Numerical Investigation of Asymmetric Strain Controlled Fatigue Behaviour Using Kinetic Theory of Fracture and Peridynamics

Abstract

Abstract Numerical fatigue process modelling is complex and still open task. Discontinuity caused by the fatigue crack requires special finite element techniques based on additional parameters, which selection has a strong effect on simulation results. Moreover, fatigue life calculation according to empirical material coefficients (e. g., Paris law) does not explain the process and coefficients should be set from experimental testing, which is not always possible. New non-local continuum mechanics formulation without spatial derivatives of coordinates – peridynamics (PD), created 20 years ago, brings new opportunities modelling discontinuities, such as fatigue crack. The fatigue process can be better described by using the atomistic approach based kinetic theory of fracture (KTF), which includes the process temperature, maximum and minimum stress, and the loading frequency in its differential fatigue damage equation. Standard 316L stainless steel specimens are tested, and then the KTF-PD fatigue simulation is run in this study. The in-house MATLAB code, calibrated from the material S-N curve, is used for the KTF-PD simulation. A novel KTF equation based on the cycle stress-strain hysteresis loop is proposed and applied to predict the fatigue life. The simulation results are compared with the experimental results, and good agreement is observed for both symmetric and asymmetric cyclic loading.