Simulation of polycrystalline ceramics with micro-cracks

The micro FEM model, which was considered in the middle bottom of a four-point bending macro FEM model, was constructed from a SEM micrograph of an Al2O3-10vol%ZrO2 ceramic, in which the crystallographic information was given to each grain randomly. One micro-crack was introduced in the micro FEM model as a basic case to simulate the four-point bending strength. The strength was determined by the average stress in a one-grain size distance from the crack tip. Two types of micro-cracks were introduced in the model as a second micro-crack, and the strength was compared with the basic case. For the case in which the second crack is parallel to the first crack and apart from the first crack in horizontal direction, the strength was increasing with the second crack closer to the first crack. For the case in which the second crack is parallel to the first crack but apart from the first crack in vertical direction, the strength was decreasing with the second crack closer to the first crack.