Patent Abstract:
A non-metallic armor structure having lightweight and being capable of withstanding multiple impacts without substantial degradation of the penetration resistance of the armor.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This utility patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/081,075 filed Jul. 16, 2008, entitled “Composite Armor Structure,” the entire disclosure of the application being considered part of the disclosure of this application, and hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to armor used for preventing the penetration of structures by projectiles. More specifically, the invention relates to an improved armor including a fiber grid structure having composite tiles, such as composite ballistic resistance tiles retained in the grid with the grids forming a substantially polyhedron structure that both increases the resistance to penetration as well as increases the performance of each individual composite tile. 
         [0003]    Armor systems have traditionally been known to include thick metal as an outer skin to protect the structure or vehicle. Typically, these armor structures such as those used in military vehicles include layers of thick metal plates to provide resistance to the penetration of projectiles. The resistance to penetration of projectiles is very important to protect individuals inside from injury and death. Newer types of armor piercing projectiles have decreased the efficiency of metal plates in preventing projectile penetration and metal armor systems are extremely heavy, which detracts from the performance and fuel economy of mobile vehicles. The heavy weight of metal-plated armor causes many problems including limited vehicle speed, high fuel consumption, increased time for vehicle assembly, as well as detracting from the maneuverability and other operational capabilities of the vehicle. To summarize, the weight of the layered metal plates causes serious reductions in performance capabilities of any vehicle to which the armor system is added. For example, increased fuel consumption due to the heavy weight of the metal plates requires more frequent fill-ups and reduces the range of the armored vehicle. In addition, increased fuel consumption creates other problems in a military environment, such as requiring more trips to the armored vehicles by fuel tanker trucks, which are typically not armored. These fuel tanker trucks during a military operation are common targets as the armored vehicles stop operating if fuel is unable to reach them, and therefore improving the fuel economy of armored vehicles is important. In addition, the additional weight of the vehicle from the armor, when used in a military environment may seriously reduce the operating performance and characteristics of the vehicle. For example, certain vehicles when armored are incapable of traveling across some off-road terrains. 
         [0004]    To address some of the above deficiencies with metal-plated armor, some manufacturers have replaced metal armor with lighter weight armor systems made from composite material having reinforced fibers made of, for example, Kevlar, S-2 glass, graphite, or high molecular weight polyethylene. Such armor systems have utilized these multiple layers of composite materials to achieve reduced overall weight, while yet providing sufficient structural properties that preserve the ability of the armor to protect against penetration. Many times these composite armor materials are used in combination with metal plates and can provide additional protection while yet reducing weight. It is still desirable to reduce the weight of the vehicle while yet improving the resistance of the armor to projectile penetration. These systems are very expensive and generally do not provide the desired balance between weight, cost and effectiveness. 
         [0005]    Other armor systems have been designed that use ceramic tiles in connection with a grid to provide protection against high speed projectiles while yet minimizing the weight of the armor system. Ceramic tiles are much lighter than metal plates. Many ceramic tiles have convex surfaces and are inserted into a honeycomb grid. Upon impact by the projectile against the ceramic tiles, ceramic armor systems are known to experience failure of not only the impacted plate but also of the plates adjacent to the plate receiving the impact. Therefore, it is critical but also difficult to manage the propagation of cracks from the plate receiving the impact to adjacent plates. Ceramic tiles also typically lose structural integrity after an initial impact, making the armor system vulnerable to subsequent impacts. 
         [0006]    The armor system must sustain multiple hits by projectiles to sufficiently protect the occupants of a vehicle. As stated above, many ceramic systems provide excellent resistance to projectile penetration against the first impact but their effectiveness is typically substantially reduced for subsequent impacts. Some manufacturers have proposed layering on top of each other multiple layers of ceramic tiles similar to the layers of metal plates previously used as well as providing layers of composite materials in combination with the ceramic tiles. These layers of composite materials are generally sheets such as sheets of carbon fiber directly engaging the ceramic tiles. While these multiple layered ceramic tiles provide additional protection, they also substantially increase the weight of the vehicle while yet experiencing propagation of cracks and debris created during impact. Propagation of cracks weakens the adjacent composite plates as well as the underlying plates. The propagation of such cracks results from the tight engagement of the armor structure and therefore while multiple layers of ceramic tiles do provide additional protection, the armor system may after an initial impact be substantially weakened against subsequent impacts. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a composite armor that improves the resistance to penetration of projectiles as well as resistance to projectile penetration from multiple impacts, while reducing the weight of the armor structure as compared to metal plate systems and other armor systems with similar penetration resistance. 
         [0008]    More specifically, the armor system of the present invention provides a polyhedron structure which covers the surface on which armor protection is needed. The polyhedron structure is made up of a plurality of cellular structures into which composite inserts are provided. Cellular structures generally are generally a one-piece integrally formed continuous composite cellular structure of which multiple cellular structures are used to create the polyhedron structure. A filler such as a ballistic foam is provided within the polyhedron structure formed by the cellular structures. If needed, various composite laminates may be provided to provide additional protection. 
         [0009]    Further scope and applicability of the present invention will become apparent from the following detailed description, claims and drawings. However, it should be understood that the specific examples in the detailed description are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which: 
           [0011]      FIG. 1  is a perspective view of a cellular structure; 
           [0012]      FIG. 2  is a plan view of the cellular structure; 
           [0013]      FIG. 3  is a perspective view of cellular structures forming the inter-disposed sides; 
           [0014]      FIG. 4  is a plan view of a first exemplary side in  FIG. 3 ; 
           [0015]      FIG. 5  is a plan view of a second exemplary side in  FIG. 3 ; 
           [0016]      FIG. 6  is an exploded perspective view of an exemplary polyhedron structure; 
           [0017]      FIG. 7  is an exploded perspective view of a second exemplary polyhedron structure; 
           [0018]      FIG. 8  is an exploded perspective view of a third exemplary polyhedron structure; 
           [0019]      FIG. 9  is an exploded perspective view of a fourth exemplary polyhedron structure; 
           [0020]      FIG. 10  is an exploded perspective view of a fifth exemplary polyhedron structure; 
           [0021]      FIG. 11  is an exploded perspective view of a cellular structure without composite inserts; 
           [0022]      FIG. 12  is an exploded perspective view of a cellular structure partially assembled to form the polyhedron structure; 
           [0023]      FIG. 13  is a perspective view of the grid polyhedron cellular structure; 
           [0024]      FIG. 14  is a perspective view of the cellular structure with composite plates in place and forming the polyhedron structure; 
           [0025]      FIG. 15  is a perspective view of the polyhedron structure as complete with a portion of the sides removed to show the various layers; 
           [0026]      FIG. 16  is a perspective view of the polyhedron structure; 
           [0027]      FIG. 17  is an exploded partial perspective view of an exemplary polyhedron structure; 
           [0028]      FIG. 18  is an enlarged perspective view of the polyhedron structure showing the various layers of laminate; 
           [0029]      FIG. 19  is a two-layer polyhedron structure showing the cellular structures without composite inserts and with the sides exploded off to show the inner portions; 
           [0030]      FIG. 20  is a perspective view of an assembled two-layer cellular structure; 
           [0031]      FIG. 21  is a perspective view of the polyhedron structure with portions removed to show the inner foam; 
           [0032]      FIG. 22  is a perspective view of the cellular structure with inserted ceramic tiles forming the polyhedron structure; 
           [0033]      FIG. 23  is a perspective view of a completed polyhedron structure; 
           [0034]      FIG. 24  is an exemplary side view of a two-layer polyhedron structure; 
           [0035]      FIG. 25  is a side view of the two-layer polyhedron structure in  FIG. 24  with ceramic tiles partially in place and partially removed; 
           [0036]      FIG. 26  is a perspective view of a three-layer polyhedron structure showing the grid of the cellular structures; 
           [0037]      FIG. 27  is a perspective view of the polyhedron structure with ceramic tiles in place; 
           [0038]      FIG. 28  is a perspective view of the polyhedron structure; 
           [0039]      FIG. 29  is a side view of the polyhedron structure in  FIG. 27  with ceramic tiles partially in place and partially removed; 
           [0040]      FIG. 30  is another exemplary side view of the polyhedron structure in  FIG. 27  with the ceramic tiles partially in place and partially removed; 
           [0041]      FIG. 31  is a perspective view of a four-layer polyhedron structure showing the grid of the cellular structure; 
           [0042]      FIG. 32  is a first exemplary side view of a four-layer polyhedron structure; 
           [0043]      FIG. 33  is a second exemplary side view of a four-layer polyhedron structure; 
           [0044]      FIG. 34  is a perspective view of an exemplary two-layer polyhedron structure using rectangular side plates; 
           [0045]      FIG. 35  is a perspective view of the polyhedron structure in  FIG. 38  with the ceramic tiles inserted; 
           [0046]      FIG. 36  is a completed perspective view of the polyhedron structure in  FIGS. 34 and 35 ; 
           [0047]      FIG. 37  is a perspective and top plan view of a hexagonal grid element; 
           [0048]      FIG. 38  is a perspective and top plan view of a triangular grid element; 
           [0049]      FIG. 39  is a perspective and top plan view of a trapezoidal grid element; 
           [0050]      FIG. 40  is an exemplary illustration of an armored vehicle; 
           [0051]      FIG. 41  is a perspective view of a two-layer cellular structure wherein the grids are offset relative to each other; 
           [0052]      FIG. 42  is a top plan view of a two-layer cellular structure wherein the grids are offset relative each other; and 
           [0053]      FIG. 43  is a side view of a two-layer cellular structure wherein the grids are offset relative to each other. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0054]    The present invention is directed to an armor system  10  such as for the exemplary vehicle  110  illustrated in  FIG. 40 . The armor system  10  is partially illustrated in  FIGS. 1-39  as being formed from individual polyhedron structures  20 . The individual polyhedron structures  20  are generally illustrated in greater detail in  FIGS. 1-39  and multiple structures of varying sizes may be required to sufficiently armor a vehicle. More specifically, the multiple polyhedron structures  20  creates individual cells that combine to form the armor system  10 . Therefore, for the exemplary vehicle  110  illustrated in  FIG. 40 , the polyhedron structures  20  would preferably substantially cover the vehicle. To conform the armor system  10  to the vehicle, the structure of the individual polyhedron cells  20  may vary to match the contour of the vehicle. However, to reduce manufacturing costs, it is preferable to use standardized polyhedron structures whenever possible, which can be formed in single or multiple sizes to form the armor system. Therefore, the armor system  10  will be described below as being formed of multiple polyhedron structures  20 , even though other shapes may be used having a cavity that is filled with a filler  100 , such as ballistic foam. 
         [0055]    The polyhedron structures  20  are generally formed of a grid of cellular structures  22 . The individual cellular structures  22  may combine to form a cellular structure  30  that forms the outer surface to which laminates  80  are applied. As more specifically illustrated in  FIG. 6 , the cellular structure may be formed from a first face  32 , a second face  34  and inter-disposed cellular sides  50 . As further illustrated in  FIG. 19 , the cellular structure  30  may further include at least one cellular structure  40 . These at least six cellular structures  22 , forming the outer cellular structure  30  specifically the two faces  32 ,  34  and four sides  50 , form a cavity into which the filler  100  is placed. The cellular structures  22  forming the outer cellular structure  30  as well as any secondary or inner cellular structures  40  or side cellular structures  50  each include a grid  38  that defines openings  36 . The openings  36  are configured to receive composite inserts  70 . The grid  38  extends to a border structure  39 . Due to the overall size of the cellular structures  22 , the grid  38  may have partial openings  37  near the border  39 . These partial openings may be filled with different shaped or partial composite inserts  70 . 
         [0056]    It is preferable for the strength and integrity of the cellular structure  30  that the grid structure  38  of the sides  50  meets the grid structure  38 , of the cellular faces  32 ,  34  structure, and if present any additional inner cellular structures  40 . More specifically, the points where the grid structure  38  meets the border  39  are approximately aligned for all of the cellular structures  22 . This allows the composite inserts  70  to individually support an adjacent plate and minimizes the potential for propagation of cracks from an insert  70  on the cellular structure faces  32 ,  34  to an insert  70  or in particular multiple inserts on the sides  50 . As illustrated in the side views of other Figures, the sides within a single cellular side structure may differ, such that they match the edge pattern of one of the exterior cellular structure faces  32 ,  34 . 
         [0057]    Composite inserts  70  generally include a perimeter portion  72  and a first side  74  and a second side  76 . Composite inserts  70  are inserted into the cellular structures  22  and in particular, into the openings  36  defined by the grid structure  38 . The composite inserts  70  may be formed in triangle shapes  60 , partial hexagon shapes  62 , hexagon shapes  42 , rectangular or square shapes  64  or any other desired shapes. 
         [0058]    The armor system  10  further includes laminates  80  which are secured to the cellular structures  22  and the composite inserts  70 . The laminates  80  are generally secured to the cellular structure  30  as well as the inner cellular structures  40  but in the preferred embodiment are not secured to the inter-disposed sides  50 . While laminates  80  secured to the inter-disposed sides  50  would improve protection against projectile penetration, the laminates  80  are generally expensive and would not provide a substantial increase in protection. The laminates  80  are generally secured with the use of a binding material such as a resin to the cellular structures  22 . The bonding material may also be used as a filler applied to the inserts  70  and in some cases around the perimeter portion  72  to fill in the gaps between the inserts  70  and the grid structures  38 . The binder may also bind the sides  50  to the other cellular structures  30  and  40 . 
         [0059]    Laminates  80  can be formed from any material that improves the penetration resistance of the armor and more particularly, improves the resistance of the composite inserts  70  against penetration. The laminates  80  are generally shown in the Figures as being placed on at least one side of the cellular structures  22  forming the polyhedron structures in particular the exterior surfaces however, as seen in other Figures, the laminates  80  may be layered on each side of the cellular structures  22  or selectively layered to maximize resistance to penetration balanced against cost. In general, the armor  10  illustrated in the Figures uses at least two layers of laminates  80  in particularly a first layer  82  formed of a carbon fiber reinforced polymer which generally forms the exterior surface of the polyhedron structure  20  and a second layer  84  of a hybrid ductile fabric which generally engages directly against the composite inserts  70 . In some cases, the binder although not illustrated may be inter-disposed between the second laminate layer  84  and the composite inserts  70 . In the preferred embodiment, the exterior surface of the polyhedron structure on at least one side includes four layers of laminates particularly the first and second layers  82  and  84  layered in an alternating manner specifically including extending away from the cellular structure  22 , the hybrid ductile fabric lamina  84 , high modulus lamina  82 , hybrid ductile fabric  84 , and high modulus lamina or carbon reinforced polymer  82 . In the preferred embodiment, it has been found that materials having acoustic impedance between 0.7×10 6  and 40×10 6  kg/m 2 , as measured in a direction parallel to the normal of the laminates sheets are most effective. It should be appreciated and as disclosed in the Figures, various configurations and placements of laminates  80  may be used with the armor system  10 . Adding the laminates  80  generally improves the strength against projectile resistance. Also, though not illustrated, the cellular structures  22  may form a polyhedron structure  20  with each cellular structure  22  having composite inserts being directly laminated together or laminated together with the laminates  80  inter-disposed between. 
         [0060]    As further illustrated in the Figures specifically  FIGS. 19-36 , the polyhedron structures  20  may be stacked to create two, three or more layers with filler between. It is expected as shown in the Figures that for the stacked polyhedron structures  20  that only one cellular structure  40  would be placed between each filler  100  to reduce costs, although individual polyhedron structures  20  that form by itself one layer of armor may be stacked such that the cellular structures  22  with composite inserts  70  inserted in close proximity with no filler therebewteen. The sides  50  may be formed from multiple sides in stacked configuration as illustrated in the Figures, or one side cellular structure (not illustrated), extending past the inner cellular structure  40 . 
         [0061]    The composite inserts  70  may be made of materials such as ceramic, glass, metal matrix, ceramic matrix composite, or any other types of composite materials known to provide high resistance to impact penetration while providing low weight, particularly when compared to metal armor systems. The surfaces of the composite inserts  70  may vary such as having convex or concave surfaces. In addition to the other shapes described above, the composite inserts  70  may be provided in square, oval, round, or other shapes. 
         [0062]    The cellular structures  22  may be formed in a variety of configurations but preferably use the cellular structures as described in U.S. patent application Ser. No. 11/504,343 filed on Aug. 15, 2006. Such cellular structures minimize crack propagation from a projectile impact. As described in U.S. application Ser. No. 11/504,343, the cellular structures may be formed from individual fibers that extend approximately continuous throughout the cellular structure. Of course, other fiber structures may be used without continuously extending fibers. 
         [0063]    The filler within the polyhedron structure  20  is generally illustrated as  100  and is typically a ballistic foam or another type of lightweight filler material that is resistant to projectile penetration. The filler  100  also helps to support the composite inserts after impact from a projectile such that the initial impact of a projectile, even if it cracks the outer layer of composite inserts near the impact zone, does not completely or substantially reduce subsequent performance to additional impacts. By separating the composite inserts  70  on the cellular structure  30  with the filler  100  from the second layer of ceramic inserts shown as being inserted in the grid  40 , the armor system  10  may withstand subsequent impacts from projectiles without being compromised. In addition, using a filler  100  such as a ballistic foam further increases the ability of the armor system  10  to withstand against subsequent projectile impacts. 
         [0064]    The cellular grid structures  22  in particular the cellular structures  30 ,  40  and  50  of are generally also assembled as described in U.S. patent application Ser. No. 11/504,343 filed on Aug. 15, 2006. Once the individual cellular structures  22  are assembled, the polyhedron structure  20  is then assembled out of the cellular structure  30 , second cellular structure  40  as well as the inter-disposed sides  50 . After it is assembled into a polyhedron structure, the filler or ballistic foam  100  is inserted into the cavity of the polyhedron structure  20 . In some embodiments, the polyhedron structure  20  may be assembled except one side  50  or one of the outer cellular structures  30  or  40 , to allow for easy insertion of the filler  100 . In other embodiments, the cellular structures  22  may be assembled but for at least one composite insert which is inserted later. To assembly multi-layer polyhedron structures, the cellular structures  22  are assembled as described in U.S. patent application Ser. No. 11/504,343 and then assembled into the polyhedron structure  20 . Once the ballistic foam or filler  100  is inserted into the polyhedron structure  20 , the polyhedron structure easily maintains its shape for assembly onto the armor system of a vehicle  110 . The polyhedron structure  20  may be a cuboid, a rectangular box, a hexahedron, an octagonal prism, an elongated pentagonal cupola as well as any other desirable shape. As illustrated in  FIG. 40 , it is assembled on the vehicle  110 , the cellular structure  102  having composite inserts  104  is shown in use for the floor plan  107  of a military vehicle  109 . It should be appreciated that the cellular structure  102  can be assembled adjacent to each other and throughout the entire floor plan or across the entire outer surface of the vehicle. The illustrated vehicle and shape is only an exemplary embodiment and it may be used on a variety of other vehicles as well as stationary objects such as buildings and bunkers. Forming large polyhedron structures allows for lightweight building blocks to be created from which buildings may be quickly assembled for use in field operations where danger exists from projectiles. Therefore, the polyhedron structures can be transported as lightweight, easily assembled building blocks that quickly create an armored bunker structure for forward field operations. The structure would provide resistance against impact such as from mortar rounds, small arms fire, rocket propelled grenades and other projectiles. Of course, modifications can be made to the polyhedron structure  20  in particular the cellular structures  22  to provide attachment means to quickly connect the polyhedron structures together in a desired building shape. 
         [0065]    As illustrated in  FIGS. 41-43 , the cellular structures  22  may be place din an offset grid  38  pattern. More specifically, when the cellular structures forming one portion of the overall cellular structure  30 , may be placed together and have the grids offset, such that the grid of one structure  22  does not align with the grid of other cellular structures. Therefore, a projectile that hits the grid  38  of the outermost cellular structure, the weakest portion of the cellular structure will most likely hit a ceramic tile  70  of the underlying structure and not the grid of the underlying cellular structure. Of course, although the cellular structures are illustrated as being laminated or adjoining, ballistic foam  100  or other laminates may reside therebetween to provide enhanced resistance to projectile penetration. 
         [0066]    The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.

Technology Classification (CPC): 5