Computer simulation of crack propagation path in microstructures at different stages of grain growth

A method of simulating crack propagation in single-phase polycrystals and two-phase composites containing dispersoids is proposed. The microstructures for simulation were generated by the Monte Carlo method using a two-dimensional triangular lattice. The criterion for crack path selection is based on the total released energy rate of the system on crack extension. The crack path is determined by selecting the neighboring lattice in front of the crack tip corresponding to the smallest released rate from five possible crack extension scenarios; cracking along the cleavage plane in a matrix grain, a non-cleavage plane in a matrix grain, along a grain boundary, dispersoid, or the interface between a matrix grain and dispersoid. The crack propagation behavior was analyzed by calculating the surface ratio of the transgranular fracture, crack length ratio and effective fracture energy. The crack paths depended significantly on the constitution of the simulated microstructures such as average matrix grain size, distribution of the dispersoids and ratios of the fracture surface formation energies.