Quantitative investigations on dislocation based discrete-continuous model of crystal plasticity at submicron scale

• Some key issues in discrete-continuous model (DCM) are investigated.
• A new regularization method is proposed with slip plane dependent regularization parameter.
• Image force can be calculated accurately in the hybrid DCM with stress interpolation.
• The improved DCM can capture slip system rotation and localized deformation.
• Dislocation behavior and stress field in heteroepitaxial films is studied by improved DCM.

Although the multi-scale discrete-continuous model (DCM) which couples discrete dislocation dynamics (DDD) and finite element method (FEM) to study crystal plasticity at submicron scale has been proposed for many years, some key issues are still not well addressed yet. First, a new regularization method with slip plane dependent regularization parameter is proposed in this paper to localize the discrete plastic strain to continuum material points and shows excellent accuracy compared with previous studies. Second, it is often thought of that DCM cannot accurately calculate the so called ‘image force’ acting on the dislocation near free surface. This study argues that the image force can be calculated accurately in the hybrid DCM in which the interpolated stress is used in the computation. The reproduction of deformed crystal configuration during finite deformation is another critical issue in DCM, especially for considering the rotation of slip system. The deformation field transfer between DDD and FEM, and the corresponding treatment of surface dislocations and slip system rotation are proposed to well capture the localized deformation. As an application, the dislocation behavior and stress field in heteroepitaxial films with thin/thick substrates are successfully investigated by the improved DCM.