Delamination of a strong film from a ductile substrate during indentation unloading

摘要

In this work, a finite element method was performed to simulate the spherical indentation of a ductile substrate coated by a strong thin film. Our objective was to study indentation-induced delamination of the film from the substrate. The film was assumed to be linear elastic, the substrate was elastic-perfectly plastic, and the indenter was rigid. The interface was modeled by means of a cohesive surface. The constitutive law of the cohesive surface included a coupled description of normal and tagential failure. Cracking of the coating itself was not included. During loading, it was found that delamination occurs in a tangential mode rather than a normal one and was initiated at two to three times the contact radius.