GB2492585A - An Armour System - Google Patents

Abstract

An armour system comprises an array of closely tessellating ceramic tiles (11) encased within a casing (12) configured to restrict movement of the ceramic tiles. The casing (12) comprises a polymer composite attached in a pressure-controlled environment to a surface of the array of ceramic tiles (11) to hold the ceramic tiles (11) together..

Description

An Armour System The present invention relates to an armour system comprising an array of ceramic tiles. More specifically, the present invention relates to a ceramic-based armour system that offers improved protection against multiple ballistic hits. The invention also provides for fabricating an armour system having one or more ceramic-based tile.

Such armour systems typically comprise a metallic or ceramic plate arranged to cover an area to be protected, such as in a padded vest, to protect a person wearing said vest from being injured by projectiles. Large plates of these materials may also be used to provide protection to a vehicle or structure.

Ceramic-based armour systems have an advantage over metal-based armour systems due to the ability of certain ceramic materials to provide a low-weight yet strong barrier against projectiles.

Advanced ceramics, such as silicon carbide, are extremely hard, which is an essential physical attribute for an armour plate in order to prevent a projectile from penetrating its surface. As an example, silicon carbide is over four times harder than stainless steel. However, although they can be extremely hard, advanced ceramics typically lack toughness, which makes them prone to fracture upon impact of a projectile. Using silicon carbide and stainless steel again as comparative examples, stainless steel is around 40 times tougher than the advanced ceramic.

US-B-7849779 discloses an improved polymer matrix reinforced ballistic armour ceramic tile further comprising a backing and a polymer composite which is applied to the ceramic tile by direct heat and pressure bonding.

A problem with existing ceramic-based armour systems such as the one described above, for example, is that upon impact by a first projectile, the ceramic plate will typically fracture which, while preventing penetration of its surface, weakens the plate and makes the armour system vulnerable to further projectile impacts.

It is therefore a principal aim of the present invention to provide a ceramic based armour system with improved multiple impact performance. It is a further or alternative aim to provide an improved method of fabricating an armour system.

According to the present invention, there is provided an armour system, comprising an array of two or more closely tessellating ceramic tiles encased within a casing configured to restrict movement of the ceramic tiles, the casing comprising a polymer composite attached to a surface of the array of ceramic tiles in a pressure-controlled environment to hold the ceramic tiles together.

It will be appreciated that by using a plurality of closely tessellating ceramic tiles to cover the same area as a large single ceramic tile, should a projective impact upon one of the tiles, only a small area of the armour system will be compromised, and the remaining intact tiles will continue to offer protection.

Preferably, the polymer composite includes glass fibres, aramid fibres or carbon fibres since each of these types of fibres provides a strong and lightweight material when used in a polymer composite. The polymer composite may comprise multiple layers of fibres. Preferably first and second layers of fibres are arranged such that fibres in a first layer are perpendicular to fibres in a second layer, as this provides strength to the polymer composite.

Preferably, the fibres in the polymer composite are woven together, which is a stronger arrangement of the fibres.

The polymer composite may be cured directly onto at least one face of the array of ceramic tiles to ensure good adhesion of the composite to the tiles.

The casing may wrap part way or all the way around the array of tiles so that it can adhere to multiple surfaces of the array.

Preferably, the casing may also comprise a resin pre-impregnated with a plurality of fibres, which improves the strength of the resin casing while adding little additional weight. Such a resin system can be part of an inner layer adhered directly to the array or may be part of one or more additional layer that can be formed therearound.

A backing section may be provided to help ensure the correct close alignment and tessellation of the array of ceramic tiles or provide additional strength. This backing section can be in direct contact with the tiles or may be attached to the tile array once that array is held together by the polymer composite. Preferably, the backing section is incorporated as part of the casing, for example forming all or part of one side of a casing that goes all the way around the ceramic tiles. The backing section may be formed wholly or in part from at least one of a metal, ultra-high-molecular-weight polyethylene (UHMWPE), aramid fibres, glass fibres arid PBO (polybenzoxazole) fibres, each of which are a strong, preferably lightweight, material to improve the strength of the body armour.

Preferably, the ceramic tiles are each substantially identical in shape, and are of a shape which allows a closely tessellating array to be formed with as few gaps as possible between neighbouring tiles. Hexagonal or square tiles tessellate closely and are preferred. A mixture of different tile shapes can be used as long as they can form a pattern that tessellates or leaves only very small gaps, ideally sub 1mm.

The tiles can be made of any engineering ceramic material deemed to have the necessary properties for ballistic performance, such as Boron Carbide, Silicon Carbide, Aluminium Oxide and Silicon Nitride. This is, however not an exhaustive list and any suitable ceramic having the necessary properties for ballistic performance, such as hardness, may be suitable.

Tiles in an armour system according to the present invention, suitable for a body vest, for example, are typically 30-100mm in diameter, and make up a plate of approximately 300mm x 250mm.

According to a second but closely related aspect of the present invention there is also provided a method of fabricating an armour system, comprising the steps of: arranging one or more ceramic tiles into a shape; covering the surface of the tile arrangement with a polymer composite; curing the polymer composite onto the surface of the tile arrangement in a pressure-controlled environment; and encasing the tile arrangement within a casing configured to restrict movement of the tile arrangement.

In this method advantages can be obtained even when only one tile is covered, however often the method will be used for an array of 2 or more tiles.

It will be appreciated that fabricating an armour system in a pressure-controlled environment improves tile confinement such that a thinner lighter tile may be used to give the same performance, despite the fact that the surface area of each tile in the array is significantly smaller than that of a single tile substantially the same size as the array.

Preferably, the polymer composite is adhered to the ceramic under a pressure of between about O.1MPa to about 1.OMPa, which is the typical working pressure range of an autoclave, and above vacuum pressure.

A backing component is, preferably, arranged onto a polymer composite covered surface of the tile arrangement before the polymer composite is cured.

Composite encapsulation of the tile arrangement by the polymer composite under a controlled pressure has been found to improve adhesion characteristics of the armour system and hence attachment to a backing, or other encasing, component since the polymer composite material has much better adhesion characteristics than ceramics such as, say, Silicon Carbide.

The curing time and temperature are determined by the cure cycle of the resin system used within the composite, so can vary greatly.

By way of example only, a specific embodiment of the present invention and a method will now be described in detail, with reference being made to the accompanying drawings, in which:-Figure 1 shows a cross-section of an armour system according to the present invention; Figure 2 shows a plate comprising the armour system of the present invention having a section cut-away; Figure 3 shows an exemplary array of closely tessellating hexagonal tiles forming the shape of the plate in Figure 2; Figure 4 shows a body vest including the armour system of the present invention; Figures 5(a)-(d) are various examples of closely tessellating tiles shapes, which may be used with the present invention; and, Figure 6 shows two interwoven layers of a polymer composite.

Referring initially to Figure 1, an armour plate 10 comprises a plurality of closely tessellating ceramic tiles ha, lib arranged to form the shape of the armour plate 10 within a casing 12 of a corresponding shape. In this example, the casing 12 is resin-based. The tiles ha, lib are encased within a polymer compound 13 and attached to a backing 14 before being secured within the casing 12.

Figure 2 shows a typical shape of an armour plate 10. Also shown is an armour plate 10 having a section (generally indicated by "A-A") cut-away to expose the array of tiles 11, encased within the polymer compound 13 and attached to a backing 14, contained within.

Figure 3 shows a schematic of how the plurality of ceramic tiles 11 may be arranged in an array to form the shape of an armour plate. In this example, hexagonally shaped tiles are used, although those around the edge may be of differing shapes.

In figure 4, a body vest 15 comprising an armour system according to the present invention is generally shown. The body vest 15 comprises an outer body 16, in this example comprising a textile material, which may be water resistant, or have other desirable properties, an inner body 17 which in use locates the body vest 14 against the body of a person wearing it, and an armour plate 10. Ideally, a pocket (not shown) is provided on the inner side of the outer body 16 for retaining the armour plate 10.

Although preferably identical, the tiles 11 may be any number of different shapes that can closely tessellate, such as regular hexagons, rectangles, triangles, as illustrated in Figures 5(a)-(c), or a combination of different shapes, such as hexagons and triangles as illustrated in Figure 5(d), provided that they closely tessellate with little or no gaps between neighbouring facets. Hexagons are preferred.

To encase an arrangement of one or more ceramic tiles 11, the polymer composite 13, which may include glass fibres, aramid fibres or carbon fibres, and can be wet lay-up, resin transfer or pre-impregnated, for example, is preferably arranged in two perpendicular layers over the tile(s). The two layers of fibres are, ideally, combined in one interwoven layer as shown in Figure 6.

The polymer composite 13 is, preferably, attached to the surface of the array of tiles 12 under a conditions where the pressure is controlled to be between about 0.2MPa and about 1.OMPa, the tiles typically being processed in an autoclave, or similar. The tiles may also be heated during that process, depending on the cure cycle of the resin system employed in the composite, for example 120°C for 90 minutes in the case of standard epoxy based resins.

Ideally, the polymer composite 13 is cured directly onto the surface of the tiles 11 A backing may be attached to the polymer composite, and hence the tile(s), during the same curing process. Further encasing layers may be arranged around the tiles 11 and/or backing 14.

Composite encapsulation improves adhesion characteristics for the array of tiles for attachment to other encasing or backing components (not shown).

These may be incorporated into a resin system that forms a further part of the casing prior to the plate being mounted in the vest 10. The backing plate and further encasing or backing components may comprise at least one of a metal, ultra-high-molecular-weight polyethylene (LJHMWFE), aramid fibres, glass fibres and FBO fibres, or resin. The resin may be pre-impregnated with carbon fibre, glass fibre, aramid fibres, or similar.

Claims (1)

1. <claim-text>CLAIMS1. An armour system, comprising an array of two or more closely tessellating ceramic tiles encased within a casing configured to restrict movement of the ceramic tiles, the casing comprising a polymer composite attached to a surface of the array of ceramic tiles in a pressure-controlled environment to hold the ceramic tiles together.</claim-text> <claim-text>2. The armour system of claim 1, wherein the polymer composite comprises glass fibres, aramid fibres or carbon fibres.</claim-text> <claim-text>3. The armour system of claim 1 or 2, wherein the polymer composite comprises a first and second layer arranged such that fibres in a first layer are perpendicular to fibres in a second layer.</claim-text> <claim-text>4. The armour system of claim 3, wherein the fibres in the polymer IS composite are woven together.</claim-text> <claim-text>5. The armour system of any preceding claim, wherein the polymer composite is cured directly onto the array of ceramic tiles.</claim-text> <claim-text>6. The armour system of any preceding claim, wherein the casing also comprises a resin that may be pre-impregnated with a plurality of fibres.</claim-text> <claim-text>7. The armour system of any preceding claim, further comprising a backing section.</claim-text> <claim-text>8. The armour system of claim 7, wherein the backing section is incorporated into the casing.</claim-text> <claim-text>9. The armour system of claim 7 or 8, wherein the backing section comprises at least one of a metal, ultra-high-molecular-weight polyethylene (UHMWPE), aramid fibres, glass fibres and PBO fibres.</claim-text> <claim-text>10. The armour system of any preceding claim, wherein the ceramic tiles are all substantially identical in shape.</claim-text> <claim-text>11. An Armour system as claimed in claim and substantially a herein described and illustrated in the accompanying drawings.</claim-text> <claim-text>12. A method of fabricating an armour system, comprising the steps of: arranging one or more ceramic tiles into a shape; covering the surface of the tile arrangement with a polymer composite; curing the polymer composite onto the surface of the tile arrangement in a pressure-controlled environment; and encasing the tile arrangement within a casing configured to restrict movement of the tile arrangement.</claim-text> <claim-text>13. The method of claim 12, wherein the step of adhering the polymer composite is performed under a pressure of between about 0.1 MPa to about 1.OMPa.</claim-text> <claim-text>14. The method of claim 12 or 13, further comprising the step of arranging a backing component onto a polymer composite covered surface of the tile arrangement before curing the polymer composite.</claim-text>