Investigation of the Mechanics of Windborne Missile Impact on Window Glass

Engineers have recognized that failure of the building envelope is one mechanism that can lead to severe damage of structures during windstorms. The building envelope consists of the roof, doorways, windows, and cladding components that form the exterior wall system of a building. Failure of the building envelope results in internal pressurization of the structure which may lead to structural failure. For this reason, engineers have begun to focus on ways to make the building envelope resistant to the effects of severe windstorms. Window glass is one type of cladding material. Of the threats posed by a windstorm, the major threat to window glass consists of windborne debris. ASTM E1886, ASTM E1996, and SSTD 12-99 address the issue of resistance to windborne missile impacts. This thesis concludes that a simple statement of an object's kinetic energy upon impact by itself cannot serve to predict the outcome of the impact. Conservation of angular momentum occurs during a missile impact on window glass. Finally, energy is lost during a missile impact on window glass. v