Interface cracks in layered materials subjected to a uniform temperature change

Elastic and incremental elasto-plastic analyses have been used to evaluate the driving force for interface edge-crack growth initiation in tri-layered material systems subjected to a monotonic variation in temperature. Whenev er possible, closed-form solutions are derived as functions of the thermo-m echanical material properties and the geometry of the layers. Analytical ex pressions for the different critical temperatures at which distinct transit ions occur in thermally induced deformation are presented and are correlate d with the three regimes of interface fracture; elastic, partially plastic and fully plastic. Furthermore, a large-scale contact model, which predicts the shielding effect of contact in the wake of an interface crack, is also presented and the attendant reduction in the energy release rate is estima ted. Finite element results, showing the influence of layer geometry and st rain hardening on the energy release rate, are presented for a model Al2O3/ Ni(Cr)/Al2O3 tri-layered system; these simulations confirm the bounds predi cted by the theory.