Amorçage et propagation de fissures dans les milieux ductiles non locaux

Abstract : Within the framework of industrial structures design, a novel methodology is presented which allows to model ductile damage evolution followed by crack initiation and propagation. This study is divided into three parts. First, damage evolution should be properly described with a continuous model up to the onset of fracture. However, solving finite element problems involving elasto-plasticity coupled with damage softening faces two major difficulties: mesh dependence and volumetric locking. In this work, a four-field mixed nonlocal formulation is proposed in order to solve simultaneously both problems within the small strain framework. Then, accuracy is improved and computational costs are minimized thanks to a mesh adaptivity procedure based on an error indicator. The strategy combines a direct transfer of the smoothed fields at the old Gauss points to the new ones with a viscous model, so that computation can continue on the adapted mesh after reducing the time step. Finally, once the first stage of damage evolution is described accurately, a new strategy using remeshing techniques is proposed for crack initiation and propagation. The crack path is represented by an auxiliary mesh with a regular crack tip. The discontinuity is oriented according to a criterion depending on the gradient of the smoothed damage field. A numerical application is presented on a double notched specimen both in 2D and in 3D. Future work should focus on applying this methodology to more realistic models involving stress triaxiality within the finite strain framework.
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Submitted on : Monday, April 4, 2011 - 3:26:43 PM
Last modification on : Monday, November 12, 2018 - 11:01:33 AM
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  • HAL Id : pastel-00583011, version 1

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Sylvia Feld-Payet. Amorçage et propagation de fissures dans les milieux ductiles non locaux. Matériaux. École Nationale Supérieure des Mines de Paris, 2010. Français. ⟨NNT : 2010ENMP0035⟩. ⟨pastel-00583011⟩

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