Simulation of Directional Distribution of Slip-Band Crack under Biaxial Low Cycle Fatigue

摘要

The growth of dominant crack is sometimes affected by distributed small cracks in multiaxial low cycle fatigue. Considering such a situation, crack initiation in biaxial fatigue was first modeled in this work. In modeled grains, normal directions of slip planes and slip directions on respective planes were independently given at random. A slip-band crack was presumed to be initiated along the given slip direction on the specified slip plane when the resolved shear stress in the slip direction exceeded a critical shear stress. The crack initiation life was also evaluated using a dislocation pile-up model. Simulations on crack initiation were conducted under the same loading conditions as experiments. Simulated directional distribution of initiated cracks was compared with experimental results obtained in biaxial fatigue tests using tubular specimens of pure copper, and it showed a good agreement with the experimental observation.