Projectile impact—A major cause for fracture of flat glass

Abstract

Impact is the largest single cause of the fracture of glass objects, although thermal stresses and simple overloading, including pressure loading, also contribute to glass failures. Impact fractures of glass may be caused by either the glass object contacting a hard surface, such as when champagne glasses are thrown into a stone fireplace, or by a projectile striking the glass, such as a baseball encountering a window or a stone striking an auto windshield. In every instance, the impact fracture of glass appears to occur instantaneously, accompanied by an acoustic outburst of discernible magnitude. For these reasons, many glass impact fractures, particularly those of beverage containers, are attributed erroneously to explosions.