Computer simulation of residual stress distribution and microcracking due to thermal expansion anisotropy

Spontaneous microcracking during cooling is observed in myriad polycrystalline ceramic materials. This phenomenon is attributed to residual stresses that develop in the microstructure due to thermal expansion anisotropy, thermal expansion mismatch, and/or phase transformations. In this study, the residual stress distribution due to thermal expansion anisotropy is analysed. Microcracking in realistic microstructures is investigated using a microstructural finite element model. Microcrack formation and propagation are modelled via a local Griffith-type failure criterion. Influences of grain size distribution and microstructural randomness on the initiation threshold as well as on the damage accumulation are analysed. Emphasis is on the latter. Results are presented for microcracking in simulated alumina.