A multi-model X-FEM strategy dedicated to frictional crack growth under cyclic fretting fatigue loadings.

International audienceA 2D X-FEM/LATIN numerical model (eXtended Finite Element Method/Large Time Increment method) is proposed in this paper for the analysis of fretting fatigue problems and the simulation of the crack propagation under such loadings. The half-analytical two-body contact analysis allows to capture accurately the pressure and the cyclic tractions exerted at the interface that induce non-proportional multi-axial loading. These distributions are then used as input data for determining critical location for crack initiation and crack inclination based on Dang Van's criterion. The frictional contact conditions of the fretting fatigue cracks have an important impact on the crack behaviour. In this respect, contact with friction between the crack faces is finely modeled within the X-FEM frame. The obtained results are compared and validated with a half-analytical reference model. The numerical simulations reveal the robustness and the efficiency of the proposed approach for a wide range of fretting loadings and friction coefficients values along crack faces. The crack growth directions are then predicted accurately based on the use of criteria adapted to multi-axial non-proportional fatigue. Four cases dealing with crack propagation are then presented. It is shown how the crack length, the tangential loading modify the crack path during the propagation process

Experimental and numerical analysis of fretting crack formation based on 3D X-FEM frictional contact fatigue crack model

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Simulation tridimensionnelle multi-échelle de la propagation de fissures expérimentales sous chargement de fretting fatigue par la méthode des éléments finis étendus

La maîtrise des mécanismes de rupture dans les problèmes de fretting requiert une analyse pluridisciplinaire des différents phénomènes physiques couplés pour prendre en compte les effets globaux et locaux, les sollicitations multiaxiales non proportionnelles et les conditions de contact interfacial avec frottement. Un modèle tridimensionnel éléments finis étendus mufti-échelles dédié au contact avec frottement entre les faces de la fissure est proposé. Une formulation faible mixte à trois champs permet une définition intrinsèque de la fissure avec sa propre discrétisation indépendante du maillage de la structure. Un solveur stabilisé adapté de la méthode LATIN est implémenté. Les propriétés de stabilité et les performances du modèle sont illustrées dans plusieurs exemples bidimensionnels et tridimensionnels. Le modèle est validé par comparaison avec un code éléments finis industriel. Une stratégie mufti-modèles globale basée sur l'analyse expérimentale et la simulation numérique de la propagation des fissures est développée afin de prédire la durée de vie de composants en frelling fatigue. Des essais de fretting fatigue sont réalisés afin d'analyser l'amorçage et la propagation de fissures. Les sollicilatrons tribologiques au cours du cycle sont déterminées par la résolution du contact deux-corps. La prédiction du risque d'amorçage des fissures est conduite. Ces résultats sont utilisés comme données d'entrée pour la modélisation X-FEM des essais de frettlng bidimensionnels et tridimensionnels. La simulation de la propagation des fissures est réalisée à l'aide de critères de propagation multiaxiale non proportionnels et d'une loi de propagation expérimentale.Fretting fatigue crack modelling in a predictive approach requires a multi-physical analysis of the numerous global and local affects such as the mufti-axial non proportional loading and the frictional contact conditions between the crack faces. A 30 multi-scale extended finite element model dedicated to frictional crack growth is developed. The use of a three-field weak formulation allows an intrinsic definition of the crack interface with its own discretization independent from the structure mesh. A stabilized solver based on the LATIN method is proposed. Two- dimensional and three-dimensional examples illustrate the stability and the performances of the model. It is validated using comparisons with an industrial finite element code. A global mufti-model strategy based on experimental and numerical crack analysis is proposed to predict fife time of components subjected to fretting fatigue. Fretting tests are performed ta analyse crack initiation and crack growth. The two-body contact loading is computed. Crack risk prediction is conducted. These results are used as input data for 20 and 30 numerical X-FEM modelling of the fretting test. Crack growth simulation is performed using mufti-axial fatigue criteria and experimental crack growth lawVILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceF

A two-scale extended finite element method for modeling 3D crack growth with interfacial contact.

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A stable 3D multi-scale X-FEM frictional contact model for crack growth simulation

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A stable 3D multi-scale X-FEM frictional contact model for crack growth simulation

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3D two scale X-FEM crack model with interfacial frictional contact: Apllication to fretting fatigue

International audienceA global approach coupling experiments and numerical modeling is proposed to enhance crack prediction. Fretting tests have been conducted under conditions leading to crack formation. Three dimensional crack shapes have been reconstructed from metallographic cross-sections and described with level set functions. They are then used as input data in 3D two-scale X-FEM model detailed in this paper. Frictional contact conditions holding between the crack faces are accounting for. The methodology developed to describe those contact conditions at the pertinent scale is detailed.A 3D fretting fatigue test is modeled to illustrate the coupling between experiments and numerical modeling

Fretting fatigue crack growth simulation based on a combined experimental and xfem strategy

International audienceA combined experimental and numerical study is presented in order to predict fretting crack propagation. It rests on 2D and 3D fretting tests, with carefully controlled loading conditions leading to cracking as the main material response, the extraction of 2D and 3D crack geometry from post-mortem cross-sections, a three-dimensional X-FEM model based on a three field weak formulation accounting for 3D non-planar frictional crack and the level set formalism authorising a direct use of actual reconstructed crack shape, the stress intensity factors quantification, a mixed mode Paris law identification and finally the crack growth simulation. The 2D fretting tests are numerically simulated. The mixed mode crack growth law identified is then used to simulate the fretting crack growth. A very good agreement with experimental results is obtained. Then 3D fretting tests are simulated and the crack fronts are compared with actual ones