Discrete dislocation plasticity analysis of single slip tension

The effect of loading conditions on the tensile stress versus strain response of micron-sized planar crystals with a single active slip system is investigated via finite and small deformation discrete dislocation plasticity analyses. When rotation of the tensile axis is prevented, lattice curvature is induced in the crystal in both the small and finite strain analyses with the build-up of geometrically necessary dislocations resulting in a hardening response. The hardening rate is higher in the small strain analyses and this is attributed to the assumption of linear kinematics in that analysis. On the other hand, when rotation of the tensile axis is permitted, no lattice curvature is induced in the crystal in the small strain analysis resulting in an ideally plastic response. However, the change in the geometry of the crystal induces bending moments in the crystal in the finite strain analyses giving rise to a mildly hardening tensile stress versus strain response.