Dynamic response and failure of PVC foam core metallic sandwich subjected to underwater impulsive loading

The sandwich structures with metallic facesheets and PVC foam cores subjected to water-based impulsive loads are investigated experimentally. The blast resistance in terms of dynamic deformation, failure modes and associated mechanisms is evaluated in relation to the effect of load intensity, core density and core height under air-backed and water-backed conditions. The plates are subjected to underwater impulsive loads of different intensities with a lab-scaled underwater explosive simulator. 3D digital imaging correlation and postmortem analysis are used to investigate the deformation and failure of individual components, focusing on the effects of loading intensities, structural properties and loaded conditions. The primary failure modes of cores transfer from core crushing and inelastic deformation to cracks and fragmentation with the increasing applied impulse and core density. The distinct trends of deflection shown by front faces and back faces are influenced by the effect of core density significantly. Unlike the air-backed condition, water-backed condition affects the damage and deflection of the sandwich structure in a different way because of the critical intensity of impulsive loads. Quantitative structure-loading-performance relation is carried out to provide guidance for structural design.