Investigation of low cycle fatigue crack propagation behavior of 316H steel at 550celcius based on cyclic response and damage accumulation: experiment and modelling

In the framework of the unified elastic-plastic constitutive theory, the cyclic response and damage evolution of 316H steel in the low cycle fatigue (LCF) regime was analyzed and modeled. A unified damage-coupled elastic-plastic constitutive model was established based on the results of uniaxial strain-controlled LCF tests, which includes a novel strain-based continuum damage model in the framework of the critical plane theory, an accumulative plastic strain and fatigue damage-related kinematic hardening model, and an isotropic hardening model. The comparison between the simulated and the experimental results indicated that the proposed model is efficient to precisely characterize the cyclic response throughout the whole fatigue process. The model was also used to simulate the fatigue crack growth behavior under different maximum loads and load ratios via finite element (FE) simulation. The effects of the load conditions on the crack growth rate and crack tip parameters were analyzed systematically.