Fatigue crack propagation trajectories under mixed-mode cyclic loading

As the direction of the mixed-mode fatigue crack growth may not be known in advance, a new methodology is proposed to simulate the fatigue crack trajectories under general in–plane cyclic loading. The accumulated elastic strain energy is calculated in the vicinity of the crack tip for all possible prospective propagation directions. It is assumed that the fatigue crack extension takes place along the prospective direction which results to the minimum accumulated elastic strain energy in the vicinity of the crack tip. A new factor related to the accumulated elastic strain energy within a circular core around the crack tip seems to be a suitable parameter for predicting the mixed-mode fatigue crack growth path, as well as the fatigue crack growth rate. Using the proposed concept to perform the above predictions, only mode-I fatigue test data are required. Theoretical predictions are correlated well with test results taken by the literature.