Crack initiation strength of an interface between a submicron-thick film and a substrate

The focus of this study was to evaluate the fracture initiation criteria of the interface between a thin film and a substrate by Bogy’s, Kitamura’s and Griffth’s methods. The critical stress intensity parameter KijC in Bogy’s method and the concentrated stress parameter σijC in Kitamura’s method were calculated based on the singular stress field near the interface edge. The work of separation per unit area Γο in Griffth’s method was calculated based on the work of fracture process. The results obtained show that in comparison among interface strengths, the fracture toughness KθθC and the concentrated stress parameter σθθC were respectively applied to material combinations with specific edge geometry and with weak stress singularity, while the work of separation per unit area Γο was applied in all cases.