EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The applicability of the well-known Irwin’s estimate to metals containing particles becomes dubious when the size of the plastic zone (PZ) is comparable to the particle spacing. In this work, a 3D multiscale model is used to investigate the crack tip plasticity in a cyclically loaded elastic-perfectly plastic matrix containing a realistic distribution of spherical particles. Homogenization and dimensional analysis are used to show that the shape of the cyclic PZ differs from what expected based on standard von-Mises plasticity. Due to its irregular shape, it is suggested to characterize the PZ in terms of the square root of the plastic area. The scaling of the cyclic PZ size with the square of the stress intensity factor is confirmed, but the proportionality factor is strongly affected by the particle volume fraction. Consequently, a new formula to estimate the size of the cyclic PZ is proposed. A thorough sensitivity analysis demonstrates that the formula is applicable over a wide range of material properties, spanning from Al-matrix composites to nodular cast irons, and it is robust to minor particle deviations from the spherical shape.