Quantitative analysis of the micro-indentation behaviour of fibre-reinforced composites: development and validation of an analytical model

A shear-lag model has been developed in order to assess interfacial shear s trength from micro-indentation experiments. The treatment of the experiment al load/displacement curves is based upon the quantification of the two com ponents of the indenter displacement, i.e. (i) the elasto-plastic indentati on of the fibre surface by the Vickers indenter, and (ii) the displacement of the fibre surface due to its compression and to the deflection of the ma trix. The latter component has been modelled by using an analytical shear-l ag model which takes into account both fibre/matrix debonding and fibre sli ding in the debonded areas. Some of the basic hypothesis of this analytical approach have been checked by finite-element (FE) simulations with appropr iate model configurations. By means of this model, the critical shear debon ding stress can be obtained from the experimental indentation curves. Moreo ver, the data-reduction scheme takes into account separately the local envi ronment of each indented fibre. This method has been successfully applied t o experimental data by using a unidirectional E-glass/epoxy composite. (C) 2000 Elsevier Science Ltd. All rights reserved.