Light weight composite armor with structural strength

Abstract

Future fighting vehicles will require lighter, stronger and more space efficient armor for better protection, better survivability and better mobility.

The invented lightweight armor component consists of armor-grade material (2), such as ceramic, encapsulated in fiber reinforced cementitious composite (FRCC) (1). The encapsulation FRCC pre-stress the armor-grade material.

The resulting armor component of the present disclosure provides excellent ballistic protection against most types and sizes of Kinetic Energy (KE) threats and Chemical Energy (CE) threats.

The armor component has low areal density, reduced damage area, improved multi-hit capability, flexible design and also provides high structural strength. It furthermore has the advantage, that it can be formed in virtually any shape.

The present disclosure results in superior ballistic characteristics of an armor component. An object of the present disclosure is to increase penetration resistance of especially ceramic based armor, while lowering system weight.

Description

FIELD AND BACKGROUND OF THE INVENTION[0001]The present disclosure relates generally to passive ballistic armor for military and civilian use, and in particular, to lightweight composite armor structure with very strong structural strength based on a multi-material composite for absorbing and limiting the transfer of impact energy from most types and sizes of kinetic energy (KE) threats and chemical energy (CE) threats.[0002]The present disclosure relates especially to ballistic protection for use in military vehicles of different types and other moving and stationary military platforms, or for use in permanent or temporary protection of different types in buildings or other fixed or mobile installations. The ballistic protection according to the present disclosure can be employed as protection against different types and sizes of low-velocity or high-velocity armor ballistic threats, such as armor piercing projectiles or threats based on chemical energy.[0003]It is an object of the ...

AI Technical Summary

Benefits of technology

[0114]Studies shows that better confining of armor-grade ceramic results in an increase in penetration resistance, and that ceramic yields much higher performance when their boundaries are heavily encapsulated, because if the ceramic material is not encapsulated, the fractured pieces can move away easily, and residual protection is lost. The type of encapsulation can influence the ballistic efficiency of the ceramic based armor, and that “dwell” type defeat of penetrators can be achieved on the ceramic front surfaces. Two key parameters here are suppression of cracked tile expansion and putting the ceramic in an initial state of high compressive stress to delay or stop it from going into a state of tensile stress during impact. Tensile stresses are the cause of the premature failure in ceramic components, since in general ceramic have higher strength in compression than in tension.

[0115]The advantage of such compressive stresses on ceramic component is two-fold. First, the ceramic material will have a higher tensile strength and will be more effective in defeating the projectile, as the projectile will spend more time (and more energy) before it causes the ceramic component to develop cracks and failure. This can allow the disclosed composite structure to defeat projectiles with minor damage to the ceramic component, and therefore will allow the structure to take multiple hits. The ceramic component can be preserved due to the relative high elastic strain limit of cementitious composites. Even though the effectiveness of the system will be reduced (in the case of formation of cracks in ceramic), the remaining compressive stresses will maintain some effectiveness of the ceramic for subsequent hits, and at the minimum will keep the un-cracked portion of ceramic in place to defeat the projectile and dissipate its energy. Yiwang Bao etal (materials letters December 2002) reported substantial enhancement in projectile penetration resistance in encapsulated and pre-stressed ceramic material, and experimental results by Holmquist and Johnson (EDP Sciences 2003) also shows that pre-stressed ceramics does improve performance. Other sources shows that three dimensional stressing of ceramic provides a higher enhancement in the penetration resistance than a two dimensional stressing. There is a clear need to improve the impact and penetration resistance, ballistic efficiency and structural integrity of ceramic armor employed on a widespread basis in many types of armor systems. Over about the past twenty years, it has been discovered that the ballistic performance of ceramic armor is critically dependent on the specific design attributes and geometrical configuration of the entire armor system. In particular, it has been observed that enhanced destruction and fragmentation of an incoming projectile can be obtained by increasing the so-called “dwell” time of the projectile on the front face of the ceramic armor during the very early stages (the first 5-10 microseconds) of the ballistic impact event.

[0116]“Dwell,” the duration of projectile erosion without target penetration, is an indicator of the ceramic's ballistic efficiency. Strategies to prolonging projectile dwell on ceramics include retarding damage and retaining dynamic toughness in the damaged state. Ceramic failure caused by excessive structural bending from ballistic loading is another possible limiting factor to improving ballistic performance. Improving ceramic armor can be obtained with improved structural support for the ceramics. Desirable attributes of a backing material include shock mitigation and high stiffness to resist bending.

Problems solved by technology

Facial ceramics are most effective in this type of application, but have limited fracture toughness and damage tolerance; thus the ceramic is parasitic to the vehicle structure.

However, they have a large weight penalty and are not as efficient at stopping armor-piercing threats.

Ceramics are extraordinarily hard, strong in compression, light weight and brittle, making them efficient at eroding and shattering armor-piercing threats, but not as effective at withstanding multiple hits.

This decreases the ability of the projectile to defeat the armor system.

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