Effect of residual stresses on the propagation of interface cracks between dissimilar brittle materials: Contribution of two and three-dimensional analyses

A methodology is proposed to assess the contribution of residual stresses to the debonding risk in multilayers used as cells for energy conversion at elevated temperature. The conditions of an interface crack extension, given by the Energy Release Rate (ERR) and mode-mixity, are fully investigated for thermal and mechanical loadings. Mode-mixity is calculated from Finite Element Modeling (FEM) thanks to an extension of Matos’ approach to 3D crack geometries. The methodology is applied on the configuration of straight crack propagating all along the width of a bimaterial interface. It is shown that values of ERR given by 2D plane models can be used as bounds of three-dimensional numerical results far from free surfaces. For thermal loading, anti-plane mode and ERR are found to rise near the edge with a magnitude that can not be predicted by 2D analysis. Furthermore, it has been found that thermal stresses tend to shift both the ERR and phase angle values induced by mechanical loading. More particularly, thermal stresses can be detrimental in some configurations since the combination with a mechanical loading strongly increases the crack opening mode.