Dynamic fluid-structure interaction of graded foam core sandwich plates to underwater blast

The aim of this paper is to address characteristics of cavitation evolution caused by the one-dimensional fluidstructure interaction as the graded foam core sandwich panels are subjected to underwater impulsive loadings. A transparent underwater shock tube is adopted to generate controllable and planar blast impulses exerted on the fully clamped sandwich panels. The effects of the impulsive intensity, core strength, core density gradient, and boundary condition are carried out to examine the cavitation evolution during the dynamic fluid-structure interaction. The results show that the initiation, extension, and collapse of the cavitation are significantly determined by the propagations of the breaking front and the closing front, which have different correlations with the considering effects. Due to the dynamic core compression and unloading, the distinct elevating speed of the closing front is firstly found in the fluid-structure interaction under the impulsive loadings. During the cavitation evolution, the non-uniformed distribution of the cavitated bubbles indicates that the cavitation region closer to the fluid-solid interface experiences more considerable pressure drops. The dynamic response of the weakest layer of the core shows predominant influences on the propagation trajectories of wave fronts and reducing of the cavitation ratio, indicating that the core gradient design can efficiently decrease the transmitted impulse and has superiority to the uniform cores with the identical areal mass.