A large deformation atomistic study examining crystal orientation effects on the stress-strain relationship

We performed large deformation molecular dynamics calculations using the embedded atom method in order to examine yield and plastic flow of single crystal nickel. A parametric study using an analysis of variance technique was used to efficiently determine the influence of the deformation path, temperature, size scale, strain rate, and crystal lattice orientation with respect to yield and the plastic energy. The analysis of variance study revealed that orientation had a primary influence on the volume averaged shear stress, demonstrating the continued importance of slip within the crystal lattice for small sized metals and high applied strain rates. Consequently, other orientations were examined with a focus on averaged shear stress, axial stresses, and stress distributions. Results are presented for crystals oriented for single, double, quadruple, and octal slip, as well as a pseudopolycrystal. One last interesting point is that orientation effects on the stress-strain curves could be only approximately normalized by application of the Schmid factor.