Effects of reinforcement geometry on the elastic and plastic behaviour of metal matrix composites

The mechanical properties of an AlSiC composite system are modelled using the Boundary Element Method. A unit cell approach, in three dimensions, is used to model the composites. The metal matrix is allowed to deform plastically, while the ceramic reinforcement is assumed to remain perfectly elastic. Several types of reinforcement are modelled, at various volume fractions, and with different degrees of clustering. The effects of thermal residual stresses, resulting from thermal processing, are also modelled. It is found that, even at relatively low volume fractions, the shape and orientation of the reinforcement phase has significant effects, both in the elastic and plastic domains. Orientation of the reinforcement is particularly critical if the aspect ratio of the reinforcement is high. The stress field within the reinforcement particle is also analysed.