Visco-plastic constitutive model considering non-proportional hardening at elevated temperature under multiaxial loading

Based on the Chaboche unified visco-plastic constitutive model, a visco-plastic constitutive model which can take into account non-proportional hardening was proposed for nickel-base alloy at elevated temperature under multiaxial loading. In the proposed multiaxial visco-plastic constitutive model, the non-proportional hardening is considered as a change of kinematic hardening property. The kinematic hardening parameters which can evolve exponentially with the cumulative plastic strain and rotation factor resulted from loading path were proposed to take into account the non-proportional hardening at high temperature under non-proportional loading. Experimental verification showed that the proposed model can accurately predict the peak stresses and the hysteresis loop compared with the original model during the tension-torsion loading process for nickel-base alloy at elevated temperature under non-proportional loading.