Propagation of interface edge cracks by mechanical and thermal strains

Abstract

Computer simulations of decohesion along one of the interfaces between a thin ductile metal layer and elastic substrates are carried out by using a finite element method. The layer is taken to be elastic-plastic and the fracture process zone has separation characteristics that follow a traction-separation law. This law is characterized by the peak separation stress σ and work of separation per unit area Γ0. The effects of thermal loading rate, the layer thickness and layer-substrate modulus mismatch on the steady-state interface toughness, plastic zone size and shape are investigated. Our simulation results show that the heating process is more critical than the cooling process. Both thin film thickness and elastic mismatch between the film and substrates have marked effects on the steady-state toughness.