Intergranular Strain Evolution near Fatigue Crack Tips in Polycrystalline Metals
Yanfei Gao (University of Tennessee), Peter Liaw ()
Plasticity at Different Length Scales
Mon 9:00 - 10:30
CIT 219
Despite significant advances in material lifetime studies, previous works on fracture and fatigue typically rely on ex situ microstructural characterizations and crack growth monitoring with replica techniques. The in situ, nondestructive, neutron and synchrotron X-ray diffraction techniques, together with the multiscale simulations, will provide us a linkage between the stress analyses (top-down point of view) to the failure mechanisms on inter- and intra-granular scales (bottom-up point of view). A two-scale model is developed to predict the lattice strain evolution near fatigue crack tips in polycrystalline materials. An irreversible, hysteretic cohesive interface model is developed to simulate a steady fatigue crack, which allows us to generate the stress/strain distribution and history near the fatigue crack tip. The continuum deformation history is used as inputs for the micromechanical analysis of lattice strain evolution using the slip-based crystal plasticity model, thus making a mechanistic connection between macro- and micro-strains. By considering the intergranular damage, which leads to vanishing intergranular strains as damage proceeds, we find an excellent agreement between predicted and measured lattice strains in the entire field.