Stress-gradient plasticity

A new model, stress-gradient plasticity, is presented that provides unique mechanistic insight into size-dependent phenomena in plasticity. This dislocation-based model predicts strengthening of materials when a gradient in stress acts over dislocation source–obstacle configurations. The model has a...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2011-09, Vol.108 (38), p.15716-15720
Main Authors: Chakravarthy, Srinath S, Curtin, W. A
Format: Article
Language:English
Subjects:
Algorithms
Bending
Computer Simulation
Continuum modeling
Deformation
Elasticity
Grain size
Materials
Materials Testing - methods
metals
Modeling
Models, Theoretical
Physical Phenomena
Physical properties
Physical Sciences
Plasticity
Plastics
Polycrystals
Reproducibility of Results
Shear stress
spatial distribution
Stress, Mechanical
Tensile stress
Viscosity
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Description
Summary:A new model, stress-gradient plasticity, is presented that provides unique mechanistic insight into size-dependent phenomena in plasticity. This dislocation-based model predicts strengthening of materials when a gradient in stress acts over dislocation source–obstacle configurations. The model has a physical length scale, the spacing of dislocation obstacles, and is validated by several levels of discrete-dislocation simulations. When incorporated into a continuum viscoplastic model, predictions for bending and torsion in polycrystalline metals show excellent agreement with experiments in the initial strengthening and subsequent hardening as a function of both sample-size dependence and grain size, when the operative obstacle spacing is proportional to the grain size.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1107035108