Prediction of crack propagation direction for holes under quasi-static loading

The simulation of crack propagation relies on accurate computing of stress intensity factors (SIFs) at crack tips. Numerical methods are used to calculate the crack propagation path based on the computation of the crack incremental direction and stress intensity factors KI, KII from the finite element response. This paper evaluates displacement extrapolation technique (DET) for prediction of stress intensity factors. The DET is used when the singular element is present at the crack tip and it uses the differential displacements for the adjacent nodes across the crack to compute the stress intensity factors. The crack path and its stress intensity factors are calculated in a specialized finite element program, using small crack increments. At each crack propagation step, the mesh is automatically redefined based on automatic adaptive strategy that takes into account the estimation of stress analysis in two-dimension. The crack is free to propagates without predetermine path direction. Maximum circumferential stress criterion is used as the direction criterion. Some examples are presented to show the results of the implementation.