抄録
This paper describes numerical simulation of boundary crack propagation of Al2O3 ceramics in grain level. A 2D micro FEM model was constructed directly based on the microstructure photographs of a Al2O3 ceramics. In order to link the micro-macro fracture behavior, the micro-model was considered in the middle bottom of a four-point bending macro FEM model. The criterion of micro-crack propagation and the algorithm of crack propagation simulation were discussed. It is assumed that the micro cracking only occurred on the grain boundary, and the mixed-mode fracture was considered to account for complicated boundary fractures. The crack propagation was done step by step and only one grain boundary cracking was occurred for each step. It is shows that the crack initiated from a large grain boundary. The fracture mechanism have consists of three fracture stages of multi-cracking occurring, crack propagation/coalescence, and final instantaneous fracture.
