applied at step 603 if required. As will be
appreciated the structure could be co-cured to simplify the
manufacturing process.
[0049] FIG. 7 shows a cross-section of a reinforced ceramic plate
70 according to an embodiment of the current invention. In this
structure a ceramic plate 70 is formed with an integral auxetic
component 71. The auxetic component 71 may be provided using any of
the means described hereinbefore, for example an auxetic knit
structure, auxetic weave or auxetic fibres providing that they are
capable of resisting the firing temperature of the ceramic which is
typically 1250.degree. c.
[0050] The reinforcement of the structure shown in FIG. 7 provides
reinforcement and crack reduction due to the mechanisms described
above, and may therefore exhibit improved multi-hit resistance.
[0051] FIG. 8 shows a flow-chart of a method of manufacturing the
structure shown in FIG. 7.
[0052] At step 800 an auxetic reinforcement is placed on a first
surface of the ceramic plate mould. The auxetic reinforcement is
formed of a material that can resist the temperatures associated
with firing the ceramic plate. For example, carbon fibre woven into
an auxetic knit structure may be suitable.
[0053] At step 801 the mould is filled with the ceramic material,
typically as a powder or slurry but in some implementations the
mould filling may be by melt infusion or chemical vapour
infiltration particularly where the desired matrix required is
Silicon carbide. In this example a low cost high alumina ceramic
known as Grez ceramic may be utilised. At step 802 a further
reinforcement layer is applied to the other mould surface and the
mould is closed. The mould is then pressed at step 803 to form the
ceramic to shape and to integrate the reinforcement within, but
close to the surface of, the ceramic material. Alternatively the
reinforcement may be spread through the thickness of the ceramic
material, or may be applied only at one surface of the plate.
[0054] At step 804 the ceramic blank is removed from the mould and
fired according to conventional techniques. For example the blank
may be fired at 1250.degree. C. for 20 minutes.
[0055] The resulting structure is a ceramic plate with integral
auxetic reinforcement which may have the improved multi-hit
capability described previously.
[0056] The armour plates described hereinbefore may be formed in
any suitable dimensions as required by the application. The plates
maybe utilised in personal body armour, in vehicle armour or armour
for any other structure or device. The plates may be formed in any
shape or contour suitable for the required use and the parameters
of the structures are defined according to the protection required
for that use.
[0057] Reference has been made to ceramics in general and specific
examples of suitable ceramics may be Aluminium oxide (high alumina)
and silicon carbide.
[0058] Any suitable matrix may be utilised for the reinforcement
layers, for example thermoplastics, thermosetting plastics,
ceramics or metals.
[0059] Any suitable fibres may be utilised which will resist
processing in the reinforcement layer, for example glass fibre,
carbon fibre, aramid fibres and polyethylene fibres.
[0060] The reinforcement may be provided over the whole area of the
ceramic plate, or may be provided over only part of the plate.
Furthermore, the reinforcement may be provided in more than one
discrete region. Where reinforcement is provided on both surfaces
of the plate it may be provided in different regions on each
surface, or over the whole surface on both sides. The thickness,
amount or type of auxetic reinforcement may be varied over the area
of the ceramic plate, or on the different sides of the plate.
[0061] Multiple composite layers incorporating auxetic, and/or
conventional reinforcement may be provided on each of the
surfaces.
[0062] The reinforcement techniques described herein may also be
applied to the spall liner, which may be auxetically reinforced.
Also, such reinforcement may be provided in isolation of
reinforcement at the ceramic layers. Furthermore, the spall liner
could be provided using auxetic knitted or woven fabrics in the
absence of a matrix.
[0063] Any range or device value given herein may be extended or
altered without losing the effect sought, as will be apparent to
the skilled person.
[0064] It will be understood that the benefits and advantages
described above may relate to one embodiment or may relate to
several embodiments. It will further be understood that reference
to `an` item refers to one or more of those items.
[0065] The steps of the methods described herein may be carried out
in any suitable order, or simultaneously where appropriate.
Additionally, individual blocks may be deleted from any of the
methods without departing from the spirit and scope of the subject
matter described herein. Aspects of any of the examples described
above may be combined with aspects of any of the other examples
described to form further examples without losing the effect
sought.
[0066] It will be understood that the above description of
preferred embodiments is given by way of example only and that
various modifications may be made by those skilled in the art. The
above specification, examples and data provide a complete
description of the structure and use of exemplary embodiments of
the invention. Although various embodiments of the invention have
been described above with a certain degree of particularity, or
with reference to one or more individual embodiments, those skilled
in the art could make numerous alterations to the disclosed
embodiments without departing from the spirit or scope of this
invention.
* * * * *