Dynamic response of aluminum corrugated sandwich subjected to underwater impulsive loading: Experiment and numerical modeling

The aluminum sandwich structures with the trapezoidal corrugated core subjected to underwater impulsive loadings are studied experimentally and numerically in the present study. The blast resistance in terms of dynamic deformation, failure modes and associated mechanisms is evaluated in relation to the load intensity, and the core height under air-backed and water-backed conditions. 3D digital imaging correlation and postmortem analysis are employed to investigate the deformation and failure of individual components, focusing on the effects of loading intensities, core height and loaded condition. The discrepancy in bending stiffness along the x-direction and y-direction results in the asymmetrical propagation of plastic hinges and the crack initiates and propagates along the x-direction. Although the core height affects the response rate and the local tendency of deformation greatly as the impulses increase, the core height has a limited influence on the deflection resistance when the corrugated sandwich panels have the same areal mass. The critical impulse for tearing failure of sandwich with higher core height is much smaller than that of panels with lower core height. Due to the resistance and reaction in backwater column, the transverse deflection does not increase monotonously to the increasing core heights and impulses under water-backed condition. The corrugated sandwich panels suffer significantly smaller inner face deflections than the solid plates of identical mass per area under air-backed condition, while all plates involved show approximate blast-resistance performance under water-backed condition.