Prediction of the mechanical behaviour of short fiber reinforced MMCs by combined cell models

The flow behaviour for metal matrix composites reinforced with 2D (planar) and 3D randomly oriented short Al2O3 fibers is investigated by combined cell models in conjunction with the finite element method. The mechanical behaviour of short fiber reinforced metal matrix composites (MMCs) with a given fiber orientation can be simulated numerically by averaging results derived from different cell models. These cell models involve two 2D models and two 3D models representing a single fiber in three principal orthogonal planes in the composite. Stress-strain curves have been calculated for MMCs reinforced with 2D randomly planar and 3D randomly oriented short fibers by an appropriate integration of results of all fiber orientations. The numerical results are compared with experimental data of a fiber reinforced aluminium alloy composite obtained in uniaxial tension and compression tests. Good agreement is obtained between experimental results and the predictions of the model in the regimes where no microdamage is observed experimentally, Finally, the effects of residual stresses have been estimated using the model. Both, in tension and in compression, Young's modulus is found to be lower while the yield stresses are increased compared to the case when residual stresses are absent. (C) 1997 Elsevier Science B.V.