Computational simulations of thermal shock cracking by the virtual crack closure technique in a functionally graded plate

Thermal cracking in a ceramic/metal functionally graded plate under thermal shock loading, when the plate is cooled from high-temperature to ambient low one, is numerically analyzed with the commercial finite element software ABAQUS™. Continuous position-dependent functions were created for the mechanical and thermal coefficients of FGM and, then, implemented as user-defined material properties via respective subroutines of the ABAQUS code. In order to find a temperature field and associated thermal stresses in the FGM plate, a linear quasi-static thermoelastic problem for a plane strain state is solved. The distributions of temperature and thermal induced stresses accounting for residual stresses inside the plate are calculated under conditions of both the steady state and transient thermal processes. The solution of the transient heat conduction problem is used for crack propagation simulation using the virtual crack closure technique. The crack lengths developed on the ceramic surface during the thermal shock for different graduation profiles are computed. It is shown that the crack lengths are influenced by the material gradient profile of the functionally graded plate. Hence, the conclusions on the crack resistance of FGM plates are drawn.