Influence of SiC particles orientation on fretting crack extension in an Al-SiC metal matrix composite

Abstract

The effect of SiC particle orientation regarding the fretting cracking process of an Al-SiC metal matrix composite (MMC) is investigated. Focusing on the crack extension below a sphere-on-flat fretting contact after 106 loading cycles, it is shown that the maximum crack extension is observed when the SiC particles are collinear with the crack path (i.e. perpendicular to the fretting tensile stress). The minimum extension is by contrast observed when the SiC particles are perpendicular to this latter. The crack extension seems favoured when the crack path follows the interface between the SiC particle and the Al matrix but slows down when the particles are perpendicular to the crack path. The crack must then fracture the reinforcing particle. These various experiments are simulated using a 3D finite element modelling (FEM) including the presence of a 3D crack shape. Considering that the crack arrest condition is reached (i.e. plain fretting cracks do not extend anymore after 106 loading cycles), the crack arrest thresholds ΔKth from short to long crack regimes as a function of the SiC particles orientation are extracted from a reverse analysis of the experiments.