https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Thu, 14 May 2026 10:12:23 GMT 2026-05-14T10:12:23Z http://hdl.handle.net/10985/11144 Micromechanical modeling of damage and load transfer in particulate composites with partially debonded interface DESPRINGRE, Nicolas; CHEMISKY, Yves; BONNAY, Kevin; MERAGHNI, Fodil A new micromechanical damage model accounting for progressive interface debonding is developed for composite materials. It consists of an original evolution law of the damage at the interface and an appropriate load transfer law at the matrix-fiber interface integrated into a generalized incremental Mori–Tanaka homogenization scheme. The interface damage evolution is driven by the interfacial stress state while the load transfer is obtained from a new model inspired by the shear lag model. Specifically, such damage evolution is supported by experimental microscopic observations for short glass fiber reinforced polyamide-66. The proposed model is validated based on numerical reference solutions provided from finite element analyses of a representative unit cell of a composite, where imperfect interfaces are represented using cohesive elements. A further comparison with experimental data proves that the proposed model is an alternative to micromechanical models involving weak interfaces in the case of spherical reinforcements. It is shown that the proposed model is able to accurately reproduce the non-linear effective response of composite materials for a broad range of reinforcement shapes, including spherical particles and matrix mechanical properties. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/11144 2016-01-01T00:00:00Z DESPRINGRE, Nicolas CHEMISKY, Yves BONNAY, Kevin MERAGHNI, Fodil A new micromechanical damage model accounting for progressive interface debonding is developed for composite materials. It consists of an original evolution law of the damage at the interface and an appropriate load transfer law at the matrix-fiber interface integrated into a generalized incremental Mori–Tanaka homogenization scheme. The interface damage evolution is driven by the interfacial stress state while the load transfer is obtained from a new model inspired by the shear lag model. Specifically, such damage evolution is supported by experimental microscopic observations for short glass fiber reinforced polyamide-66. The proposed model is validated based on numerical reference solutions provided from finite element analyses of a representative unit cell of a composite, where imperfect interfaces are represented using cohesive elements. A further comparison with experimental data proves that the proposed model is an alternative to micromechanical models involving weak interfaces in the case of spherical reinforcements. It is shown that the proposed model is able to accurately reproduce the non-linear effective response of composite materials for a broad range of reinforcement shapes, including spherical particles and matrix mechanical properties. http://hdl.handle.net/10985/11174 Interfacial damage and load transfermodeling in short fiber reinforced composites BONNAY, Kevin; DESPRINGRE, Nicolas; CHEMISKY, Yves; MERAGHNI, Fodil Due to the compromise between their thermomechanical properties and low density, Short Fiber Reinforced Polyamides (SFRP) present a good alternative to metals for automotive structural components. The microstructure of such materials, combined with the matrix sensitivity to environmental conditions, has a strong impact on their overall behavior and the related damage. A new multi-scale modelling strategy is proposed, based on the experimental observations of interfacial damage evolution for PA66-GF30 composites. Three main key-points have been integrated to this approach: an original damage evolution law at the interface, an appropriate load transfer law at the matrix-fiber interface, and a homogenization strategy founded on the generalized Mori-Tanaka scheme. The damage evolution law is driven by a local probabilistic criterion based on the interfacial stress field estimation. This type of evolution depends on the maximal local damage rate at the fiber/matrix interface, determined from a numerical evaluation at several points of the interface surrounding the inclusion. It is then coupled with a load transfer law formulated according to a modified shear lag model (SLM). The developed model is assessed with a finite element (FE) computation integrating cohesive elements at the matrix-fiber interface. The FE unit cell consists in a periodic media (hexagonal array) with periodic boundary conditions. The fiber-matrix interface integrates cohesive elements, with a cohesive law driven by a Paulino-Park-Roesler (PPR) potential-based formulation. The latter has been proven to be suitable for the 3D modeling of interface in reinforced composites. The proposed approach is able to accurately capture the non-linear behavior of short fiber reinforced polyamide composites accounting for interfacial damage. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/11174 2016-01-01T00:00:00Z BONNAY, Kevin DESPRINGRE, Nicolas CHEMISKY, Yves MERAGHNI, Fodil Due to the compromise between their thermomechanical properties and low density, Short Fiber Reinforced Polyamides (SFRP) present a good alternative to metals for automotive structural components. The microstructure of such materials, combined with the matrix sensitivity to environmental conditions, has a strong impact on their overall behavior and the related damage. A new multi-scale modelling strategy is proposed, based on the experimental observations of interfacial damage evolution for PA66-GF30 composites. Three main key-points have been integrated to this approach: an original damage evolution law at the interface, an appropriate load transfer law at the matrix-fiber interface, and a homogenization strategy founded on the generalized Mori-Tanaka scheme. The damage evolution law is driven by a local probabilistic criterion based on the interfacial stress field estimation. This type of evolution depends on the maximal local damage rate at the fiber/matrix interface, determined from a numerical evaluation at several points of the interface surrounding the inclusion. It is then coupled with a load transfer law formulated according to a modified shear lag model (SLM). The developed model is assessed with a finite element (FE) computation integrating cohesive elements at the matrix-fiber interface. The FE unit cell consists in a periodic media (hexagonal array) with periodic boundary conditions. The fiber-matrix interface integrates cohesive elements, with a cohesive law driven by a Paulino-Park-Roesler (PPR) potential-based formulation. The latter has been proven to be suitable for the 3D modeling of interface in reinforced composites. The proposed approach is able to accurately capture the non-linear behavior of short fiber reinforced polyamide composites accounting for interfacial damage. http://hdl.handle.net/10985/10840 Effective properties of multiphase composites made of elastic materials with hierarchical structure TSALIS, Dimitrios; BONNAY, Kevin; CHATZIGEORGIOU, George; CHARALAMBAKIS, Nicolas In this paper, the analytical solution of the multi - step homogenization problem for multi - rank composites with generalized periodicity made of elastic materials is presented. The proposed homogenization scheme may be combined with computational homogenization for solving more complex microstructures. Three numerical examples are presented, concerning locally periodic stratified materials, matrices with wavy layers and wavy fiber reinforced composites. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10840 2015-01-01T00:00:00Z TSALIS, Dimitrios BONNAY, Kevin CHATZIGEORGIOU, George CHARALAMBAKIS, Nicolas In this paper, the analytical solution of the multi - step homogenization problem for multi - rank composites with generalized periodicity made of elastic materials is presented. The proposed homogenization scheme may be combined with computational homogenization for solving more complex microstructures. Three numerical examples are presented, concerning locally periodic stratified materials, matrices with wavy layers and wavy fiber reinforced composites. http://hdl.handle.net/10985/11998 Modélisation multi-échelles en viscoplasticité endommageable de composites thermoplastiques renforcés par des fibres discontinues; Multiscale modeling in viscoplasticity coupled to damage of discontinuous fibers reinforced thermoplastic composites ACHOUR, Nadia; CHATZIGEORGIOU, George; BONNAY, Kevin; MERAGHNI, Fodil Un nouveau modèle multi-échelles en régime viscoplastique endommageable est développé pour un composite à matrice polypropylène renforcé par des fibres de verre courtes. Basé sur l’approche en champs moyens de Mori Tanaka, il intègre une matrice viscoplastique modélisée par un modèle phénoménologique nommé par ses auteurs DSGZ et des fibres de verres modélisées par un comportement élastique linéaire. Le modèle multi-échelles permet d’intégrer la microstructure du composite préalablement caractérisée par la microtomographie aux rayons X. L’introduction de la matrice viscoplastique dans le modèle de Mori Tanaka est rendu possible grâce à une implémentation par intégration implicite du modèle qui permet d’obtenir le module tangent nécessaire au mod èle d’homogénéisation. L’endommagement du matériau est intégré à travers du mécanisme de décohésion de l’interface fibre/ matrice. Ce mécanisme d’endommagement est modélisé par une loi cumulative de type Weibull. La dépendance à la vitesse de déformation du composite observée lors des essais dynamiques est intégrée au moyen de la prise en compte de la viscosité de la matrice. Les paramètres du modèle sont identifiés par une méthode inverse sur la base d’essais de traction à différentes vitesses et pour différentes orientations d’éprouvettes. Le modèle développé a été validé par comparaison avec des essais de traction.; A new multi-scale model accounting for viscoplasticity and damage is developed for a short-fiber reinforced polypropylene composite. In the proposed Mori Tanaka homogenization approach, the viscoplastic matrix is modeled through a phenomenological constitutive law named by its authors DSGZ and the glass fibers are considered as linear elastic. The multiscale model accounts for the composite’s microstructure, which is previously characterized by X-ray microtomography. The introduction of the viscoplastic matrix into the Mori Tanaka method is achieved thanks to an implicit integration scheme that enables the estimation of the necessary tangent modulus. The material damage mechanism is considered at the matrix/fiber interface and is modeled by a Weibull-type cumulative law. The rate dependence of the composite observed in the dynamic tests is integrated through the viscous behavior of the matrix. The model parameters are identified by an inverse method using tensile tests at different strain rates and for different orientations of samples. The model is subsequently validated by comparison with high speed tensile tests. Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10985/11998 2017-01-01T00:00:00Z ACHOUR, Nadia CHATZIGEORGIOU, George BONNAY, Kevin MERAGHNI, Fodil Un nouveau modèle multi-échelles en régime viscoplastique endommageable est développé pour un composite à matrice polypropylène renforcé par des fibres de verre courtes. Basé sur l’approche en champs moyens de Mori Tanaka, il intègre une matrice viscoplastique modélisée par un modèle phénoménologique nommé par ses auteurs DSGZ et des fibres de verres modélisées par un comportement élastique linéaire. Le modèle multi-échelles permet d’intégrer la microstructure du composite préalablement caractérisée par la microtomographie aux rayons X. L’introduction de la matrice viscoplastique dans le modèle de Mori Tanaka est rendu possible grâce à une implémentation par intégration implicite du modèle qui permet d’obtenir le module tangent nécessaire au mod èle d’homogénéisation. L’endommagement du matériau est intégré à travers du mécanisme de décohésion de l’interface fibre/ matrice. Ce mécanisme d’endommagement est modélisé par une loi cumulative de type Weibull. La dépendance à la vitesse de déformation du composite observée lors des essais dynamiques est intégrée au moyen de la prise en compte de la viscosité de la matrice. Les paramètres du modèle sont identifiés par une méthode inverse sur la base d’essais de traction à différentes vitesses et pour différentes orientations d’éprouvettes. Le modèle développé a été validé par comparaison avec des essais de traction. A new multi-scale model accounting for viscoplasticity and damage is developed for a short-fiber reinforced polypropylene composite. In the proposed Mori Tanaka homogenization approach, the viscoplastic matrix is modeled through a phenomenological constitutive law named by its authors DSGZ and the glass fibers are considered as linear elastic. The multiscale model accounts for the composite’s microstructure, which is previously characterized by X-ray microtomography. The introduction of the viscoplastic matrix into the Mori Tanaka method is achieved thanks to an implicit integration scheme that enables the estimation of the necessary tangent modulus. The material damage mechanism is considered at the matrix/fiber interface and is modeled by a Weibull-type cumulative law. The rate dependence of the composite observed in the dynamic tests is integrated through the viscous behavior of the matrix. The model parameters are identified by an inverse method using tensile tests at different strain rates and for different orientations of samples. The model is subsequently validated by comparison with high speed tensile tests. http://hdl.handle.net/10985/10366 Multiscale homogenization of multilayered structures TSALIS, Dimitrios; BONNAY, Kevin; CHATZIGEORGIOU, George; CHARALAMBAKIS, Nicolas In this paper, the analytical solution of the multiple - step homogenization problem for multi - rank composites with generalized periodicity made of elastic materials is presented. The proposed homogenization scheme is combined with computational homogenization for solving more complex microstructures. Two numerical examples arepresented, concerning a “chevron” composite and a wavy fiber reinforced composite. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10366 2015-01-01T00:00:00Z TSALIS, Dimitrios BONNAY, Kevin CHATZIGEORGIOU, George CHARALAMBAKIS, Nicolas In this paper, the analytical solution of the multiple - step homogenization problem for multi - rank composites with generalized periodicity made of elastic materials is presented. The proposed homogenization scheme is combined with computational homogenization for solving more complex microstructures. Two numerical examples arepresented, concerning a “chevron” composite and a wavy fiber reinforced composite.