Microstructure-based damage and fracture modelling of alumina coatings

Effect of microstructure on damage and fracture evolution due to elastic anisotropy in alumina coatings and a mismatch in thermal expansion of the coating and substrate are examined by means of numerical simulations. Random microstructures of alumina coatings with different porosity levels are generated by the Monte Carlo method based on the Poisson distribution of the number of microdefects (voids/cracks) and their stereological size-shape distributions in plasma-sprayed ceramic coatings. The damage evolution law extended to complex stress states is applied to damage analysis. Failure mechanisms for coatings under uniform thermal loading are investigated with an explicit account for various microstructures.