page_title: Bulletproof glass
section_title: Test standards
hierarchical_section_title: Bulletproof glass / Test standards
caption_attribution_description: English: Bulletproof safety glass ballistic test. Layered glass-polymer composite, 55.6mm thick, 116.3 kg/m2, ballistic resistance level 2. From IDET 2007 fair in Brno.
context_page_description: Bulletproof glass is a strong and optically transparent material that is particularly resistant to penetration by projectiles. Like any other material, it isn’t completely impenetrable. It is usually made from a combination of two or more types of glass, one hard and one soft. The softer layer makes the glass more elastic, so it can flex instead of shatter. The index of refraction for both of the glasses used in the bulletproof layers must be almost the same to keep the glass transparent and allow a clear, undistorted view through the glass. Bulletproof glass varies in thickness from ³⁄₄ to 3 ¹⁄₂ inches.
  Bulletproof glass is used in windows of buildings that require such security, such as jewelry stores and embassies, and of military and private vehicles.
context_section_description: Bullet-resistant materials are tested using a gun to fire a projectile from a set distance into the material, in a specific pattern. Levels of protection are based on the ability of the target to stop a specific type of projectile traveling at a specific speed.  Experiments suggest that polycarbonate fails at lower velocities with regular shaped projectiles compared to irregular ones (like fragments), meaning that testing with regular shaped projectiles gives a conservative estimate of its resistance. When projectiles do not penetrate, the depth of the dent left by the impact can be measured and related to the projectile’s velocity and thickness of the material. Some researchers have developed mathematical models based on results of this kind of testing to help them design bulletproof glass to resist specific anticipated threats.
  Well known standards for categorizing ballistic resistance include the following:
  Summary of Euronational (EN) 1063 test conditions in English
  Summary of Underwriter’s Laboratory (UL) ballistic resistance test conditions in English
  Coberturas em Vidro
  U.S. National Insititute of Justice (NIJ) standard for ballistic resistant protective materials (NIJ Standard 0108.01).
caption: Ballistic test of a bullet-resistant glass panel
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