Blast resistance of metallic sandwich panels subjected to proximity underwater explosion

• The loading property generated by close-in underwater blast on structure surface is intuitively characterized by peak pressure distribution.
• Secondary pressure wave generated by moving back skin is proposed in the evaluation of its blast resistance.
• Proximity underwater blast tests are firstly performed on sandwich panels consisting of two face-sheets and a honeycomb core.
• Effect key design parameters on blast resistance and failure mechanism of sandwich panels are experimentally studied and analyzed.

A series of close-in underwater blast tests were performed on sandwich panels consisting of two aluminum alloy face-sheets and a honeycomb core to investigate blast resistance of metallic sandwich panels. The blast resistance of sandwich panels was assessed in terms of structural deformation resistance represented by back face-sheet deflection and intensity of the secondary pressure wave, which is determined by the maximum velocity of the back face-sheet. It was found that the secondary pressure wave shows an inverse trend with face-sheet thickness while a positive relationship with core density, which is determined by foil thickness in this study. A failure mode map was adopted to indentify the effect of design parameters on the structural failure mechanism at this blast magnitude. Finally, a comparison of underwater blast resistance between sandwich panels and monolithic plates of equivalent mass was performed. The comparative study provided further experimental evidence for the benefit of sandwich construction in terms of deformation resistance and secondary pressure wave intensity even at high blast magnitude. It was also suggested that the benefit of deformation resistance was amplified with increase in equivalent thickness.