Failure onset in laminated glass units subjected to low velocity missile impact

Abstract

Failure onset occurs usually at the impact site on the exposed surface of the outer glass ply due to large compressive stresses there. In this paper, the probability of this type of damage in five-layer laminated glass units subjected to low velocity small missile impacts is investigated. A dynamic, nonlinear finite element analysis is applied to compute the stress response on impacts. Based on the cumulative damage theory, a damage factor is introduced and related to Weibull's distribution of probability to characterize the probability of damage at the impact site. Analytical results indicate that the probability of damage in the outer glass ply depends strongly on impact velocity, slightly on glass ply thickness, and only very little on interlayer thickness. By comparing the predicted results of five-layer laminated glass units with those of three-layer laminated glass units of the same overall thickness, it is found that five-layer laminated glass units offer a slightly better impact resistance in the outer glass ply.