A physically based gradient plasticity theory |
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| Institution: | 1. Department of Solid Mechanics, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden;2. SKF Engineering & Research Centre, P.O. Box 2350, 3430 DT Nieuwegein, The Netherlands;1. State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China;2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China;1. Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China;2. Singapore Institute of Manufacturing Technology, Agency for Science, Technology and Research (A*STAR), Singapore;3. PolyU Shenzhen Research Institute, No. 18 Yuexing Road, Nanshan District, Shenzhen, PR China;4. State Key Laboratory of Solidification Processing, School of Materials Science & Engineering, Northwestern Polytechnical University, Xi''an, 710072, PR China;5. State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, 200240, PR China |
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| Abstract: | The intent of this work is to derive a physically motivated mathematical form for the gradient plasticity that can be used to interpret the size effects observed experimentally. The step of translating from the dislocation-based mechanics to a continuum formulation is explored. This paper addresses a possible, yet simple, link between the Taylor’s model of dislocation hardening and the strain gradient plasticity. Evolution equations for the densities of statistically stored dislocations and geometrically necessary dislocations are used to establish this linkage. The dislocation processes of generation, motion, immobilization, recovery, and annihilation are considered in which the geometric obstacles contribute to the storage of statistical dislocations. As a result, a physically sound relation for the material length scale parameter is obtained as a function of the course of plastic deformation, grain size, and a set of macroscopic and microscopic physical parameters. Comparisons are made of this theory with experiments on micro-torsion, micro-bending, and micro-indentation size effects. |
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