Lightweight transparent armor window

Abstract

The invention relates to a lightweight transparent armor laminate comprising layers of borosilicate glass, layers of transparent glass-ceramics and a polymer spall layer of polycarbonate and / or polymethyl methacrylate. The layers are bound by polyurethane and / or polyvinylbutyral interlayer films.

Description

[0001]This application claims the benefit of the filing date of U.S. Provisional Application Ser. No. 60 / 975,661 filed Sep. 27, 2007.[0002]Commercially available, glass-based transparent armor typically consists of multiple glass and polymer layers, which are laminated together to form a relatively thick composite. The resulting composite must be transparent and essentially free of optical distortion while providing maximum protection against ballistic impact of projectiles and fragments at minimum weight and minimum cost. Of particular interest are transparent laminates, which restrict the destruction caused by the projectile locally to ensure maximum residual vision and provide protection against multiple hits.[0003]To successfully stop a projectile, impact resistant transparent laminates typically engage various defeat mechanisms, including projectile fragmentation and mass removal by projectile erosion. Systems employing transparent ceramic materials such as, for example, transp...

AI Technical Summary

Benefits of technology

[0002]Commercially available, glass-based transparent armor typically consists of multiple glass and polymer layers, which are laminated together to form a relatively thick composite. The resulting composite must be transparent and essentially free of optical distortion while providing maximum protection against ballistic impact of projectiles and fragments at minimum weight and minimum cost. Of particular interest are transparent laminates, which restrict the destruction caused by the projectile locally to ensure maximum residual vision and provide protection against multiple hits.

[0008]Present State-of-the-Art glass-based systems provide single-hit protection against armor piercing projectiles (STANAG Level 3 or similar) at oblique impact at areal densities of about 30 psf. In comparison to other glass-based impact-resistant laminates, the designs disclosed provide multi-hit protection against 0.30 cal. AP-M2 or similar projectiles at impact speeds of up to 2750 fps at a thickness of less than 80 mm and an areal density of less than 30 psf. Single-hit protection against the same threat is achievable at an areal density of less than 25 psf by removing one of the glass ceramic layers. The composites are useful, for example, as transparent armor structures in military and security vehicles as well as for windows in secured buildings applications.

[0012]All laminate layers are joined together with polymer interlayers. Each interlayer may range from about 10 to 80 mil thick in the finished laminate. Most preferably the polymer interlayer is polyurethane or polyvinylbutyral. Select interlayers may be reinforced, for example by incorporating a tear-resistant PET film. Optionally, a thin glass layer may be laminated to the backside of the spall layer to protect the polymer surface against degradation including scratches and chemical attack by window cleaning agents.

Problems solved by technology

Systems employing transparent ceramic materials such as, for example, transparent spinel, sapphire, or AlON, show superior ballistic performance over traditional glass-based systems, but are often not available in larger sizes and volumes.

Currently, the cost per square inch for these systems is typically more than 5 times higher than for glass-based systems offering comparable protection.

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