Constitutive modeling on cyclic stress-strain behaviour of 7A04-T6 high-strength aluminium alloy

In order to improve application of 7A04-T6 high-strength aluminium alloy in structural engineering, 3 monotonic tensile tests and 12 cyclic loading tests were performed, with failure modes, hysteretic stress-strain curves, cyclic backbones and cumulative evolutionary law analysed. It is found that the updated Ramberg-Osgood model was accurately applicable to describe the cyclic backbone of the aluminium alloy. The material constants of two representative cyclic constitutive models, including the Chaboche model and the Giuffre-Menegotto-Pinto model, were calibrated. The rationality of the material constants calibrated were validated through a series of comparisons between experimental and numerical curves. As most test coupons exhibited an ultra-low-cycle fatigue fractured, three popular cumulative damage models, including the Shen & Dong model, Park & Ang model and Kumar & Satish model, were selected and calibrated by using the experimental data. Furthermore, the hysteretic stress-strain curves, evolutionary curves of hysteretic energy and cumulative damage indexes of different structural metals were compared and discussed. The results show that the plasticity-induced cumulative damage of 7A04-T6 high-strength aluminium alloy was generally severer than that of most structural steels. The damage parameter discreteness of the aluminium alloy was also greater than that of structural steels.