In this work we extend the well-posedness for infinitesimal dislocation-based gradient
viscoplasticity with linear kinematic hardening from the subdifferential case to general
nonassociative monotone plastic flows. We assume an additive split of the displacement
gradient into nonsymmetric elastic distortion and nonsymmetric plastic distortion. The
thermodynamic potential is augmented with a term taking the dislocation density tensor
into
account. The constitutive equations in the models we study are assumed to be only of
monotone type. Based on the generalized version of Korn’s inequality for
incompatible tensor fields (the nonsymmetric plastic distortion) due to Neff et al. the
existence of solutions of quasistatic initial-boundary value problems under
consideration is shown using a time-discretization technique and a monotone operator
method.