Effect of loading history on stress-strain relationship of expanding ring Guo Zhaoliang, Fan Cheng, Liu Mingtao, Tang Tiegang, Liu Cangli

Electromagnetic driving expanding ring experiment and explosive expanding ring experiment are two important means for obtaining dynamic tensile mechanical properties of materials. In this study, they were carried out to investigate the dynamic behaviors of oxygen-free copper (TU1) expanding rings. The results show that, during the loading stage, samples driven by electromagnetic force satisfy the assumption of the uniform deformation due to the body force whereas it is not the case with the explosive expanding ring because the sample is impacted by the surface force. With respect to this difference, a new method considering the deformation inhomogeneity was established, where the axial plastic strain and radial plastic strain during impact stage was included in the calculation of the equivalent plastic strain. Through the revised method a more accurate stress-strain relationship of TU1 was obtained.