Geomechanics Module New Functionality in Version 5.2a Mixed Isotropic and Kinematic Hardening The plasticity model has been updated so that isotropic and kinematic hardening models can be used simultaneously. Time Derivatives of Plastic Strains Time derivatives of the components of the plastic strain are now available, so it is possible to use expressions like d(solid.epe,TIME) to create strain-rate-dependent plasticity models.