Thermally induced failure of multilayer ceramic structures

Abstract

In this work, a methodology is proposed to predict the fracture behaviour of multilayer ceramic systems subjected to thermal shock conditions. The statistical variability exhibited by the fracture behaviour of three-layer structures used in solid oxide fuel cells under transient thermal stresses is determined. The dominant fracture mode was found to be unstable crack propagation from existing interfacial defects oriented normal to the plane of the layers. Finite-element analyses and a weight function method are relied upon to obtain analytical solutions for the interfacial crack driving force in two- and three-layer ceramic structures subjected to inhomogeneous in-plane temperature distributions. Failure diagrams are constructed in terms of geometric and loading variables which allow fail-safe regions to be identified. The effect of the elastic property mismatch between the ceramic layers on the maximum interfacial crack driving force is also discussed.