Dynamic behaviour of aluminium alloy plates with surface cracks subjected to repeated impacts

This paper investigates the behaviour of aluminium alloy plates with and without initial cracks under repeated impacts. Three series of impact tests were conducted to study the behaviour of circular plate that do not have any cracks (series B), have surface cracks with varying length (series L), and have cracks varying depths (series D). A hammer was dropped from the same height with a constant initial striking energy 60J for all tests. It was observed that plates with larger cracks carried smaller impact forces and assumed larger deformations. With the increase in impact number, the effects of crack lengths and depths on the dynamic behaviour became much more significant. Predictions using a rigid-plastic theoretical model were compared with these test results. With the stresses determined based on the true strain-stress curve obtained by standard tension test, the refined analytical formula provides better predictions that agree well with the lab tests.