Modeling fracture in aluminium based metal matrix composites using a statistical approach

Fracture in an A16061 based metal matrix composite (MMC) containing 20 vol.% Al2O3 particles is modelled using an axisymmetrical finite element model and a statistical approach for calculating strengths of ceramic via Weibull's model. In this model, the MMC is assumed to fail as soon as the particle has failed. By plotting the calculated survival probability of an Al2O3 particle versus the macroscopic axial stress applied on the whole MMC, the applicability of Weibull statistics on these type of new materials can be checked. It can be concluded that for higher triaxialities, the Al2O3 particle fails before plasticity in the matrix occurs. Furthermore, knowing the stress distribution in a ceramic particle, Weibull's model can be used to calculate the survival probability of ceramic particles in ductile matrices, however, the Weibull modulus becomes meaningless when a non-proportional stress distribution in the matrix occurs.