Measuring interface parameters and toughness—a computational study Original Research Article

Interface toughness of a ductile thin film sandwiched between substrates, Γss, can be evaluated from test data which exhibit steady crack growth characteristics. Γss is the sum of the adhesion energy of the interface Γ0 and the plastic dissipation in the film and substrates Γp. A proper characterization of the quality of interface adhesion requires knowledge of two quantities: the adhesion energy Γ0 and the adhesion strength σ̂. In the present investigation based on a four-point bend geometry, the interface between the ductile film and the substrate is modelled by an adhesion law described in terms of Γ0 and σ̂. The effects on interface toughness of σ̂, of Γ0, and of the geometry and material properties of the layers are studied using a computational model of the test geometry. Through fitting model predictions against test data, a method of evaluating Γ0 and σ̂ is suggested.