Elastic-plastic stress transfer in short fibre-reinforced metal-matrix composites

The classical shear lag model was modified to study the elastic-plastic stress transfer in short fibre-reinforced metal-matrix composites. The effect of the matrix plastic deformation on the stress transfer in the elastic range was analysed by introducing a plastic strain. The stress transfer in the overall plastic range was analysed by using the incremental form of the stress and strain relation. The expressions for the fibre stress and the interfacial shear stress in a cylindrical unit cell including the fibre end region were derived with the use of the technique of adding imaginary fibre. The modified model was then used to study the effects of thermal residual stresses on the tensile and compressive stress-strain responses of the composite. It was demonstrated that the stress transfer efficiency in the elastic range is reduced due to the matrix local plastic deformation. In the presence of thermal residual stresses, different variations of the matrix plastic strain result in asymmetric tensile and compressive stress-strain responses. The model predictions exhibited very good agreements with the experimental results in a SiCw/Al-Li composite.