Experimental investigation on the dynamic behaviour of aluminum foam sandwich plate under repeated impacts

Engineering structures in marine and vehicle are frequently subjected to repeated impact loadings. The damage can't be neglected during the accumulation of deflection caused by the repeated impacts. In this paper, the dynamic behaviour of aluminum foam sandwich plate (AFSP) under repeated impacts was investigated by impact tests using INSTRON 9350 Drop Tower. The penetration behavior of front face and back face are compared. Meanwhile, the relationships between deflections of face sheets with impact number as well as the loading-unloading process during repeated impacts are analyzed. Results showed that, the permanent deflections of the front face and back face increased gradually, while the increments decreased until the crack occurred on the front face sheet. The damage modes of front face and back face were different. The impact number (Np) for penetration of front fact and residual number (Nr) for perforation of back face both decreased in exponential form with the increase of impact energy. It implied that the back face sheet still has residual load-carrying capacity even if the front face sheet became cracked.