Heterogeneous deformation of polycrystals simulated with micropolar single crystal plasticity

The influence of grain size on the flow stress of small scale statistical volume elements (SVEs) is investigated using micropolar single crystal plasticity. In a micropolar single crystal, the presence of couple stresses work-conjugate to the lattice torsion-curvature leads to a non-symmetric Cauchy stress that when resolved on a given slip system gives rise to kinematic hardening during heterogeneous deformation. The scale-dependent response of the micropolar single crystal is dictated by both energetic (higher-order elastic constants) and dissipative (plastic lattice torsion-curvature) constitutive length scales. In this work, we investigate how variations in these constitutive length scale parameters affect the scaling behavior of the macroscopic (ensemble average) flow stress.