Crack growth simulation in heterogeneous material by S-FEM and comparison with experiments

A fully automatic fatigue crack growth simulation system is developed using S-version FEM. This system is extended to fractures in heterogeneous materials. In a heterogeneous material, the crack tip stress field becomes mixed-mode (the crack growth path is affected by inhomogeneous materials and mixed-mode conditions). The stress intensity factors in a mixed-mode condition are evaluated using the virtual crack closure method. The criteria for the crack growth amount and crack growth path are based on these stress intensity factors, and the crack growth configurations are obtained. Three crack growth problems are simulated. One is crack growth in a bi-material made of CFRP plate and aluminum alloy. The crack growth paths are compared with the experimental results. The second problem is crack growth in a bi-material made of PMMA and aluminum alloy. By changing the loading condition, several cases are simulated and compared with the experimental results. In the experiment, the crack grows into and along the phase boundary. The effect of the phase boundary is discussed. The last case is crack growth along interface of CFRP plate.