Metallic sandwich panels subjected to multiple intense shocks

Abstract

Mechanical response and fracture of metal sandwich panels subjected to multiple impulsive pressure loads (shocks) were investigated for panels with honeycomb and folded plate core constructions. The structural performance of these panels to multiple impulsive pressure loads is quantified by the maximum transverse deflection of the face sheets and the core crushing strain at mid-span of the panels. A set of simulations was carried out to find the near-optimum core density of a square honeycomb core sandwich panels. The panels with a relative core density of 4-5% are shown to have minimum face sheet deflection under multiple shock loading, which was consistent with the findings related to the sandwich panel response subjected to a single intense shock. Comparison of these results showed that near-optimized sandwich panels outperform solid plates under shock loading. An empirical relationship for obtaining the effective peak over-pressure were derived which allows prediction of the deflection and fracture sandwich panels under two consecutive shocks. Moreover, limited number of simulations related to response and fracture of sandwich panels under multiple shocks with different material properties were performed to highlight the role of metal strength and ductility. In this set of simulations, square honeycomb sandwich panels made of four steels representing a relatively wide range of strength, strain hardening and ductility were studied. For panels clamped at their edge, the observed failure mechanisms are core failure, top face failure and tearing at or close to the clamped edge. Failure diagrams for sandwich panels were constructed which reveal the fracture and failure mechanisms under various shock intensities for panels subjected to up to three consecutive shocks. The results complements previous studies on the behavior and fracture of sandwich panels under high intensity dynamic loading and further highlights the potential of these panels for development of threat-resistant structural systems.