Indentation stress in multi-layer delaminated thin films induced by a microwedge indenter

Indentation stresses in single- and multi-layer delaminated thin films made of elastic–perfectly plastic materials in microwedge indentation delamination tests are analyzed via finite element calculations with different wedge angles and other geometrical and mechanical parameters. Based on the formula for a single-layer thin film under indentation loading [Zhao et al. J Mater Res 2009;24:1943] and by introducing the equivalent material parameters, we developed simple analytical formulae for the loading indentation stress (as well as the energy release rate) in each layer of the multi-layer thin film, in terms of the residual stress, elastic modulus, Poisson’s ratio, yielding strength, and thickness of each layer. Our analytical solution is validated by the finite element calculations and should be useful to thin-film delamination tests.