Basic features of plastic strains: From micro-mechanics to incrementally nonlinear models |
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Authors: | Franç ois Nicot,Fé lix Darve |
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Affiliation: | 1. RNVO Research Group (“Natural Hazards and Structure Vulnerability”), Cemagref, Unité de Recherche Erosion Torrentielle Neige et Avalanches, Grenoble, France;2. RNVO Research Group (“Natural Hazards and Structure Vulnerability”), Laboratoire Sols Solides Structures, UJF-INPG-CNRS, Grenoble, France |
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Abstract: | Most rate-independent constitutive relations for granular materials are based on the existence of a regular flow rule. This assumption states that once the mechanical state of a material point belongs to the yield surface, then the direction of the plastic strains is independent of the loading direction. In this paper, the notion of a regular flow rule is shown to exist only for two-dimensional and axisymmetric loading conditions. By considering our incrementally nonlinear constitutive model, it is established that this notion disappears as soon as more general loading conditions are applied, as also predicted from discrete element simulations. Moreover, a sound micro-mechanical interpretation of the vanishing of a regular flow rule in three-dimensional loading conditions is given from a multi-scale perspective using the micro-directional model. This model highlights the great influence of the loading history on the shape of the plastic Gudehus response-envelope. |
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Keywords: | Elastoplasticity Granular material Discrete element method Micro-mechanics Multi-scale modeling Incremental nonlinearity Flow rule |
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