Application of Different High-Order Boundary Conditions to Crystal Plasticity

Abstract

When Burgers vector is accounted for in crystal plasticity theories through energetic dependences, high-order boundary conditions are required. In the work done by Gurtin and Needleman (J. Mech. Phys. Solids, 53:1-31 (2005)) is shown that a boundary condition based directly on slip-rates is inappropriate for being too restrictive. The authors suggest a new type of boundary condition based on the flow of the Burgers vector. In the present work, the two types of boundary conditions are implemented in a finite element crystal plasticity code. Only small-deformation and 2D cases are considered. Details about the new formulation are commented. The boundary conditions are tested considering a single crystal and hard surfaces. Preliminary results show that the use of the second type of high-order boundary condition leads to more adequate results than the first type, when compared to discrete dislocation results.