Development of a micro-indentation model simulating different mechanical responses of the fibre/matrix interface

An analytical shear-lag model has been developed for quantifying the interfacial shear strength of glass-reinforced composites from micro-indentation experiments. The model takes into account the local fibre environment, together with the occurrence of debonding and fibre sliding. In order to simulate the experimental indentation curves, various interfacial laws have been implemented. In a first approach, it was assumed that the shear stress in the debonded part of the interface was constant and proportional to the debonding stress. A more refined generalised interface law relating the shear stress to the fibre displacement was subsequently introduced to describe a progressive transition from an adhesive to a sliding state. The model has been successfully applied to the analysis of experimental reduced indentation curves giving the displacement of the fibre surface as a function of the applied load.