Shear lag models for discontinuous composites: fibre end stresses and weakinterface layers

A new shear lag (SL) type model for stress transfer in a composite with cyl indrical fibres is derived. It accounts for fibre end stresses in an approx imate yet realistic manner, and leads to a new formula for predicting the Y oung's modulus of the composites. The predictions of this model were found to agree well with data for metal matrix composites (MMCs) with fibres of v arious aspect ratios. The accuracy and relative simplicity of the new model have been exploited in the development of an approximate analytical model for the stress transfer and macroscopic yield stress of a composite that co ntains a weak layer in the matrix adjacent to the reinforcement. With the a id of the latter model, the proof stress of MMCs which contain a precipitat e free zone (PFZ) around the reinforcement, can be studied; experimental da ta obtained for aged 8090 MMCs is consistent with the model predictions. (C ) 1999 Elsevier Science S.A. All rights reserved.