Microdamage modelling of crack initiation and propagation in FCC single crystals under complex loading conditions

A regularised anisotropic continuum damage mechanics model is presented that couples crystal plasticity with damage induced on crystallographic planes. Two and three-dimensional finite element simulations of crack initiation and propagation in single crystal specimens under complex multiaxial loading with dominating shear are presented for the first time. The crack path in a four-point double notched shear specimen is predicted, in accordance with experimental testing of single crystal nickel-based superalloy AM1. The initiation, bifurcation and propagation of a crack in a shifted double notched specimen under creep conditions is then simulated and compared to the experimental response of nickel-based superalloy MC2 at high temperature. The attention is focused on the influence of coupling between viscoplasticity and damage on the crack path in these single crystals.