Non-proportionally multiaxial ratcheting of cyclic hardening materials at elevated temperatures: Experiments and simulations

The uniaxial and non-proportionally multiaxial ratcheting behaviors of cyclic hardening materials at room and elevated temperatures were studied by experiments first. As an auxiliary experiment to reveal the cyclic hardening/softening feature of the material and determine the material parameters used in the developed model, the material was also tested under a uniaxial and a non-proportionally multiaxial strain cycling. Simultaneously, the effects of different loading conditions at certain temperature on the strain cyclic deformation and ratcheting were analyzed. It is shown by experiments that, the strain cyclic deformation and ratcheting behavior of the material have a great dependence on the ambient temperatures, especially to a specific range of 400-600 °C, i.e., the material exhibits a markedly dynamic stain aging so that a higher cyclic hardening and lower ratcheting are resulted in, as comparing with the results at other temperatures. Then, based on the aforementioned experimental results, the temperature-dependent ratcheting of the material was simulated by constructing a new visco-plastic constitutive model. In the developed model, the Ohno-Abdel-Karim kinematic hardening model [Ohno, N., Abdel-Karim, M., 2000. Uniaxial ratcheting of 316FR steel at room temperature: II. Constitutive modeling and simulation. ASME J. Eng. Mater. Technol. 122 (1), 35-41] was extended to simulate the temperature-dependence of ratcheting behavior reasonably by introducing some temperature-dependent terms. It is shown that the simulated results agree with the corresponding experimental results well.