https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Fri, 15 May 2026 02:11:02 GMT 2026-05-15T02:11:02Z http://hdl.handle.net/10985/10214 Implicit implementation and consistent tangent modulus of a viscoplastic model for polymers ACHOUR-RENAULT, Nadia; CHATZIGEORGIOU, George; MERAGHNI, Fodil; CHEMISKY, Yves; FITOUSSI, Joseph In this work, the phenomenological viscoplastic DSGZ model[Duan, Y., Saigal, A., Greif, R., Zimmerman, M. A., 2001. A Uniform Phenomenological Constitutive Model for Glassy and Semicrystalline Polymers. Polymer Engineering and Science 41 (8), 1322-1328], developed for glassy or semi-crystalline polymers, is numerically implemented in a three dimensional framework, following an implicit formulation. The computational methodology is based on the radial return mapping algorithm. This implicit formulation leads to the definition of the consistent tangent modulus which permits the implementation in incremental micromechanical scale transition analysis. The extended model is validated by simulating the polypropylene thermoplastic behavior at various strain rates (from 0:92s-1 to 258s-1) and temperatures (from 20°C to 60°C). The model parameters for the studied material are identified using a heuristic optimization strategy based on genetic algorithm. The capabilities of the new implementation framework are illustrated by performing finite element simulations for multiaxial loading. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10214 2015-01-01T00:00:00Z ACHOUR-RENAULT, Nadia CHATZIGEORGIOU, George MERAGHNI, Fodil CHEMISKY, Yves FITOUSSI, Joseph In this work, the phenomenological viscoplastic DSGZ model[Duan, Y., Saigal, A., Greif, R., Zimmerman, M. A., 2001. A Uniform Phenomenological Constitutive Model for Glassy and Semicrystalline Polymers. Polymer Engineering and Science 41 (8), 1322-1328], developed for glassy or semi-crystalline polymers, is numerically implemented in a three dimensional framework, following an implicit formulation. The computational methodology is based on the radial return mapping algorithm. This implicit formulation leads to the definition of the consistent tangent modulus which permits the implementation in incremental micromechanical scale transition analysis. The extended model is validated by simulating the polypropylene thermoplastic behavior at various strain rates (from 0:92s-1 to 258s-1) and temperatures (from 20°C to 60°C). The model parameters for the studied material are identified using a heuristic optimization strategy based on genetic algorithm. The capabilities of the new implementation framework are illustrated by performing finite element simulations for multiaxial loading. http://hdl.handle.net/10985/10496 Endommagement en fatigue du PA66 renforcé par des fibres de verre courtes : modélisation micromécanique et stratégie d'identification multi - échelles DESPRINGRE, Nicolas; CHEMISKY, Yves; FITOUSSI, Joseph; MERAGHNI, Fodil Cet article présente un modèle micromécanique visco-endommageable pour les composites à matrice thermoplastique renforcée par des fibres de verre courtes et soumis à un chargement en fatigue. L'approche multi-échelles développée est fondée sur la méthode de Mori-Tanaka, modifiée afin d'inclure des inclusions enrobées et l'évolution des mécanismes d'endommagement à l'échelle microscopique. Le modèle développé intègre les cinétiques d'endommagement tout en tenant compte de la viscoélasticité matricielle et de la microstucture. La prise en compte de ces derniers se base sur des travaux précédemment menés par les auteurs sur le PA66/GF30 moulé par injection [3-5]. Des scénarios d'endommagement ont été proposés et regroupent trois mécanismes : la décohésion interfaciale fibre­ matrice, la fissuration matricielle et les ruptures de fibres. Chaque mécanisme d'endommagement est associé à une loi d'évolution dépendant des champs de contraintes à l'échelle microscopique. La loi constitutive du volume élémentaire représentatif est implémentée dans Abaqus en tant qu'User MATerial subroutine. L'identification du modèle se fait par méthodes inverses, bénéficiant ainsi des résultats multi-échelles précédemment obtenus à l'aide de tests in-situ au MEB ou à partir de l'analyse quantitative et qualitative de données issus de la microtomographie. La validation expérimentale est réalisée par des tests en fatigue contrôlés en déformation. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10496 2015-01-01T00:00:00Z DESPRINGRE, Nicolas CHEMISKY, Yves FITOUSSI, Joseph MERAGHNI, Fodil Cet article présente un modèle micromécanique visco-endommageable pour les composites à matrice thermoplastique renforcée par des fibres de verre courtes et soumis à un chargement en fatigue. L'approche multi-échelles développée est fondée sur la méthode de Mori-Tanaka, modifiée afin d'inclure des inclusions enrobées et l'évolution des mécanismes d'endommagement à l'échelle microscopique. Le modèle développé intègre les cinétiques d'endommagement tout en tenant compte de la viscoélasticité matricielle et de la microstucture. La prise en compte de ces derniers se base sur des travaux précédemment menés par les auteurs sur le PA66/GF30 moulé par injection [3-5]. Des scénarios d'endommagement ont été proposés et regroupent trois mécanismes : la décohésion interfaciale fibre­ matrice, la fissuration matricielle et les ruptures de fibres. Chaque mécanisme d'endommagement est associé à une loi d'évolution dépendant des champs de contraintes à l'échelle microscopique. La loi constitutive du volume élémentaire représentatif est implémentée dans Abaqus en tant qu'User MATerial subroutine. L'identification du modèle se fait par méthodes inverses, bénéficiant ainsi des résultats multi-échelles précédemment obtenus à l'aide de tests in-situ au MEB ou à partir de l'analyse quantitative et qualitative de données issus de la microtomographie. La validation expérimentale est réalisée par des tests en fatigue contrôlés en déformation. http://hdl.handle.net/10985/10849 Periodic homogenization for fully coupled thermomechanical modeling of dissipative generalized standard materials CHATZIGEORGIOU, George; CHARALAMBAKIS, Nicolas; CHEMISKY, Yves; MERAGHNI, Fodil The current work deals with periodic thermomechanical composite media, in which the material constituents are considered to obey the generalized standard materials laws. The aim is to provide a proper homogenization framework that takes into account both the equilibrium and the thermodynamics laws in microscale and macroscale levels. The study is based on the asymptotic expansion homogenization technique, which permits to deduce useful results about the general structure of microscale and macroscale energy potentials and constitutive laws. The paper also proposes an incremental, linearized formulation that allows to identify suitable thermomechanical tangent moduli for the macroscale problem. The capabilities of this framework are illustrated with numerical examples on multilayered composites. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/10849 2016-01-01T00:00:00Z CHATZIGEORGIOU, George CHARALAMBAKIS, Nicolas CHEMISKY, Yves MERAGHNI, Fodil The current work deals with periodic thermomechanical composite media, in which the material constituents are considered to obey the generalized standard materials laws. The aim is to provide a proper homogenization framework that takes into account both the equilibrium and the thermodynamics laws in microscale and macroscale levels. The study is based on the asymptotic expansion homogenization technique, which permits to deduce useful results about the general structure of microscale and macroscale energy potentials and constitutive laws. The paper also proposes an incremental, linearized formulation that allows to identify suitable thermomechanical tangent moduli for the macroscale problem. The capabilities of this framework are illustrated with numerical examples on multilayered composites. http://hdl.handle.net/10985/7934 Multiscale fatigue damage characterization in short glass fiber reinforced polyamide-66 ARIF, Muhamad Fatikul; CHEMISKY, Yves; ROBERT, Gilles; FITOUSSI, Joseph; MERAGHNI, Fodil; SAINTIER, Nicolas This paper aims at studying fatigue damage behavior of injection molded 30 wt% short glass fiber reinforced polyamide-66 composite (PA66/GF30). The evolution of dynamic modulus, hysteresis area, cyclic creep and temperature during fatigue tests were analyzed and discussed. Damage analyses by X-ray micro-computed tomography (lCT) technique on interrupted fatigue tests at several percentages of total fatigue life were performed to further understand the damage mechanisms and evolution during fatigue loading. It can be observed that experimental results related to the evolution of dynamic modulus, strain, temperature and energy dissipation are important and consistently complement each other for damage evaluation of PA66/GF30. During fatigue loading, diffuse damage occurs over the entire specimen though the damage does not necessarily exhibit the same level between different locations inside the specimen. The lCT analysis of voids characteristics demonstrates that the damage continuously increases during fatigue loading. The damage is developed notably along fiber interface in the form of fiber/matrix interfacial debonding. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/7934 2014-01-01T00:00:00Z ARIF, Muhamad Fatikul CHEMISKY, Yves ROBERT, Gilles FITOUSSI, Joseph MERAGHNI, Fodil SAINTIER, Nicolas This paper aims at studying fatigue damage behavior of injection molded 30 wt% short glass fiber reinforced polyamide-66 composite (PA66/GF30). The evolution of dynamic modulus, hysteresis area, cyclic creep and temperature during fatigue tests were analyzed and discussed. Damage analyses by X-ray micro-computed tomography (lCT) technique on interrupted fatigue tests at several percentages of total fatigue life were performed to further understand the damage mechanisms and evolution during fatigue loading. It can be observed that experimental results related to the evolution of dynamic modulus, strain, temperature and energy dissipation are important and consistently complement each other for damage evaluation of PA66/GF30. During fatigue loading, diffuse damage occurs over the entire specimen though the damage does not necessarily exhibit the same level between different locations inside the specimen. The lCT analysis of voids characteristics demonstrates that the damage continuously increases during fatigue loading. The damage is developed notably along fiber interface in the form of fiber/matrix interfacial debonding. http://hdl.handle.net/10985/10354 Fatigue damage in short glass fiber reinforced PA66: Micromechanical modeling and multiscale identification approach DESPRINGRE, Nicolas; CHEMISKY, Yves; MERAGHNI, Fodil; FITOUSSI, Joseph; ROBERT, Gilles The paper presents a new micromechanical high cycle fatigue visco-damage model for short glass fiber reinforced thermoplastic composites, namely: PA66/GF30. This material, extensively used for automotive applications, has a specific microstructure which is induced by the injection process. The multi-scale developed approach is a modified Mori-Tanaka method that includes coated reinforcements and the evolution of micro-scale damage processes. The description of the damage processes is based on the experimental investigations of damage mechanisms previously performed by the authors and presented elsewhere [M.F. Arif et al. "In situ damage mechanisms investigation of PA66/GF30 composite: Effect of relative humidity." Composites Part B: Engineering, Volume 61: 55-65, 2014]. Damage chronologies have been proposed involving three different local degradation processes: fiber-matrix interface debonding/coating degradation, matrix microcracking and fiber breakage. Their occurrence strongly depends on the microstructure and the moisture content. The developed model integrates these damage kinetics and accounts for the complex matrix viscoelasticity and the reinforcement orientation distributions induced by the process. Each damage mechanism is introduced through an evolution law involving local stress fields computed at the microscale. The developed constitutive law at the representative volume element scale is implemented into the finite element code Abaqus using a User MATerial subroutine. The model identification is performed via reverse engineering, taking advantage of the multiscale experimental results: in-situ SEM tests as well as quantitative and qualitative μCT investigations. Experimental validation is achieved using high cycle strain controlled fatigue tests. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10354 2015-01-01T00:00:00Z DESPRINGRE, Nicolas CHEMISKY, Yves MERAGHNI, Fodil FITOUSSI, Joseph ROBERT, Gilles The paper presents a new micromechanical high cycle fatigue visco-damage model for short glass fiber reinforced thermoplastic composites, namely: PA66/GF30. This material, extensively used for automotive applications, has a specific microstructure which is induced by the injection process. The multi-scale developed approach is a modified Mori-Tanaka method that includes coated reinforcements and the evolution of micro-scale damage processes. The description of the damage processes is based on the experimental investigations of damage mechanisms previously performed by the authors and presented elsewhere [M.F. Arif et al. "In situ damage mechanisms investigation of PA66/GF30 composite: Effect of relative humidity." Composites Part B: Engineering, Volume 61: 55-65, 2014]. Damage chronologies have been proposed involving three different local degradation processes: fiber-matrix interface debonding/coating degradation, matrix microcracking and fiber breakage. Their occurrence strongly depends on the microstructure and the moisture content. The developed model integrates these damage kinetics and accounts for the complex matrix viscoelasticity and the reinforcement orientation distributions induced by the process. Each damage mechanism is introduced through an evolution law involving local stress fields computed at the microscale. The developed constitutive law at the representative volume element scale is implemented into the finite element code Abaqus using a User MATerial subroutine. The model identification is performed via reverse engineering, taking advantage of the multiscale experimental results: in-situ SEM tests as well as quantitative and qualitative μCT investigations. Experimental validation is achieved using high cycle strain controlled fatigue tests. http://hdl.handle.net/10985/10575 Identification and interpretation of material parameters of a shape memory alloy (SMA) model PIOTROWSKI, Boris; CHEMISKY, Yves; MERAGHNI, Fodil; ECHCHORFI, Rachid; BOURGEOIS, Nadine; PATOOR, Etienne The thermomechanical behavior of Shape Memory Alloys (SMAs) is described by many micromechanical and phenomenological models. The first ones have material parameters whose physical meaning is based on the crystallography of the phase transformation related to the studied alloy. In contrast, phenomenological models often have material parameters whose physical meaning is not obvious and that makes them difficult to identify, some of which are based on mathematical considerations. In this paper, we propose to use the formulation of the phenomenological model of Chemisky et al., and to consider the particular case of a superelastic SMA. In this case, the constitutive equation should be easily expressed analytically through the strain tensor as a function of applied load direction and material parameters. The behavior is then characterized by a complete and proportional loading. This analytical model contains 7 material parameters, 1 related to the elasticity and 6 to the phase transformation. Based on several isothermal tensile tests at various temperatures, material parameters of this model are identified using the Levenberg-Marquardt algorithm and an analytical calculation of the sensitivity matrix. Their physical meaning and their influence on the thermomechanical behavior of the studied alloy are highlighted and discussed. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/10575 2013-01-01T00:00:00Z PIOTROWSKI, Boris CHEMISKY, Yves MERAGHNI, Fodil ECHCHORFI, Rachid BOURGEOIS, Nadine PATOOR, Etienne The thermomechanical behavior of Shape Memory Alloys (SMAs) is described by many micromechanical and phenomenological models. The first ones have material parameters whose physical meaning is based on the crystallography of the phase transformation related to the studied alloy. In contrast, phenomenological models often have material parameters whose physical meaning is not obvious and that makes them difficult to identify, some of which are based on mathematical considerations. In this paper, we propose to use the formulation of the phenomenological model of Chemisky et al., and to consider the particular case of a superelastic SMA. In this case, the constitutive equation should be easily expressed analytically through the strain tensor as a function of applied load direction and material parameters. The behavior is then characterized by a complete and proportional loading. This analytical model contains 7 material parameters, 1 related to the elasticity and 6 to the phase transformation. Based on several isothermal tensile tests at various temperatures, material parameters of this model are identified using the Levenberg-Marquardt algorithm and an analytical calculation of the sensitivity matrix. Their physical meaning and their influence on the thermomechanical behavior of the studied alloy are highlighted and discussed. http://hdl.handle.net/10985/10837 Identification of Model Parameter for the Simulation of SMA Structures Using Full Field Measurements CHEMISKY, Yves; MERAGHNI, Fodil; BOURGEOIS, Nadine; CORNELL, Stephen; ECHCHORFI, Rachid; PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, where the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from multiaxial and heterogeneous tests carried out on specimens with the same thermomechanical loading history. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best matches experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel in a supercomputer to reduce the time necessary to identify the set of identified parameters. The major features of this new algorithm is its ability to identify material parameters of the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10837 2015-01-01T00:00:00Z CHEMISKY, Yves MERAGHNI, Fodil BOURGEOIS, Nadine CORNELL, Stephen ECHCHORFI, Rachid PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, where the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from multiaxial and heterogeneous tests carried out on specimens with the same thermomechanical loading history. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best matches experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel in a supercomputer to reduce the time necessary to identify the set of identified parameters. The major features of this new algorithm is its ability to identify material parameters of the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. http://hdl.handle.net/10985/9969 Analysis of the deformation paths and thermomechanical parameter identification of a shape memory alloy using digital image correlation over heterogeneous tests CHEMISKY, Yves; MERAGHNI, Fodil; BOURGEOIS, Nadine; CORNELL, Stephen; ECHCHORFI, Rachid; PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, for which the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from tests performed on specimens with non-uniform geometry, which induce heterogeneous strain fields carried out on specimens with the same thermomechanical loading history. The digital image correlation technique is employed to measure the strain fields on the surface of the specimen and to analyze the strain paths of chosen points. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best match experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel using a supercomputer to reduce the time necessary to identify the set of model parameters. The major features of this new algorithm is its ability to identify the material parameters which describe the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9969 2015-01-01T00:00:00Z CHEMISKY, Yves MERAGHNI, Fodil BOURGEOIS, Nadine CORNELL, Stephen ECHCHORFI, Rachid PATOOR, Etienne With the design of new devices with complex geometry and to take advantage of their large recoverable strains, shape memory alloys components (SMA) are increasingly subjected to multiaxial loadings. The development process of SMA devices requires the prediction of their thermomechanical response, for which the calibration of the material parameters for the numerical model is an important step. In this work, the parameters of a phenomenological model are extracted from tests performed on specimens with non-uniform geometry, which induce heterogeneous strain fields carried out on specimens with the same thermomechanical loading history. The digital image correlation technique is employed to measure the strain fields on the surface of the specimen and to analyze the strain paths of chosen points. Finite element analysis enables the computation of numerical strain fields using a thermodynamical constitutive model for shape memory alloys previously implemented in a finite element code. The strain fields computed numerically are compared with experimental ones obtained by DIC to find the model parameters which best match experimental measurements using a newly developed parallelized mixed genetic/gradient-based optimization algorithm. These numerical simulations are carried out in parallel using a supercomputer to reduce the time necessary to identify the set of model parameters. The major features of this new algorithm is its ability to identify the material parameters which describe the thermomechanical behavior of shape memory alloys from full-field measurements for various loading conditions (different temperatures, multiaxial behavior, heterogeneous test configurations). It is demonstrated that model parameters for the simulation of SMA structures are thus obtained based on a reduced number of heterogeneous tests at different temperatures. http://hdl.handle.net/10985/11150 Linearization and implementation of venu model in small strain theory for polyamide 6.6 ANAGNOSTOU, Dimitrios; CHATZIGEORGIOU, George; BOUVARD, Jean-Luc; CHEMISKY, Yves; MERAGHNI, Fodil; BILLON, Noelle The so-called VENU model is a visco-hyperelastic constitutive model, designed for amorphous rubbery polymers, which is based on an original approach initially developed by N. Billon (J. Appl. Polym. Sci. 125:4390-4401, 2012) and extended by A. Maurel-Pantel et al. (Int. J. Plast. 67:102126, 2015) to three-dimensional thermomechanical framework. In the aforementioned references, the constitutive equations and thermodynamical framework are presented within large deformation theory. However, in fatigue tests of polymeric composites significant temperature gradients are noticed despite the fact that the measured strains are within the small strain theory. In addition, well established techniques and tools of micromechanics for polymeric composites are applicable in small deformation regions. These observations render important the reduction of the VENU model in the case of linear strains. Here, a method is proposed for the reduction of the VENU model to small strain theory. A proper numerical scheme is also provided, based on the so-called return-mapping algorithm. The model capabilities are illustrated by comparing numerical calculations with available experimental data for polyamide 66. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/11150 2016-01-01T00:00:00Z ANAGNOSTOU, Dimitrios CHATZIGEORGIOU, George BOUVARD, Jean-Luc CHEMISKY, Yves MERAGHNI, Fodil BILLON, Noelle The so-called VENU model is a visco-hyperelastic constitutive model, designed for amorphous rubbery polymers, which is based on an original approach initially developed by N. Billon (J. Appl. Polym. Sci. 125:4390-4401, 2012) and extended by A. Maurel-Pantel et al. (Int. J. Plast. 67:102126, 2015) to three-dimensional thermomechanical framework. In the aforementioned references, the constitutive equations and thermodynamical framework are presented within large deformation theory. However, in fatigue tests of polymeric composites significant temperature gradients are noticed despite the fact that the measured strains are within the small strain theory. In addition, well established techniques and tools of micromechanics for polymeric composites are applicable in small deformation regions. These observations render important the reduction of the VENU model in the case of linear strains. Here, a method is proposed for the reduction of the VENU model to small strain theory. A proper numerical scheme is also provided, based on the so-called return-mapping algorithm. The model capabilities are illustrated by comparing numerical calculations with available experimental data for polyamide 66. 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.