The finite deformation theory of Taylor-based nonlocal plasticity

Recent experiments have shown that metallic materials display significant size effect at the micron and sub-micron scales. This has motivated the development of strain gradient plasticity theories, which usually involve extra boundary conditions and possibly higher-order governing equations. We propose a finite deformation theory of nonlocal plasticity based on the Taylor dislocation model. The theory falls into Rice's theoretical framework of internal variables [J Mech Phys Solids 19 (1971) 433], and it does not require any extra boundary conditions. We apply the theory to study the micro-indentation hardness experiments, and it agrees very well with the experimental data over a wide range of indentation depth.