Ref HAL: hal-01717106_v1
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The Saladyn software toolbox is the main outcome of the ANR project Saladyn (COSINUS ANR-08-COSI-014-01), which aims at designing and implementing a new software platform by coupling several kinds of mechanical models and modeling approaches in a single framework : a) solid bodies (deformable), mainly through their finite element representation, b) rigid multi-body systems and c) multi-contact systems. The goal is to obtain a close coupling of these models for the modeling and the simulation in a nonsmooth dynamical framework, able to deal rigorously with the unilateral contact and Coulomb's friction. This platform is composed of the integration of the following components: SALOMÉ, an open-source platform for the pre and post-processing and the coupling of numerical software codes, CODE_ASTER an open-source Finite Element Application, which has already been integrated in Salomé, under the name of Salomé-méca, LMGC90 an open-source software for the modeling and the simulation of multi-contact systems and SICONOS an open-source software for the modeling, the simulation and the control of nonsmooth dynamical systems. In this article, the common formalism and numerical methods are delineated. Several general coupling schemes are described and the interest of the approach is illustrated on several industrial realistic examples.

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Ref HAL: hal-01717105_v1
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Un modèle numérique est développé pour l'analyse d'un écoulement multiphasique dans une formation géologique profonde poreuse, déformable et progressivement endommagée par l'injection de CO2. L'écoulement multiphasique dans le milieu, et à travers les fissures, est décrit par une loi de Darcy généralisée. Les équations gouvernant le couplage avec le squelette solide, incluant les fissures, sont exprimées dans le cadre de la théorie généralisée de Biot. L'implémentation numérique repose sur la méthode des éléments finis pour discrétiser la forme faible des équations gouvernantes, et sur l'adaptation d'un modèle d'érosion de maillage pour simuler l'apparition de fissures.

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Ref HAL: hal-00835121_v1
DOI: 10.1103/PhysRevE.87.062203
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51 citations
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We present a systematic numerical investigation of the shear strength and structure of granular packings composed of irregular polyhedral particles. The angularity of the particles is varied by increasing the number of faces from 8 (octahedronlike shape) to 596. We find that the shear strength increases with angularity up to a maximum value and saturates as the particles become more angular (below 46 faces). At the same time, the packing fraction increases to a peak value but declines for more angular particles. We analyze the connectivity and anisotropy of the microstructure by considering both the contacts and branch vectors joining particle centers. The increase of the shear strength with angularity is shown to be due to a net increase of the fabric and force anisotropies but at higher particle angularity a rapid falloff of the fabric anisotropy is compensated by an increase of force anisotropy, leading thus to the saturation of shear strength.

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Ref HAL: hal-00782620_v1
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A method of a floating frame of reference that performs splitting of a deformable solid into rigid and deforming parts is presented within the context of discrete element method. The decomposition is made in such a way that the deforming part of the velocity field does not contribute to the motion of the center of mass and to the rotational motion. The corresponding numerical method that computes both rigid and deforming motions is presented and extended to simulation of multi-body dynamics allowing non-smooth contact interactions, such as impacts and friction. Numerical experiments, where the method is compared with a more traditionally used Total Lagrangian method, justify its preference as a more efficient tool for the simulation of assemblies of stiff and massive objects.

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Ref HAL: hal-03260759_v1
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For the purpose of studying the elastic behavior of concrete, a 3-D finite element model is used. A realistic method to represent concrete is adopted. At mesoscopic level, concrete is considered as a bi-phase material where coarse aggregates are dispersed in the mortar paste. The coarse aggregates are represented as spheres and placed randomly in a cylindrical concrete specimen. The aggregate generation should respect the De Larrard model where the minimum paste thickness is taken into consideration. This generation should also respect a specific aggregate size distribution curve. A method to mesh the aggregates and the mortar separately is used. As a result, Different concrete specimens having different aggregate distribution and different aggregate content are generated. At that stage, a compression test is applied to each specimen in order to show the influence of the aggregate generation on the concrete properties. The numerical approach is validated using experimental results issued from previous work and compared to a homogenization method. This model shows interesting results which can be used to predict the elastic behavior of concrete.

Ref HAL: hal-01034277_v1
DOI: 10.1007/978-3-319-05789-7_60
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2 citations
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Numerical simulations of the dynamics of discrete structures in presence of numerous impacts with frictional contacts leads to CPU-intensive large time computations. To deal with these problems, numerical tools have been developed, such as the nonsmooth contact domain decomposition (NSCDD). We present further a distributed version of its algorithm with parallel detection of fine contacts and discuss two possible communication schemes to solve the interface problem. Those improvements allow to study scalability and numerical performances of the method for 2D and 3D granular media.

Commentaires: A draft (preprint) version of the publication is available at http://dd21.inria.fr/pdf/visseqv_contrib.pdf

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Ref HAL: hal-00844252_v1
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