Numerical simulation of fatigue crack propagation interacting with micro-defects using multiscale XFEM

Abstract The presence of the micro-defects in the vicinity of a macro-crack tip can either amplify or suppress the SIF (stress intensity factor) of the macro-crack, thus influence the macro-crack propagating path and rate. In the present work, we numerically investigated the influence of the micro-defects (micro-crack and micro-void) on the macro-crack propagation, by using the multiscale method in conjugation with XFEM (eXtended finite element method). This kind of multiscale method can efficiently provide solution of accuracy on both scales without any restrictive assumptions as analytical approximation method. A static crack interacting with multiple randomly distributed micro-cracks is modeled to investigate the influence of the macro–micro-crack inter-distance. Two series of cases are considered, i.e. a growing major crack interacting with nearby micro-crack, a growing major crack interacting with nearby micro-void. The inclination angle of the micro-crack and the radius of the micro-void are varied at studying their influence parametrically on the major crack propagating path and rate. The numerical results can help one to evaluate the residual fatigue life and safety design of components.