Abstract:

Spurious forces are a significant challenge for multi-scale methods, e.g., the coupled atomistic/discrete dislocation (CADD) method. The assumption of isotropic matter in the continuum domain is a critical factor leading to such forces. This study aims to minimize spurious forces, ensuring that atomic dislocations experience more precise forces from the continuum domain. The authors have already implemented this idea using a simplified and unrealistic slipping system. To create a comprehensive and realistic model, this paper considers all possible slip systems in the face center cubic (FCC) lattice structure, and derives the required relationships for the displacement fields. An anisotropic version of the three-dimensional CADD (CADD3D) method is presented, which generates the anisotropic displacement fields for the partial dislocations in all the twelve slip systems of the FCC lattice structure. These displacement fields are tested for the most probable slip systems of aluminum, nickel, and copper with different anisotropic levels. Implementing these anisotropic displacement fields significantly reduces the spurious forces on the slip systems of FCC materials. This improvement is particularly pronounced at greater distances from the interface and in more anisotropic materials. Furthermore, the anisotropic CADD3D method enhances the spurious stress difference between the slip systems, particularly for materials with higher anisotropy.

Key words: multi-scale method, anisotropic coupled atomistic/discrete dislocation (CADD), spurious force, partial dislocation, face center cubic (FCC) material