Ref HAL: hal-00806858_v1
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Discrete element methods (DEM) constitute an important tool for the study of granular matter and divided materials or structures. Basically DEM model a material or a structure at the grain scale and are able to describe various complex behaviors (flow, localization of deformations, fracture, dissipation, etc) which can't be properly represented by continuum approach even with advanced constitutive model based on a huge number of parameters.

Ref HAL: hal-00806948_v1
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Numerical techniques are more and more sophisticated and each kind of method have its own field of applications. Concerning multi-physics analysis, it is more and more relevant to be able to combine different methods to solve complex problems.

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Ref HAL: hal-00806626_v1
DOI: 10.3166/ejcm.19.389-417
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8 citations
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Cet article présente d’une part, une stratégie de modélisation dédiée à la simulation micromécanique des interactions entre corps, et, d’autre part, sa mise en oeuvre numérique. Cette stratégie repose sur une formulation de type décomposition de domaines d’une méthode multicorps périodique dans le cadre de l’approche NonSmooth Contact Dynamics de Moreau (1988). Les potentialités de cette méthode sont illustrées par la complexité des interactions possibles : interactions entre éléments d’une discrétisation, entre corps discrétisés ou rigides, en compression (contact) lente ou sous impact, en glissement (frottement) ou en traction (fissuration-rupture), etc. La plateforme numérique associée, Xper, repose sur une architecture orientée objet composée de bibliothèques indépendantes. La pertinence numérique de l’approche est illustrée sur des exemples de fissuration de matériaux hétérogènes.

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Ref HAL: hal-00796534_v1
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Wood is a porous, hygroscopic, anisotropic and non homogeneous biopolymer. It is classified as a viscoelastic material with mechanical properties depending on temperature and moisture content. The effect of creep is an important factor for the design and the durability of timber structures. Creep evolution results from the interaction between mechanical stress and moisture content variations.

Commentaires: session 'Computational Material Modeling of Wood and Wood Products'

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Ref HAL: inria-00522352_v1
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We present in this work a modeling approach and an associated numerical strategy both devoted to complex mechanical surface interactions. This approach together with the dedicated numerical strategy are referred as Non Smooth Fracture Dynamics (NSFD). From an applied point of view, this work concerns the comprehension, the prediction and the numerical simulation of dynamic fracture for a wide variety of materials and structures. The main contribution is the ability to predict an entire fracture process: crack initiation, growth, propagation of microcracks, coalescence, propagation of a microcrack, final rupture and post fracture behavior (e.g. frictional contact between created fragments after fracture).

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Ref HAL: hal-00502831_v1
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Painted wood panels of cultural heritage (furnitures, musical instruments, paintings...) are often sensitive to several loadings such as mechanical restraint, as well as humidity and temperature cycles due to the hygrothermal variations of the surrounding environment. To improve preventive conservation and to guide restoration acts on wooden artworks, virtual testing via numerical simulation is necessary to assess a risk analysis, in order to predict if the object will remain safe under various scenarii. We focus herein on a numerical strategy, belonging to the family of partitioning schemes, to solve the coupled problem of thermo-hygro-mechanical response of wood structures. A dedicated code is used for thermal and moisture transfer, while a structural code is used for the mechanical response. With the modularity of a partitioning scheme, the code coupling is used with minimized intrusion, when compared to monolithic codes. Our aim is to assess the risk resulting from the change of ambient conditions and make the appropriate decision for preventive conservation. Therefore we propose a method to evaluate the riskiness of some likely-to-happen climate variations, and conclude on possible interventions on the panel.

Ref HAL: hal-00502827_v1
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Painted wood panels of cultural heritage (furnitures, musical instruments, paintings...) are often sensitive to several loadings such as mechanical restraint, as well as humidity and temperature cycles due to the hygrothermal variations of the surrounding environment. To improve preventive conservation and to guide restoration acts on wooden artworks, virtual testing via numerical simulation is necessary to assess a risk analysis, in order to predict if the object will remain safe under various scenarii. We focus herein on a numerical strategy, belonging to the family of partitioning schemes, to solve the coupled problem of thermo-hygro-mechanical response of wood structures. Wood material is sensitive to moisture, and this dependency is itself influenced with the temperature. An example of a rheological model (depending on moisture and temperature) is an orthotropic Generalized Kelvin-Voith (GKV) model with several stages: elastic, swelling/shrinkage, mechano-sorptive, and two visco-elastic stages. A dedicated code is used for thermal and moisture transfer, while a structural code is used for the mechanical response. With the modularity of a partitioning scheme, the code coupling is used with minimized intrusion, when compared to monolithic codes.

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