FORMABLE ARMORS USING CERAMIC COMPONENTS

Abstract

A formable armor that resists penetration by impacting projectiles. The instant formable armor features a plurality of cylindrical ceramic barrels each having flat ends that fay with the flat surfaces of adjacent ceramic barrels. Rows of faying cylindrical barrels are disposed parallel to one another. The substantially parallel rows of cylindrical ceramic barrels are affixed to a backing layer that maintains continuous contact between adjacent cylindrical barrels.

Claims

1. A formable armor that resists penetration by impacting projectiles, comprising: a plurality of cylindrical ceramic barrels each having a flat surface on opposing end surfaces, said cylindrical ceramic barrels faying on at least one flat surface, said plurality of cylindrical ceramic barrels faying on at least one flat surface disposed into at least two substantially parallel rows of cylindrical ceramic barrels, said substantially parallel rows of cylindrical ceramic barrels affixed to a backing layer that maintains continuous contact between adjacent cylindrical barrels.

2. The formable armor of claim 1, in which the cylindrical ceramic barrels are substantially encapsulated by a material having a density exceeding 5 grams per cubic centimeter.

3. The formable armor of claim 1, in which the cylindrical ceramic barrels are affixed to the backing layer by an organic resin.

4. The formable armor of claim 1, in which the backing layer and means of affixing the cylindrical ceramic barrels to the backing layer comprise a cermet.

5. The formable armor of claim 1, in which a frontal surface layer is affixed to the plurality of cylindrical ceramic barrels on the surfaces opposite to the backing layer, said frontal surface layer comprising a material having a density exceeding 2 grams per cubic centimeter.

6. The formable armor of claim 1, in which ceramic separator components are disposed between the curved surfaces of adjacent cylindrical ceramic barrels, said ceramic separator components each having a flat surface on opposing surfaces, a groove on opposing curved surfaces, and a maximum dimension between curved surfaces at least equal to the diameter of the cylindrical ceramic barrels.

7. The formable armor of claim 3, in which the backing layer and means of affixing the cylindrical ceramic barrels comprise the same organic resin.

8. The formable armor of claim 6, in which the faying surfaces of the ceramic separator components and contiguous cylindrical ceramic barrels are substantially serrated.

9. The formable armor of claim 6, in which the cylindrical ceramic barrels and ceramic separator components are encapsulated in a material having a density exceeding 5 grams per cubic centimeter.

10. The formable armor of claim 6, in which a hole is formed perpendicular to the flat surfaces of the ceramic separator components and a round core component faying with the surfaces of said hole formed perpendicular to the flat surfaces of the ceramic separator component, said round core component having a density at least that of the ceramic separator component.

11. The formable armor of claim 10, in which the round core component is tubular.

12. The formable armor of claim 10, in which the round core component extends through the holes of at least two contiguous ceramic separator components.

13. The formable armor of claim 12, in which the round core components extending beyond the holes of the outermost ceramic separator components are affixed within a frame enclosing the ceramic components.

14. The formable armor of claim 13, in which the frame affixing the round core components extending beyond the holes of the outermost ceramic separator components substantially comprises an organic resin.

15. The formable armor of claim 14, in which the backing layer and frame affixing the round core components substantially comprising an organic resin are formed together through a resin infusion process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 is an isometric view that shows the basic embodiment of the formable armor using cylindrical ceramic shapes affixed to a backing layer.

[0039] FIG. 2 is an isometric view that illustrates an alternative embodiment of the formable armor.

[0040] FIG. 3 is an isometric view that depicts a preferable alternative embodiment in which ceramic separator components 80 having grooves on opposite surfaces are disposed between contiguous cylindrical ceramic barrels.

[0041] FIG. 4 is an isometric cutaway view that illustrates a further preferable alternative embodiment in which optional round core components 90 are placed in round holes 93 of ceramic separator components.

MODES FOR OPERATING THE INVENTION

[0042] The various drawing figures accordingly depict a number of embodiments according to the present invention. The embodiments are summarized below. A more detailed description of the respective figures follows.

[0043] FIG. 1 shows the basic embodiment of the formable armor using cylindrical ceramic shapes affixed to a backing layer. The formable armor 10 comprises a plurality of cylindrical ceramic barrels 20. The cylindrical ceramic barrels in this embodiment are disposed in rows with collinear principal axes perpendicular to the flat ends 24 of each barrel. The cylindrical ceramic barrels are affixed to a backing layer 30. The planes of the flat ends may, but need not be, parallel. Cylindrical ceramic barrels may, but need not be, the same length.

[0044] FIG. 2 illustrates an alternative embodiment of the formable armor. A groove 44 is present on the curved surface of each cylindrical ceramic barrel. Grooves are parallel to the axis of the cylindrical barrel. Optional thin metal layers 50 are depicted on the surfaces of grooves in this illustration. Such thin metal layers may be bonded to one or both contiguous components with an adhesive 55 or alternatively deposited by spraying or dipping in molten metal. The interstices or spaces between the ceramic components and backing layer in this figure are filled by an optional resin 60. An optional frontal layer 70 is affixed to the formable armor.

[0045] FIG. 3 depicts a preferable alternative embodiment in which ceramic separator components 80 having grooves on opposite surfaces are disposed between contiguous cylindrical ceramic barrels. Ceramic components may further resist relative displacements by means of an adhesive 83. The surfaces of cylindrical ceramic barrels and ceramic separator components may be smooth. Alternatively, cylindrical ceramic barrels and ceramic separator components may have multiple serrations 86 on faying surfaces. Serrations serve to resist relative displacement.

[0046] FIG. 4 illustrates a further preferable alternative embodiment in which optional round core components 90 are placed in round holes 93 of ceramic separator components. The round core components in this figure are depicted as protruding beyond the surfaces of the outermost ceramic separator components and embedded in an optional resin frame 100. A portion of the resin frame is removed in this illustration to show the ends of ceramic separator components and round core components.

Advantages

[0047] The invention offers numerous alternatives for a person skilled in the art to design composite armors that could form curved surfaces while being thinner and lighter than those produced using the present art. Through the present invention one skilled in the art can add one or more reinforcing layers, including metal and ceramic armor plates. Importantly, composite armors made with any of embodiments of the present invention, whether flat or curved, will have a continuous layer of ceramic components of almost constant thickness. This constant thickness ensures that there are no weak locations through which impacting projectiles can easily penetrate. Smaller individual ceramic components ensure that damaged zones remain limited, enabling the formable armors to withstand multiple projectile impacts in a small area.

[0048] This advance in capability would make protection against projectiles possible in many applications where weight and space limitations for would render such protection impossible through the current art. The invention makes possible capabilities now that are not possible currently using existing materials, and can utilize new materials yet to be developed.

Operation

[0049] The formable armor, such as that shown in FIG. 1, becomes operable when a projectile impinges on the first surface of the composite armor. The first surface, or strike face, in the basic embodiment will be a cylindrical ceramic barrel. In alternative embodiments, an impinging projectile will strike either a ceramic component or the optional front layer.

[0050] In the basic embodiment of the formable armor, projectile impact transmits a pressure wave that travels through the cylindrical ceramic barrel. When the pressure wave reaches the surface of the cylindrical ceramic component away from the impact point, part of the momentum and part of the kinetic energy of the projectile is transmitted into contiguous cylindrical ceramic barrels. Energy and momentum transfer is then further dissipated to other components comprising the armor. A compressive wave will be reflected back from the surface into the ceramic component impacted by the projectile. When a layer having higher impedance than the ceramic component is present on the surface, the compressive wave will be stronger.

[0051] For projectile impacts at velocities exceeding 500 meters per second, the intense compressive stresses generated by impact typically produce a region of severe damage in ceramics. This shattered zone forms roughly one projectile diameter beneath the point of impact.

[0052] For projectile diameters in the range of 7.62 millimeters to 15 millimeters, the damage zone will form from 5 to 10 millimeters deep. Microcracks are developed in the damage zone that will propagate through the ceramic material and form larger cracks. Crack propagation velocity is typically 8 to 10 millimeters per microsecond (Strassberger et al, 2002). Crack propagation velocity is similar to the speed of the shock wave transmitting through the damaged ceramic.

[0053] When the shock wave generated by projectile impact reaches an interface with a material of lower impedance, such as air, adhesives, or organic resins, a relaxation wave is produced. This relaxation wave reflects back into the damaged ceramic. The relaxation wave reduces the compressive stress across crack interfaces and may produce a tensile stress. The reflected relaxation wave-thus allows damaged ceramic material to dislocate or spall. When the relaxation wave reaches the impact surface, general failure of the ceramic occurs. Once this happens, the projectile can then easily move through the failed ceramic material.

[0054] The present invention prevents general failure from developing. This happens because compressive waves are reflected at the interfaces with contiguous components before relaxation waves can reach incipient cracks. By maintaining high compressive pressures on crack surfaces, friction forces are strongly increased along crack interfaces. These forces resist crack extension.

[0055] Compressive stresses are maintained for long periods because compressive waves are continuously generated through the present invention along the curved surfaces of cylindrical ceramic barrels. The use of optional grooves, ceramic separator components, high-impedance interface materials, and round core components in ceramic separator components generate more intense compressive waves that form sooner. From these many contributions to forming and sustaining high compressive stresses in incipient cracks, ceramic armor components can stop projectiles more efficiently, and stop more energetic projectiles with the same mass of ceramic through the present invention than is possible with armors made with the present art.

[0056] Use of the optional frontal layer can be used to make the present invention even more efficient. Use of cermets as either frontal layer, backing layer or to fill interstices between ceramic components and the planar components can improve resistance of the formable armor even more. Curvature of the backing layer and radii of the ceramic components can be utilized by a person skilled in the art to further enhance performance of the present invention.

[0057] Use of round core components in ceramic spacer components is particular desirable for stopping blunt or large projectiles. Ceramics are especially vulnerable to blunt projectiles because the damage zone is wide. More ceramic area is subjected to severe compressive stresses upon impact by blunt projectiles. Large projectiles are similarly destructive in ceramics because more kinetic energy is transferred that adds to crack surface energy. Shock waves from large or blunt projectiles also typically reflect from interfaces faster than occurs for small or pointed projectiles. This causes general damage to develop sooner within the ceramic, thus allowing faster penetration by projectiles. The use of round core components can generate compressive waves faster than cracks can propagate, thereby limiting the damaged zones in ceramics even when subjected to large, blunt projectile impacts.

[0058] Location of components that quickly generate compressive stress waves in front of propagating cracks is thus critical. The nearest surface of components such as interface materials having high shock impedance should be within one projectile diameter of another surface having high shock impedance. Projectile diameter should be at least five millimeters but based upon the diameter of the projectile upon which design of the formable armor is based. In no case should the nearest surface having a high shock impedance be more than ten millimeters from the ceramic component surface impacted by a projectile.

[0059] The nearest surface of an interface is determined by either the backing layer, the nearest optional ceramic separator component, the optional round core component used in a ceramic separator component, or encapsulants or coatings on faying surfaces having high shock impedance. When round core components are used in ceramic separator components, the distance between the hole and nearest curved surface is at least three millimeters and not exceeding ten millimeters.

[0060] More than a decade of research has consistently shown that yield strength, ductility, and resistance to penetration by projectiles increase substantially when armor ceramics remain in a state of compression. Conversely, resistance to projectile penetration drops substantially for unconfined, uncompressed ceramics.

[0061] This is why the geometry of the ceramic shapes, the optional use of the ceramic separator component, the optional use of high-impedance materials between the ceramic components, and the optional metal strike face are so important. Among approaches within the current art is to use steel encasement or thin layers of aluminum or plastic encapsulation to provide compression. These materials have a similar or lower shock impedance than projectile metals. Although steel has a relatively high impedance, thick steel layers are not practical to manufacture and add too much weight. Aluminum offers impedance similar to armor ceramics such as silicon carbide and aluminum oxide at typical ballistic impact velocities, but these are inefficient in terms of weight and fabrication cost compared with the present invention. Thin layers of zinc, austenitic stainless steel alloys with chromium concentrations exceeding 17%, copper and nickel reflect much stronger compressive waves into the impacted ceramics than is possible through the current art.

Ramifications and Scope

[0062] Accordingly, the reader will observe that composite armors made through this invention would offer substantial protection against projectiles while allowing such armors to be curved into numerous profiles. Different embodiments of this invention make protection possible against a wide range of projectile sizes and shapes while conforming to the shapes of interior surfaces with a minimum requirement for space. Other embodiments of the present invention can cover curved exterior surfaces without intervening gaps or need for gussets and other supports.

[0063] Many other possibilities exist for a person skilled in the art to use the present invention to produce means of protection against projectiles impacting aircraft, structures, vehicles and people other than those described and illustrated above. The above embodiments are not intended to limit the application of concepts described above.

[0064] Variations and modifications in addition to those described above are believed obvious from the description. Accordingly, the scope of the invention is defined only by the following appended claims that are further exemplary of the invention.