CLAIM OF PRIORITY

This application claims the priority benefit from Indian Provisional Patent Application number 780/CHE/2011 filed by Tata Advanced Materials Ltd at Indian Patent Office, Chennai on 14th March 2011
and entitled "Light weight composite ballistic armor panel and the method thereof.

The following specification particularly describes the invention and the manner in which it is to be performed:

1. Technical field of the invention
The invention relates to lightweight composite ballistic armor panel for use in vehicle and personnel body armor applications.

2. Background of the invention

Armor is a protective shield used to prevent damage from being inflicted by an object, individual or a vehicle through a direct contact weapons or high velocity projectiles, usually during combat, or from the damage caused by a potentially dangerous environment or action. Various kinds of armors are available that vary in shape and size to fit the object to be protected.

The steel armor plate being widely used has been quite satisfactory from the protection against projectiles such as .30 and .50 caliber shell but the weight of steel plate adds greatly to the weight of the vehicle thereby reducing markedly its mobility and usefulness. So far a number of other materials such as synthetic fibers, plastics, adhesives and ceramics have been used in constructing such armors. Among these, ceramics in constructing armors has gained popularity because of some of its useful properties such as light weight, rigidity, resistance to heat, abrasion and compression etc.

In conventional armour systems, monolithic ceramic plates are used in the armor design, which have low tensile, low flexible strength and poor fracture toughness. Due to this, the plates generally tend to crack or shatter in response to the shock received from an incoming projectiles/impact. Such type of damage weakens the armor panel and so allows penetration of later projectiles, striking within an area of a few centimeters around the first point. Further this reduces multi-hit capability. In order to overcome the shortcomings of the monolithic ceramic plate, the ceramic has been used in the form of tiles or pellets. Depending on the threat level, the size of the pellets has to be varied, which increases overall the weight of the armor. Also during projectiles hit, ceramic fragments or splinters tend to come out of the armor panel which are more dangerous than projectile for body armor products.

Hence, there is need for lightweight armor systems that provides close multi-hit capabilities with less damage and less back face deformation (in case of body armor). Furthermore, there is need for reducing the overall weight and cost of the armor systems along with design flexibility.

3. Summary of the invention

The present invention minimizes the above mentioned shortcomings in the prior art and provides a lightweight composite ballistic armor panel having composite layer made of at least one ceramic layer of closely packed ceramic pellets/tiles arranged in between at least two mutually parallel layers of fabric network structure having means, to receive and to hold, plurality of ceramic pellets/tiles wherein the fabric network structure conforms the alignment of the ceramic pellets/tiles to the same geometric plane by holding them together and parallel to each other. The space formed within the ceramic pellets/tiles is filled with adhesive matrix that diffuses the shock resulting from the impact and also prevents said ceramic pellets/tiles near the impact area from fracturing by constraining the fractured ceramic pellet/tile to a limited area whereby preserving the ballistic capability of neighboring ceramic pellets/tiles from future projectile impacts and improving the multi-hit capability of the composite ballistic armour and less back face deformation (in case of body armor). The ceramic pellets/tiles used in the ceramic layer are provided with slots around the circumference on the upper end and lower end for being engaged tightly inside the openings provided on the fabric network structure wherein the openings on the fabric network structure are configured to always keep the ceramic pellets/tiles in vertical position by enclosing them tightly in between two parallel layers of fabric network structure whereby preventing ceramic pellets/tiles from undesirable displacement while in movement or operation. The shape of ceramic pellets is cylindrical, whereas the shape of the ceramic tiles may be of hexagonal, rectangular, pentagonal, triangular, spherical, octagonal and square. Pellets/tiles have at least one convexly contoured upper end or lower end. In one embodiment, the fabric network structure comprises a uniform mesh having horizontal and vertical pattern of openings configured to receive and engage the slots provided on the ceramic pellets/tiles. In another embodiment, the network structure is in the form of honeycomb core with uniform openings wherein the said honeycomb core is selected to suit the dimensions of pellets/tiles and openings are suitable to receive and engage said ceramic pellets/tiles. The said network structures is made of a material selected from the group consisting of polymers, elastomers and paper to keep the
ceramic pellets/tiles in a uniform arrangement whereby reinforcing the ceramic layer during high velocity ballistic impact and improving the flexural stiffness of the ceramic layer. To the upper surface of the composite layer, a front entrapment system is bonded to entrap fragments of the damaged ceramic pellets/tiles when hit by a projectile. The front entrapment system comprises at least one fiber reinforced composites layer bonded to the upper surface of the composite layer using thermoset plastic or thermoplastic to keep the ceramic fragments intact within the armour panel after a projectile impact. At least one fabric layer is bonded to the upper surface of the fiber reinforced composite layer using adhesive wherein the fabric layer is made of a material selected from aramid fabric, carbon fabric or equivalent ballistic grade material for front entrapment. The front entrapment system also includes at least one foam layer bonded to the upper surface of the fabric layer using elastomeric adhesive wherein the foam layer is preferably made of cross linked polyethylene foam material. In another embodiment, the fibre reinforced composite layer is made of hybrid form of glass fiber reinforced composite and aramid fibre. To the back surface of the composite layer, a back spall system is bonded that comprises at least one shock absorbing backup wad layer bonded to the back surface of the composite layer using adhesive for diffusing the shock resulting from the projectiles impact. The back spall system also includes at least one spall layer bonded to the back surface of the shock absorbing wad layer using elastomeric adhesive wherein the spall layers are made of materials selected from group of aramid fabric, carbon fabric or equivalent ballistic grade materials. The shock absorbing backup wad layer made of a material selected from group consisting of high performance fibres, fabrics, metals, alloys or composites. The shock absorbing backup wad layer diffuses the shock resulting from the high velocity projectile impact. All the layers in the armor penal are wrapped in polyurethane coated nylon fabric layer using the elastomeric adhesive.

The composite ballistic armor panel provides multi hit capability since the propagation of crack is arrested as the crack travels from the point of incidence to the boundaries of the pellets/tiles. Also the crack can't propagate further due to interspatial adhesive matrix between the pellets/tiles and material discontinuities between the layers of the panel. The armor panel blunts, deflects and/or breaks up the projectiles that come in its contact thereby reducing the penetration of projectiles through the composite ballistic armor panel. The usage of ceramic pellets/tiles overcomes the shortcomings of monolithic ceramic plates that can crack down and shatter in response to the shock of an incoming projectiles/impact due to their basic material properties. The manufacturing cost of the armor system is substantially low as compared to convention armour systems since the raw materials such as adhesives, plastics, fibers and ceramic materials used in the composite armour system are quite inexpensive and are easily available. The armor panel can be locally repaired where the projectiles have impacted rather than replacement of the whole armor panel on impact of projectiles as is done traditionally. The usage of ceramic pellets/tiles in the invention provides a light weight armor panel for the same level of protection as is provided with conventional heavy armor systems.

4. Brief description of the drawings:

FIG 1 illustrates the cross sectional view of the composite ballistic armor panel in accordance with one embodiment of the invention.

FIG 2a illustrates the orthogonal top view of the ceramic pellet in accordance with one embodiment of the invention.

FIG 2b illustrates the prospective view of the ceramic pellet in accordance with one embodiment of the invention.

FIG 2c illustrates the orthogonal front view of the ceramic pellet in accordance with one embodiment of the invention.

FIG 2d illustrates the orthogonal front view of the ceramic pellet with flat base in accordance with one embodiment of the invention.

FIG 3a illustrates the orthogonal front view of the hexagonal ceramic tile in accordance with one embodiment of the invention.

FIG 3b illustrates the orthogonal top view of the hexagonal ceramic tile in accordance with one embodiment of the invention.

FIG 3c illustrates the orthogonal bottom view of the hexagonal ceramic tile in accordance with one embodiment of the invention.

FIG 3d illustrates the prospective view of the hexagonal ceramic tile in accordance with one embodiment of the invention.

FIG 4a illustrates the prospective view of the fabric network structure with horizontal and vertical pattern, in accordance with one embodiment of the invention.

FIG 4b illustrates the prospective view of the honeycomb fabric network structure, in accordance with one embodiment of the invention.

FIG 5a illustrates the prospective view of the arrangement of ceramic pellets on fabric network structure in accordance with one embodiment of the invention.

FIG 5b illustrates the prospective view of the composite ballistic armor panel in accordance with one
embodiment of the invention.

FIG 6 illustrates the method of manufacturing composite ballistic armor panel in accordance with one embodiment of the invention.

5. Detailed description of the invention:

Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.

The composite ballistic armor panel absorbs and dissipates kinetic energy from high velocity projectiles received on its surface and prevents the projectile from penetrating the object shielded by the armor panel. When a projectile strikes a body armor panel, it absorbs and disperses the energy of the impact across a generalized area.

The lightweight composite ballistic armor panel comprises composite layer made of a ceramic layer of closely packed ceramic pellets/tiles arranged in between two mutually parallel layers of fabric network structure having means, to receive and hold, plurality of ceramic pellets/tiles having slots around the circumference on the upper end and lower end for being engaged tightly inside the openings on the fabric network structure to always keep the ceramic pellets/tiles in same geometric plane by enclosing them tightly in between two parallel layers of fabric network structure. The adhesive matrix is filled in ceramic layer to receive and to hold the pellets/tiles in a place and on impact it prevents the ceramic body from fracturing by constraining the fractured ceramic pellet/tile to a limited area whereby preserving the ballistic capability of neighboring ceramic pellets/tiles from future projectile impacts and improving the multi-hit capability of the composite ballistic armour with less backface deformation.

FIG 1 illustrates the cross sectional view of the composite ballistic armor panel in accordance with one embodiment of the invention. In most preferred embodiment, the composite ballistic armor panel comprises three major sections namely: composite layer 120, front entrapment system 130 and back spall system 110.

Composite Layer

The composite layer 120 of the composite ballistic armour panel comprises at least one ceramic layer 104 having a plurality of ceramic pellets 201 (FIG 2) or ceramic tiles 301 (FIG 3) of various sizes and shapes. In one embodiment, the ceramic tile 301 is having a flat or at least one convexly contoured upper end or lower end. The shape of the ceramic tiles 301 may be rectangular, pentagonal, hexagonal, triangular, spherical, octagonal or square. In another embodiment, ceramic pellets 201 may be used that are substantially cylindrical in shape and have a flat or convexly curved top end and a flat/convexly curved lower end. The ceramic pellets 201 or ceramic tiles 301 may comprise at least one material selected from alumina, glass, boron carbide, boron nitride, silicon oxide, silicon nitride, silicon carbide, magnesium oxide, silicon aluminum oxynitride and mixtures thereof. The size of each ceramic pellet 201 or ceramic tiles 301 and their binding determines the ballistic protection level provided by the armor. The ceramic pellets 201 or ceramic tiles 301 serve to blunt and deflect and/or break up the projectiles that come in their contact thereby reducing the penetration of projectiles through the composite ballistic armor panel.

In one embodiment, the ceramic pellets/tiles in the ceramic layer 104 are packed closely and are bound and retained in flat horizontal plate position by fixing them uniformly on one side of pressure sensitive adhesive tape in a mold. The pressure sensitive tape is a two sided adhesive tape having adhesive material applied on both the sides. Alternatively, instead of using an adhesive tape, an adhesive matrix may be poured inside the space formed within the ceramic pellets 201 or ceramic tiles 301. The adhesive matrix may be any suitable materials such a thermoplastic or a thermoset plastic. In another embodiment, the ceramic pellets 201 may be bonded to the one side of pressure adhesive tape and tied with the fabric network structure (s) 103. Alternatively, instead of using an adhesive tape, an adhesive matrix may be poured on a layer of arranged ceramic pellets 201 which are tied with the fabric network structure (s) 103 having means, to receive and to hold, a plurality of closely packed ceramic pellets for conforming the alignment of the ceramic pellets to the same geometric plane. The adhesive matrix may comprise at least one material selected from a thermoplastic or a thermoset plastic. The fabric network structure 103 resembles a web which may be made of polymer/elastomer/paper to keep the pellets/tiles in a desired arrangement and reinforces the ceramic layer 104 layer during ballistic impact. In addition, it gives resistance to tensile load that is generated during impact and improves the flexural stiffness of the ceramic layer 104. The horizontal plate with plurality of ceramic pellets 201 or ceramic tiles 301 are bonded to shock absorbing backup wad 102 on other side of the adhesive tape or by means of adhesive. The adhesive matrix material used in preparing the ceramic layer 104 absorbs energy by diffusing the shock resulting from the impact, which not only prevents the ceramic pellets 201 or ceramic tiles 301 near the impact area from fracturing but also constrains the fractured ceramic pellets/tiles. Thus, the matrix material preserves the ballistic capability of neighboring ceramic pellets 201 or ceramic tiles 301 for future impacts and improves the multi-hit capability of the composite ballistic armour since the propagation of crack is arrested as it travels from the point of incidence to the boundaries of the pellets/tiles and cannot propagate further due to discontinuities in the medium and interspatial adhesive matrix between the pellets/tiles. In another embodiment, the pellets/tiles are embedded in the openings of hexagonal core network structure wherein the honeycomb core is selected to suit and the dimensions of pellets/tiles. The adhesive matrix may comprise at least one material selected from a thermoplastic or a thermoset plastic.

Front entrapment system

In the armor panel, front side or strike face is called as front entrapment system 130 which further comprises at least one fiber reinforced composites layer 105, aramid fabric layer 106, at least one foam layer 107. On top of all the above layers, a layer of polyurethane coated nylon fabric is disposed. During projectiles hit, ceramic fragments/splinters tend to come out which are more dangerous than projectile for body armor products. Hence to keep the ceramic fragments/splinters intact within the system, at least one layer of fiber reinforced resin composite 105 is directly bonded/laminated to the upper surface of the ceramic layer 104 using thermoplastic or thermoset resin such as epikote or epoxy, during manufacturing. The fiber that may be used for an application may be made of glass. For higher level threats [NIJ level IV] carbon/aramid and combination thereof may be used. There is at least one fabric layer 106 bonded on upper surface of fiber reinforced composite layer 105 using adhesive wherein said fabric layer is made from a material selected from group of aramid fabric, carbon fabric or equivalent ballistic grade materials for front entrapment. At least one more foam layer 107 is bonded to the upper surface of the fabric layer 106 layer using elastomeric adhesive wherein the foam layer is preferably made of cross linked polyethylene foam material. The elastomeric adhesive used may be neoprene or polyurethane based. The thickness of said foam layer depends upon the level of threat. The front entrapment system 130 serves to entrap fragments of the damaged ceramic pellets when hit by a high speed projectile.

Back spall system
The lightweight composite ballistic armour panel also includes a back spall system 110 bonded to back surface of the composite layer 120. The back spall system 110 comprises at least one shock absorbing backup wad layer 102 bonded to the back surface of the composite layer 120 using adhesive for diffusing the shock resulting from the projectiles impact. The shock absorbing backup wad layer 102 may be made of material selected from group of high performance fibres, high performance fabrics, metals, alloys or composites. The backup wad layer 102 diffuses the shock resulting from the projectiles impact. Alternatively, aramid fabric layer (s) may be bonded to the back surface of the backup wad layer 102 with the elastomeric resin in order to improve the bonding efficiency of the two layers. After this, at least one spall layer 101 is bonded to the back surface of the backup wad layer 102 using elastomeric adhesive wherein said spall layer are made of layers of aramid fabric. Alternatively, the spall layer 101 may be made of carbon or equivalent ballistic grade material for higher level of threat. Finally, all the layers of composite ballistic armor panel are wrapped with polyurethane coated nylon fabric layer 108/109 using the elastomeric adhesive.

The table below illustrates some of the materials used in the manufacture of composite ballistic armor in one of embodiment of the invention.

FIGS 2a, FIG 2b, FIG 2c illustrate the orthogonal top, prospective and orthogonal front view respectively of the ceramic pellet, in accordance with various embodiments of the invention. The ceramic pellet 201 is preferably cylindrical in shape and having at least once convexly contoured upper end 202 or lower end 203. Each ceramic pellet 201 is provided with an upper slot 204 just below the upper end 202 and another lower slot 205 just above the lower end 203 for being engaged tightly inside the openings provided on the fabric network structure 103 wherein the openings on said fabric network structure are configured to always keep said ceramic pellets in vertical position by enclosing them tightly in between two parallel layers of fabric network structure for preventing ceramic pellets from undesirable displacement while in movement or operation.

FIG 2d shows the orthogonal front view of the ceramic pellet with flat lower end in accordance with one embodiment of the invention. In this embodiment, only the lower end 203 of the ceramic pellet 201 is flat.
FIGS 3a, FIG 3b, FIG 3c and FIG 3d illustrate the orthogonal front view, orthogonal top view, orthogonal bottom view and prospective view respectively of the hexagonal ceramic tile in accordance with one embodiment of the invention. In one of the embodiments, the ceramic tile 301 is hexagonal in shape with convexly contoured upper end 302 and a flat lower end 303. The ceramic tile 301 may also be provided with an upper slot 304 just below the upper end 302 and another lower slot 305 just above the lower end 303 on the ceramic tiles 301. The upper slot 304 and the lower slot 305 are configured to always keep the ceramic tile 301 in parallel position by enclosing them tightly in between at least two parallel layers of fabric network structure 401 (FIG 4b) with hexagonal pattern and prevent them from undesirable displacement while in movement or operation.

FIG 4a illustrates the prospective view of the fabric network structure with horizontal and vertical pattern, in accordance with one embodiment of the invention. The fabric network structure 103 comprises a uniform mesh having horizontal and vertical pattern of openings 112 configured to receive and engage the upper slot 204 and the lower slot 205 provided on each ceramic pellet 201.

FIG 4b illustrates the top view of the honeycomb fabric network structure, in accordance with one embodiment of the invention. The fabric network structure 401 comprises a uniform mesh having openings in honeycomb pattern wherein the openings 402 are configured to receive and engage the upper slot 304 and lower slot 305 provided on each ceramic pellet 301.

FIG 5a illustrates the prospective view of the arrangement of ceramic pellets on fabric network structure in accordance with one embodiment of the invention. The layer of ceramic pellets 201 is entrapped in between two parallel layers 103a and 103b of the fabric network structure 103. In another embodiment, a layer of uniformly arranged ceramic tiles 301 can be entrapped in between two parallel layers 103a and 103b of fabric network structure 401.

FIG 5b illustrates the prospective view of the composite ballistic armor panel in accordance with one embodiment of the invention. First of all, one layer of ceramic pellets 201 or ceramic tile 301 is arranged on the lower layer 103a of the fabric network structure 103 by fixing their lower slot 205 tightly inside the space 112 provided on the first layer 103a. After arranging ceramic pellets 201 on the lower layer 103a of fabric network structure 103, another upper layer 103b of fabric network structure 103 is laid and the slot 204 of each ceramic pellet 201 is fixed inside the space 112 on the upper layer 103b of the fabric network structure 103. The same procedure is repeated for ceramic tiles 301.

FIG 6 illustrates the method of manufacturing composite ballistic armor panel in accordance with one embodiment of the invention. The process initiates at step 601 by first arranging and binding a layer of ceramic pellets 201 or ceramic tiles 301 on the flat surface of a mold of suitable dimensions. The ceramic pellets 201 are further arranged uniformly and tied to the layer(s) of fabric network structurel03 (In case of ceramic tiles 301, the tiles are arranged on the Iayer(s) of hexagonal fabric network structure 401). The fabric network structure 103 keeps the ceramic pellets/tiles in a desired arrangement and reinforces the ceramic layer 104 during ballistic impact. In one embodiment, one side of the pressure sensitive adhesive tape is bonded to the arranged ceramic pellets 201 or ceramic tiles 301. In alternative embodiment, an adhesive matrix can also be poured on the fabric network structure 103 to bind the ceramic pellets 201 or ceramic tiles 301 together instead of using adhesive tape. The adhesive matrix may be a thermoplastic or a thermoset. Depending upon the adhesive used, an appropriate curing procedure is followed. The fabric network structure 103 gives resistance to tensile load that is generated during impact and improves the flexural stiffness of the ceramic layer 104.

In the next step 602, the ceramic layer 104 is lifted slowly from the mold and bonded to another shock absorbing backup wad layer 102 which is made of material selected from high performance fibers, fabric, metals, alloys or composites. Alternatively, aramid layer (s) is bonded directly to the back surface of the ceramic layer 104. A pre cut backup wad layer 102 is physically matched to the dimension of the ceramic layer 104 and bonded together. In one embodiment, in case, pressure sensitive tape is used in step 601, the backup wad layer 102 is bonded to the back surface of the adhesive tape and appropriate load is applied on it for sufficient time in order to ensure proper adhesion between the backup wad layer 102 and ceramic layer 104. The backup wad layer 102 diffuses the shock resulting from the projectiles impact.

In another embodiment, where ceramic pellets 201 or ceramic tiles 301 are bonded with the resin at step 601, the backup wad layer 102 is bonded to the back surface of the ceramic layer 104 by applying a sufficient quantity of elastomeric adhesive on it. Adhesive is first applied on the backup wad layer 102 and then on the back surface of the ceramic layer 104 to bond them properly. In order to remove the entrapped air and to improve the bonding efficiency the upper surface of the backup wad layer 102 is properly squeezed with sufficient pressure by using suitable fixtures or manually applying weight on its upper surface during bonding. After squeezing, excess adhesive is wiped out from the edges, if any. This operation has to be performed within working time of adhesive system. The whole layer assembly must be kept undisturbed until the layers have been bonded thoroughly or completely cured. After which the weight or clamps placed on them are removed. The layers assembly is sent for the next operation.
In next step 603, single or multiple layers of fiber reinforced composite 105 is bonded on upper surface of the ceramic layer 104. For this, the plate with arranged ceramic layer 104 is preheated in the oven. Then, the preheated ceramic layer 104 is placed on a tripod stand and a coat of resin mix is brushed evenly on it. A pre cut layer of a glass fabric is placed and allowed to wet out with the applied resin layer. The glass fabric is preferably a woven roving mat. In alternate embodiment, the fabric may be made of carbon or aramid (for higher threat beyond NIJ level IV). The orientation of the fiber reinforced composite layer 105 is kept as squarely as possible. Extra resin is wiped off from the outer edges of the layers. The layer assembly may be kept in a hot oven incase post curing is required or else room temperature curing may be performed. The layer assembly is removed from the oven after curing and allowed to cool down completely. After curing the layer, it is trimmed off neatly using a sharp object such as a knife. The edges are sand off to remove burrs form the layer assembly. This layer keeps the ceramic fragments/splinters intact within the system and also, improves the stiffness of the ceramic layer 104.

In the next step 604, optionally, a front entrapment layer 106 may be bonded on upper surface of the fiber reinforced composite layer 105 for capturing fragment/splinter during impact. The front entrapment layer 106 comprises a single or multiple aramid fabric layers which is cut using certified template using Brute™ cutting machine on marked lines. The aramid fabric layer 106 is then bonded to upper surface of the fiber reinforced composite layer 105 using polyurethane or neoprene based elastomeric adhesive. The front entrapment layer 106 serves to entrap the flying debris e.g. fragments of the projectiles and/or the ceramic material.

In the next step 605, a polyethylene foam layer 107 is bonded on upper surface of the aramid fabric layer 106 for front entrapment or support. A layer of foam material is marked using certified templates and then cut using Bruite™ cutting machine/knife on marked lines. The foam layer 107 is bonded on upper surface of the aramid fabric layer 106 using the elastomeric adhesive.

In next step 606, the spall layer 101 comprising, aramid fabric is bonded to the back surface of the backup wad layer 102 using elastomeric adhesive. Load is applied manually on the whole layer assembly with the help of a squeezer/fixture and then allowed it to dry.

In next and final step 607, another layer of nylon fabric 108 & 109 is bonded on the upper surface of the foam layer 107 and on the back surface of the bottom most spall layer 101. The nylon fabric is preferably coated with polyurethane (PU). The nylon fabric is spread on cutting table and the cutting layout is marked using certified template. The nylon fabric is cut using Bruite/Lectra cutting machine on the marked lines. After this, adhesive is applied on the layer assembly i.e. on upper surface of the foam layer 107 and at the back surface of the spall layer 101.

EXPERIMENTS AND RESULTS:

Armor panels of dimension 30 cm X 30 cm were prepared according to process flow mentioned under FIG 6 and tested as per NIJ standard 0101.04. The ceramic pellets (both Alumina & Silicon-Boron Carbide) with specific gravity in the range of 2.5 to 3.8 have been used. The cylindrical ceramic pellets are having convexly contoured upper end and lower end as shown in FIG 2C. The diameter of the ceramic pellets was in the range of 8.0 tol2.0 mm and total height of the ceramic pellets was in the range of 8.0 to 10 mm. The ceramic pellets were bound in adjacent rows using network structure made of polymer. The adhesive matrix used to fix said ceramic pellets was polyurethane resin. Back spall system constituted the HPPE wad and aramid liners. Front entrapment system was made of hybrid form of glass fiber reinforced composite with aramid. This combination was encapsulated with cross linked polyethylene foam and polyurethane coated water resistance nylon fabric. The areal density (a function of the size and composition of pellets) of the armor panels was in the range of 35 to 42 Kg/M .

The armor panels were tested by 0.3 caliber M2 AP bullets fired at velocity of 878 ± 9.1 m/sec at 0° incidence and at a distance of 15 meters from the target. The bullet couldn't penetrate through the armor panel, and ballistic trials were successful.

Industrial Applications:

The armor panel can be used both for vehicle armor and personnel body armor applications. The usage of ceramic pellets/tiles in the invention provides a light weight option as compared to conventional heavy armor systems for the same level of protection.
The composite ballistic armor panel provides multi hit capability. The manufacturing cost of the armor system is substantially low as compared to convention armor systems since the raw materials such as adhesives, plastics, fibers and ceramic materials used in the composite armor system are quite inexpensive and are easily available. The armor panel can be locally repaired where the projectiles have impacted rather than replacement of the whole monolithic armor panel which gets destroyed in the process.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments and that the present invention may be embodied in other specific form without departing from the spirit or essential attributes thereof.

Claims:

We claim:

1. A lightweight composite ballistic armour panel having composite layer made of at least one ceramic layer comprising closely packed ceramic pellets/tiles arranged in between at least two mutually parallel layers of fabric network structure having means, to receive and to hold, plurality of ceramic pellets/tiles wherein said fabric network structure retains the alignment of said ceramic pellets/tiles in a contiguous surface by holding them together and parallel to each other forming the strike face of the designed armour.

2. The lightweight composite ballistic armour panel as claimed in claim 1 wherein the interspatial voids within said ceramic pellets/tiles are filled with adhesive matrix made of either thermoset or thermoplastic nature for holding the pellets/tiles in fixed location whereby diffusing the shock resulting from the impact by nullifying the impact energy through localised fracture of pellets/tiles adjacent to point of impact and restricting the damage by limiting the propagation of crack through discontinuous surfaces of localised fractured pellets/tiles for retaining multi-hit capability of the armour.

3. The lightweight composite ballistic armour panel as claimed in claim 1 wherein each ceramic pellet/tile is provided with at least one slot around the circumference on both, the upper end and lower end wherein said slots facilitate holding and binding of pellets/tiles firmly inside the openings provided on the fabric network structure and keep said pellets/tiles in vertical position by constraining relative motion of said pellets/tiles between said openings on parallel layers of fabric network structure wherein said network structure is made of material selected from group consisting of polymer, elastomer or paper to keep said ceramic pellets/tiles in a uniform arrangement thus improving the flexural stiffness of said ceramic layer and consequentially the ballistic properties.

4. The lightweight composite ballistic armour panel as claimed in claim 1 wherein said ceramic pellets are cylindrical in shape along the vertical axis.

5. The lightweight composite ballistic armour panel as claimed in claim 1 wherein shape of said ceramic tiles is hexagonal, rectangular, pentagonal, triangular, spherical, octagonal or square.

6. The lightweight composite ballistic armour panel as claimed in claim 4 and claim 5 wherein said ceramic pellets/tiles may have convexly contoured upper end and convexly contoured lower end.

7. The lightweight composite ballistic armour panel as claimed in claim 1 wherein said ceramic pellets/tiles comprise at least one material selected from a group consisting of alumina, glass, boron carbide, boron nitride, silicon oxide, silicon nitride, silicon carbide, magnesium oxide, silicon aluminium oxy-nitride or mixtures thereof.

8. The lightweight composite ballistic armour panel as claimed in claim 3 wherein said fabric network structure comprises a uniform mesh having openings either in honeycomb or rectangular pattern wherein said openings are configured to receive and engage said slots provided on said ceramic pellets/tiles.

9. The lightweight composite ballistic armour panel as claimed in claim 3 wherein said network structure is in the form of honeycomb core with uniform openings wherein dimension of said openings in said honeycomb is adapted to receive and tightly engage said pellets/tiles in one place.

10. The lightweight composite ballistic armour panel as claimed in claim 1 wherein said ceramic layer is bound and retained inside said armour panel by fixing it on pressure sensitive adhesive tape from both, the top surface and bottom surface.

11. The lightweight composite ballistic armour panel as claimed in claim 1 wherein on the upper surface of said composite layer, a front entrapment system is bonded to entrap fragments of the damaged ceramic pellets when hit by a projectile and for protecting said armour panel from moisture and water, said front entrapment system further comprises:

a. first layer bonded to the upper surface of said composite layer using thermoset plastic or thermoplastic to keep the ceramic fragments intact within said armour panel after a projectile impact wherein said first layer comprises fibre reinforced composites;

b. second layer bonded to the upper surface of said first layer using adhesive wherein said second layer is made of a material selected from group of aramid fabric, carbon fabric, or equivalent ballistic grade material for front entrapment;

c. third layer bonded to the upper surface of said second layer using elastomeric adhesive wherein said foam layer is preferably made of cross linked polyethylene foam material.

12. The lightweight composite ballistic armour panel as claimed in claim 1 wherein on the back surface of said composite layer, a back spall system is bonded wherein said back spall system further comprises:

a. at least one shock absorbing backup wad layer bonded to the back surface of said composite layer using adhesive for diffusing the shock resulting from the projectiles impact wherein said shock absorbing backup wad layer is made of material selected from group of high performance fiber, fabric, metals, alloys or composites;

b. at least one spall layer bonded to the back surface of said shock absorbing wad layer using elastomeric adhesive wherein said spall layers are made of materials selected from group of aramid fabric, carbon fabric or equivalent ballistic grade materials.

13. The lightweight composite ballistic armour panel as claimed in claim 1, claim 11 and claim 12

wherein all the layers in said armour panel are wrapped in polyurethane coated nylon fabric layer using the elastomeric adhesive.