A Simple Catapult System for Studying the Small Projectile Impact Resistance of Various Glass Laminates

A catapult arrangement capable of propelling small granite chippings at velocities of between 4 and 20 ms^-1 at laminated glass structures similar to those used in car windscreens has been designed and manufactured. The results from a series of studies utilizing this equipment are presented, with the overall aim of reducing the weight of these constructions with no loss in impact resistance. The impact resistance of the laminates has beer, shown to depend strongly on the thickness of the outer glass layer, while the inner glass layer is of secondary, and in most cases, minor relevance. Tests in which the composition and thickness of the interlayer have been varied have revealed that this layer is of no consequence in terms of the impact resistance of the structure as a whole. Chemical strengthening of the outer glass layer has been carried out, and no improvement in performance is observed due to the nature of the stone geometry. Finally, tests on bilayer systems have been carried out, and these results indicate a potential weight saving for no loss in impact performance.