Curved sandwich composite panels subjected to a near-field underwater explosion

Composite sandwich structures have emerged as promising systems for marine structures. However, these structures are susceptible to underwater shock loading due to their application in marine environments. This work focuses on experimentally investigating the response of curved polymeric composite sandwich structures to near-field underwater explosions (UNDEX). High-speed image acquisition and 3D digital image correlation (DIC) were used to evaluate the panel deflection. Additionally, high-speed cameras captured the dynamics of the explosion bubble and the fluid–structure interaction. The oscillation and migration of the explosion gas bubble were studied for different standoff distances. Additionally, surface cavitation bubbles were examined under varying structural stiffness and loading intensities. Dynamic pressure sensors were positioned to record and characterize the loading generated using a bridge wire detonator. The results indicate a dependence of the dynamics of the surface cavitation bubble on the loading intensity and structural stiffness. Additionally, a greater migration of the explosion bubble towards the structure was observed for shorter standoff distances. Panels with a higher density of foam core exhibited greater strength and stiffness, resulting in lower panel deflections. Furthermore, a higher deformation mode in the sandwich structure was observed due to the curved geometry of the panels.