Investigation on the Dynamic Behaviors of Aluminum Foam Sandwich Beams Subjected to Repeated Low-Velocity Impacts

Abstract

Marine structures are frequently subjected to repeated-impact loadings during navigation and operation. The structural damage accumulates, resulting in structural failures and even serious accidents. Experiments were performed using an INSTRON drop tower to investigate the dynamic behaviors of aluminum foam sandwich beams (AFSBs) subjected to repeated impacts; moreover, the mechanism of plastic deformation and damage and the energy absorption characteristics were analyzed. The results showed that as the number of impacts increased, the AFSB experienced progressive failure. The peak impact force, the deflection of the face sheets, and the rebound velocity gradually increased with increasing numbers of impacts, while their increments declined. However, when cracks occurred on the aluminum foam core and face sheets, as the number of impacts increased, the peak force and the rebound velocity decreased, while the amount of deflection in the front and back faces progressively increased. Before the foam core cracked, as the number of impacts increased, the elastic energy increased, while the plastic energy decreased. Once the foam core cracked, the plastic energy increased suddenly. During repeated impacts, the energy absorbed via local indentation in each impact initially increased with the number of impacts, and then decreased before finally becoming constant.