Microcracking in Ceramics Induced by Thermal Expansion or Elastic Anisotropy

The effect of crystal anisotropy on the formation of grain‐boundary microcracks is analyzed, by considering a planar array of hexagonal grains as a model of a polycrystalline ceramic. The stress singularities at triple‐grain junctions are analyzed by an asymptotic method as well as by a numerical solution, and the critical size of a grain‐boundary defect is investigated by a crack analysis. It is found that elastic anisot‐ropies can significantly increase the stress levels near triple points, which results in a smaller critical grain size for microcracking.

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