Inhomogeneous deformation is induced in polycrystalline materials even when subjected to simple inelastic deformation history. This inhomogeneity, such as surface roughness and strain concentration, has a predominant influence on the damage of materials and finally results in cracking. In this paper, we discuss the surface roughness accumulation from the viewpoints of crystal plasticity and grain boundary sliding. In order to simulate real polycrystalline material, a sophisticated finite element mesh involving the nonlinear joint/contact surface, which is devoted to grain boundary sliding, is generated. Here, each grain is idealized as a single crystal with a random slip system. The simulated results indicate that the strain distribution is strongly affected by the contact surface, and a periodicity in high strain concentration is observed. Experiments are also carried out to measure both the microscopic strain and the surface roughness.
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