Dynamic Responses of Aluminum Foam Sandwich Shells under Repeated Impact Loadings

The deformation and energy dissipation mechanism of the aluminum foam sandwich shell under repeated impact loads were investigated by numerical simulation. The effects of radius of curvature, thicknesses distribution of the front/back face sheets, core thickness and impact energy gradient on the repeated impact resistance and energy absorption capacity of the structure were analyzed. It is shown that the deformation of the aluminum foam sandwich shell structure accumulates under repeated impact loads, with local bending deformation of the front face sheet, local compression of the foam core, and global bending deformation of the back face sheet. As impact times increases, the peak impact force and integrated bending stiffness increase, and the impact duration and energy absorption capacity decrease. When each impact energy is the same, for aluminum foam sandwich shell structure, the larger the curvature, the higher the energy absorption capacity, while the midpoint deflections of the front and back face sheets after five repeated impacts are larger than that of the shell structure with smaller curvature. Under five repeated impact loads, when the thickness of the front face is large and the back face is small, the specific energy absorption of the structure is lower, but the midpoint deflection of the back face is smaller. The larger the thickness of the aluminum foam core, the smaller the deflection of the back face of the structure, but the total specific energy absorption is reduced. Under the impact energy with three different gradients, the energy absorption of the structure is the highest when the impact energy is increased successively, and the deflections of the front and back faces are larger, while the energy absorption of the structure is the lowest, and the deflection of the front and back faces is smaller when the impact energy is decreased successively.