Dislocation cell-based continuum crystal plasticity model for the size effect and strain jump plasticity deformation behavior of single crystal micropillar

Experiments have found that the size effect and strain jump during plastic deformation is dependent on the dislocation cells inside. Despite this, continuum crystal plasticity model of micropillar is built with weak connections to dislocation cells mechanisms. This work proposes a new continuum crystal plasticity model by considering the evolution of average size of dislocation cell walls and cell interiors. Additionally, to detect strain jump, second-order work criterion is introduced by considering the evolution of dislocation cell substructure. The proposed approach is implemented in finite element simulations of Ni micropillar specimens (diameter range: 5-20μm). The simulation results demonstrate that the new model successfully captures both the size effect and strain jump phenomena, showing close alignment with experimental measurements. These specific plastic deformation behaviors, particularly the size effect and strain jump stem from variations in both the diameter of micropillars and the mean size of dislocation cell substructure. Moreover, the dislocation cell structure becomes more refined as plastic deformation intensifies.