Numerical modelling of particle distribution effects on fatigue in Al–SiCp composites

Various reports in the literature have highlighted the effects of particle distribution on the fatigue behaviour of particulate reinforced metal matrix composites (PMMCs), although few attempts have been made at modelling such effects. A micromechanical understanding of the effects of clustering on short crack growth behaviour in Al–SiCp composites has been achieved via finite element modelling. Comparison of preliminary models with the literature has shown that shielding/anti-shielding effects were significantly affected by the relative sizes of the particle and the overall model such that, when edge effects were removed, a crack was predicted to be accelerated rather than decelerated as it propagated through closely spaced pairs of particles. Consistent differences were identified between models with homogeneous versus clustered particle arrangements in terms of crack path morphologies and local crack–tip stress intensity fluctuations. Furthermore, predicted influences of clustering on growth rates in the numerical models were found to be consistent with previous experimental results (i.e. growth rates rose with increased clustering), demonstrating that load transfer effects associated with changes in particle distribution may play a direct role in controlling the growth of short cracks in these materials.