Modelling impact deformation of foam-plate sandwich systems

Abstract

Foam-plate sandwich systems comprising ten layers of crushable polyurethane foam separated by mild steel plate inserts are subjected to impact deformation at velocities ranging from 3 to 8 m/s using a drop tower. Four geometrical arrangements, namely uniform-width, tapered-width, hourglass and double tapered-width profiles, are studied to identify the effects of varying the distribution of structural compliance and inertia on impact response. The investigations focuses on the force transmitted through the sandwich systems and the development of deformation. A one-dimensional mass-spring chain model is formulated to describe the observations. Both theoretical and experimental results indicate that the systems geometry has a significant influence on the development and distribution of deformation and consequently, the force-time response. The theoretical model provides reasonable predictions of the final damage distribution in each system and good correlation is observed between the theoretical and experimental transmitted force response in terms of overall behaviour. In essence, the study shows how the impact force transmitted by an energy-dissipating system can be controlled by manipulating the distribution of inertia and compliance within the system. © 1997 Elsevier Science Ltd.