Experimental investigation on distance effects in repeated low velocity impact on fiber–metal laminates

Repeated low velocity impact tests were performed on Glare 5 using a drop impact tower. The effect of impact location distance on plate response, damage parameters and absorbed energy were studied. The damage evolution was evaluated using visual inspection, ultrasonic C-scan, SEM and mechanical sectioning techniques. Plastic deformation, strain hardening and perforation were observed with increasing number of impacts. The role of the metal in repeated impacts is important and becomes evident considering the distance between impact locations. Prior to the appearance of cracks, a decrease in the impact location distance results in an increase of plate stiffness. However, in presence of cracks, the decrease of impact distance results in a decrease of plate stiffness.