Nonlinear continuum damage models for ceramic matrix composites with significant in plane ply anisotropy

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Approximation and definition of state variables for a comprehensive description of damage for ceramic matrix composites

International audienceOver the past decades, non-linear models describing damage and fracture of architectured materials have highly progressed, taking into account varied scenarios of degradation under complex multi-axial loadings. Many of these models remain expansive to numericaly handle and difficult to understand. In parallel, full-field measurement has brought a large quantity of data. A challenging task for the researcher is extracting information from that data quantity. The extraction relies on state variables and the associated energetic potentials. This paper will present the automatic definition of state variables in two situations. The first situation corresponds to a local case where the objective is simplifying an existing constitutive relation. As an example, an anisotropic tensorial damage model developed is simplified to a scalar damage model. Several choices of approximations and errors will be discussed. The second situation corresponds to a structural case where the objective is to simplify fields. The developed point of view relies on local pattern extraction associated with a PUM/GFEM method. After the introduction of this method, an automatic building method is evaluate

A modeling framework, accounting for competing degradation/healing mechanisms, for the prediction of the long term mechanical behavior of CMCs.

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Stratégie de calcul et utilisation de séries de Fourier pour les tubes composites dégradés

During the manufacturing of composite pipes (carbon/epoxy), some defects appear (delamination, cracking). The problem is then to decide whether a pipe is usable or must be rejected. This work consists in the development of a numerical tool allowing the use of a damage mesomodel .Lors de la fabrication de tubes composites (carbone/epoxy), des défauts apparaissent (délaminage, fissuration). Le problème est alors de décider si un tube est apte au service. Ce travail consiste à mettre en place un outil numérique dédié permettant l'utilisation d'un méso-modèle d'endommagement à l'échelle du pli

Accounting for frictional contact in an anisotropic damage model based on compliance tensorial variables, illustration on ceramic matrix composites

International audienceCeramic matrix composites have good thermomechanical properties at high or very high temperatures. The modeling of the crack networks associated to the degradation of such composites using damage mechanics is not straightforward. The main reason is the presence of a crack network mainly oriented by the loading direction, which is a priori unknown. To model this, compliance tensorial damage variables are used in a thermodynamic potential able to account for crack closure effects (unilateral contact). The damage kinematic is initially completely free and imposed by the evolution laws. The key point of the present paper is to account for friction in such cracks that can result in an apparent activation/deactivation of the shear damage. The initial model is enriched with an inelastic strain and a friction law. The plasticity criterion is expressed only using tensorial variables. The model is identified and illustrated on multiaxial data obtained at ONERA on tubes loaded in tension and torsion

5.8 Modeling Mechanical Behavior of Ceramic Matrix Composites

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