Higher-Order Stress due to Self Energy of Geometrically Necessary Dislocations

Nobutada Ohno; Dai Okumura

doi:10.4028/www.scientific.net/KEM.340-341.173

Paper Titles

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Effects of Stacking Sequence on Notched Strengths of Cross-Ply CFRP Laminates and Analysis Using a Cohesive Zone Model
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A Modified Kinematic-Hardening Viscoplasticity Model for Off-Axis Creep Behavior of Unidirectional CFRPs at High Temperature
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Evaluation of the Interfacial Properties in Polymer Matrix Composite: Experiments and Elasto-Plastic Shear-Lag Analysis
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Higher-Order Stress due to Self Energy of Geometrically Necessary Dislocations
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Forming Limits Prediction of FCC Sheet Metal Adopting Crystal Plasticity
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High Density Bands of GN Dislocations Formed by Multi Body Interaction in Compatible Type Multi Crystal Models
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Dependence of Localized Deformation on Point Defect Development Caused by Intersected Cross Slip among Dislocations
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Crystal Plasticity Analysis of Dislocation Accumulation in ULSI Cells with Consideration of Temperature Dependence of the Lattice Friction Stress for Silicon
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Higher-Order Stress due to Self Energy of Geometrically Necessary Dislocations

Abstract:

The self energy of geometrically necessary dislocations (GNDs) in single crystals is considered to inevitably introduce a higher-order stress as the work conjugate to slip gradient. It is pointed out that this higher-order stress changes stepwise in response to in-plane slip gradient and thus explicitly influences the initial yielding of polycrystals. The self energy of GNDs is then incorporated into the strain gradient plasticity theory of Gurtin (2002). The resulting theory is applied to 2D and 3D model crystal grains of diameter D, leading to a D-1-dependent term with a coefficient determined by grain shape. This size effect term is verified using published experimental data of several polycrystalline metals. It is thus found that the D-1-dependent term is successful for predicting not only the grain size dependence of initial yield stress but also the dislocation cell size dependence of flow stress in the submicron to several micron range of D.