37 results on '"Fréour, Sylvain"'
Search Results
2. Statistical properties of effective elastic moduli of random cubic polycrystals
- Author
-
Sheng Ningyue, Khazaie Shahram, Chevreuil Mathilde, and Fréour Sylvain
- Subjects
polycrystals ,random fields ,effective elastic moduli ,karhonen–loève expansion ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
The homogenized elastic properties of polycrystals depend on the grain morphology and crystallographic orientations. For simplification purposes, the orientations of the grains are usually considered three independent Euler angles. However, experimental investigations reveal spatial correlations in these angles. The Karhunen–Loève expansion is used to generate random fields of Euler angles having exponential kernel functions with varying correlation lengths. The effective elastic moduli for numerically generated statistically equiaxed cubic polycrystals are estimated via the classical Eshelby–Kröner Self-Consistent homogenization model. The influence of the correlation lengths of the orientations’ random fields on the statistical properties of the effective elastic moduli has been investigated. Our results show that spatially correlated Euler angles could increase the variability of the homogenized elastic properties compared to the ones having uncorrelated Euler angles. Nevertheless, using independent random variables for Euler angles remains valid when correlation lengths are close to the average grain size.
- Published
- 2023
- Full Text
- View/download PDF
3. A numerical model for coupling hygro-mechanical phenomena in composite materials
- Author
-
International Conference on Composite Materials (22nd : 2019 : Melboune, VIC.), Khazaie, Shahram, Mbacke, Mamadou A, Freour, Sylvain, and Jacquemin, Frederic
- Published
- 2019
4. On the identification of the coefficient of moisture expansion of polyamide-6: Accounting differential swelling strains and plasticization
- Author
-
Obeid, Hassan, Clément, Alexandre, Fréour, Sylvain, Jacquemin, Frédéric, and Casari, Pascal
- Published
- 2018
- Full Text
- View/download PDF
5. In situ neutron measurements and modelling of the intergranular strains in the near-β titanium alloy Ti-β21S
- Author
-
Hounkpati, Viwanou, Fréour, Sylvain, Gloaguen, David, Legrand, Vincent, Kelleher, Joe, Kockelmann, Winfried, and Kabra, Saurabh
- Published
- 2016
- Full Text
- View/download PDF
6. Qualitative and quantitative assessment of water sorption in natural fibres using ATR-FTIR spectroscopy
- Author
-
Célino, Amandine, Gonçalves, Olivier, Jacquemin, Frédéric, and Fréour, Sylvain
- Published
- 2014
- Full Text
- View/download PDF
7. Nouvelle méthode de maintenance CBM pour améliorer la durée de vie des pales d’éoliennes implantées dans les zones arides
- Author
-
Rezig Ahmida, Yousfi Ahmed, Fréour Sylvain, Jacquemin Frédéric, and Branchu Samuel
- Subjects
Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
l’amélioration de la durée de vie des pales éoliennes opérant dans une région aride au-delà de sa durée de vie habituelle de 20 ou 25 ans oblige leur propriétaire à augmenter le nombre des inspections dans le cadre de la maintenance préventive sachant que les coûts de maintenance et d’arrêt d’une d’éolienne ont un impact direct sur la production totale et peuvent représenter jusqu’à 25% de l’énergie produite. Sachant que dans une région poussiéreuse, les pales sont soumises à une usure érosive qui contribue à la modification de la forme aérodynamique du bord d’attaque et réduit ainsi les performances de l’éolienne. Ce papier décrive et propose une nouvelle méthode de maintenance CBM pour améliorer la durée de vie d’une pale éolienne. Les résultats expérimentaux montrent que l’utilisation de cette méthode est très efficace pour détecter toute dégradation provoquée par l’usure érosive à la surface d’une pale pendant son service.
- Published
- 2019
- Full Text
- View/download PDF
8. Effet de l’érosion par des particules de sable sur la performance des pales d’éoliennes dans les zones arides et semi-arides
- Author
-
Rezig Ahmida, Yousfi Ahmed, Fréour Sylvain, and Jacquemin Frédéric
- Subjects
Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Cet article présente les résultats d’une recherche expérimentale visant à étudier la dégradation de la surface des pales d’éoliennes situées dans des zones arides causée par les impacts de particules de sable et l’influence qui en résulte sur leur performance énergétique. Les essais sont effectués dans une sableuse à érosion puis dans la soufflerie pour la pale en fibre de verre / polyester non revêtue sous différents angles et durées d’impact. Les forces aérodynamiques sur les profiles NACA 4412 sont déterminées expérimentalement. Tous les profiles (AR = 0,571) sont testés dans une soufflerie à une vitesse de l’air de 10 m/s au nombre de Reynolds 6.5×105. Les résultats montrent les différences de comportement détectées pour les échantillons avec T = 160s, T = 240s et T = 340s (quand Ra augmente) en les comparant avec l’échantillon lisse (T = 0s, Ra = 0,94). Les coefficients de force (CL et CD) montrent des changements significatifs qui conduisent à une diminution du rapport portance-traînée et donc une perte de performance notable.
- Published
- 2019
- Full Text
- View/download PDF
9. Influence of morphologic texture on stress analysis by X-ray and neutron diffraction in single-phase metallic materials
- Author
-
Hounkpati, Viwanou, Fréour, Sylvain, Gloaguen, David, and Legrand, Vincent
- Published
- 2014
- Full Text
- View/download PDF
10. Influence of the mechanical and geometrical parameters on the cellular uptake of nanoparticles: A stochastic approach.
- Author
-
Iaquinta, Sarah, Khazaie, Shahram, Ishow, Éléna, Blanquart, Christophe, Fréour, Sylvain, and Jacquemin, Frédéric
- Subjects
NANOPARTICLES ,CANCER treatment ,MATHEMATICAL models ,DRUG utilization ,SENSITIVITY analysis - Abstract
Nanoparticles (NPs) are used for drug delivery with enhanced selectivity and reduced side‐effect toxicity in cancer treatments. Based on the literature, the influence of the NPs mechanical and geometrical properties on their cellular uptake has been studied through experimental investigations. However, due to the difficulty to vary the parameters independently in such a complex system, it remains hard to efficiently conclude on the influence of each one of them on the cellular internalization of a NP. In this context, different mechanical / mathematical models for the cellular uptake of NPs have been developed. In this paper, we numerically investigate the influence of the NP's aspect ratio, the membrane tension and the cell‐NP adhesion on the uptake of the NP using the model introduced in1 coupled with a numerical stochastic scheme to measure the weight of each one of the aforementioned parameters. The results reveal that the aspect ratio of the particle is the most influential parameter on the wrapping of the particle by the cell membrane. Then the adhesion contributes twice as much as the membrane tension. Our numerical results match the previous experimental observations. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
11. On the use of the geometric mean approximation in estimating the effective hygro-elastic behavior of fiber-reinforced composites
- Author
-
Fréour, Sylvain, Jacquemin, Frederic, and Guillén, Ronald
- Published
- 2007
- Full Text
- View/download PDF
12. Dimensional variation and evolution of mechanical properties of wet aged composites reinforced with flax fibers.
- Author
-
Hachem, Ziad El, Célino, Amandine, Challita, Georges, Branchu, Samuel, Duigou, Antoine Le, and Fréour, Sylvain
- Subjects
FIBROUS composites ,MATERIALS testing ,NATURAL fibers ,MECHANICAL behavior of materials - Abstract
The aim of this study is to investigate the dimensional variation of polypropylene composites reinforced with UD flax fibers, and the modification of its dynamical mechanical properties after moisture absorption. The effects of fiber content, coupling agent and moisture content were also examined. Results have shown that the swelling increases significantly when increasing the fiber content and the moisture content. It was also concluded that the addition of a coupling agent reduces the swelling of the composite, by improving the adhesion at the fiber/matrix interface. It is interesting to note that the coefficient of hygroscopic swelling of the composites presents a non-linear evolution, with respect to moisture content. Moreover, it was proved that the addition of fiber and the presence of a coupling agent improve the dynamical mechanical properties of the material. However, following moisture absorption, the storage modulus seems to be decreasing, which might be due to the micro-cracks created as a result of the internal swelling of fibers. Additionally, the coupling agent was found to increase the storage modulus of the composite at dry state, whereas following moisture absorption, it was found that the coupling agent does not modify the storage modulus of the material. Moreover, the results reveal that the dynamic mechanical properties of the composites are hardly dependent on the quality of the material, such as the state of the adhesion at the fiber/matrix interface, a possible misalignment of the fibers within the material and the moisture content within the material at the testing time. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
13. Numerical modeling of the hygro-mechanical behavior of the 3D composite materials.
- Author
-
Mbacké, Mamadou Abdoul, Khazaie, Shahram, Fréour, Sylvain, and Jacquemin, Frédéric
- Subjects
COMPOSITE materials ,HUMAN behavior models ,BEHAVIORAL assessment ,STRENGTH of materials ,ULTIMATE strength ,ELASTIC constants - Abstract
The composite materials used in marine environments are subjected to mechanical loads along with the water absorption. The analysis of the behavior of such materials requires to take into account the coupling between the mechanical and diffusion behaviors. The hygro-mechanical coupling has been widely investigated experimentally and numerically. This paper presents a numerical approach to model the hygro-mechanical coupling of composite materials. The diffusion process is modeled via the classical Fick's law. The elasticity matrix is considered to belong to transverse isotropic class, i.e. the composite studied is a unidirectional one. The components of the former are considered as moisture content dependent. The constitutive law takes into account on the one hand the strain induced by the hygroscopic swelling and on the other hand the dependence of the mechanical properties (elastic constants along with the material ultimate strengths) on the moisture content. These are implemented in a finite element software used to investigate the influence of the hygro-mechanical coupling on the composite material behavior. The robustness of our numerical tool is investigated with some numerical case studies. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
14. Durability of Composite Materials under Severe Temperature Conditions: Influence of Moisture Content and Prediction of Thermo-Mechanical Properties During a Fire.
- Author
-
Costa, Juan Pablo Márquez, Legrand, Vincent, and Fréour, Sylvain
- Subjects
COMPOSITE materials ,HIGH temperatures ,MECHANICAL models ,LAMINATED materials ,PREDICTION models - Abstract
The main objective of the present study was to develop a fire thermal model able to predict the evolution of the temperature and decomposition gradient across a laminated composite structure when exposed to fire. The thermal response of composite laminate made of organic polymer matrix was investigated under severe temperature conditions as samples were exposed to high temperatures up to 750 °C. The highlight is that a behavior law for water is included in our thermo-mechanical model to estimate effects due to a moisture content field on the thermal response of composite laminates. In particular, porosity and gas pressure are strongly influenced by the presence of water in the material and modify the thermal behavior accordingly. This enabled us to propose a new approach that can be used for the prediction of hygro-thermo-chemico-mechanical post-combustion properties in a very large number of material and fire scenarios. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
15. What about the relevance of the diffusion parameters identified in the case of incomplete Fickian and non-Fickian kinetics?
- Author
-
Cocaud, Julie, Célino, Amandine, Fréour, Sylvain, and Jacquemin, Frédéric
- Subjects
COMPOSITE materials ,DIFFUSION kinetics ,LEAST squares ,ELASTICITY ,STRAINS & stresses (Mechanics) ,MECHANICAL behavior of materials - Abstract
The aim of this work is to study the relevance of the diffusion parameters identified on kinetics whose saturation levels are unknown. Two types of diffusion kinetics have been considered: a Fickian and a non-Fickian kinetics. Numerical experiments, based on the generation of noisy data corresponding to reference values of diffusion parameters, have been carried out. The two models used in this study are Fick's model and the «Dual-Fick» model. Identification procedures were then applied on these data sets, truncated at different critical times. In the specific case of Dual Fick kinetics, the classical least square method was compared to an alternative approach based on the piecewise analysis of the shape of the diffusion curves. The identified parameters may deviate significantly from the expected reference values when the truncation threshold of the data set precedes the steady state. Also, these inaccurate parameters impact the predictions of global water uptake, water concentration profiles and stresses gradients through the thickness of the sample. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
16. Accounting for differential swelling in the multi-physics modelling of the diffusive behaviour of polymers
- Author
-
Sar, Bun Eang, Fréour, Sylvain, Davies, Peter, Jacquemin, Frédéric, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
- Subjects
Hygromechanical equation ,unsymmetrical loading of moisture ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,moisture absorption ,thermodynamical approach ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience; The purpose of this paper is to take into account the deri vative by moisture content of polymer volume in order to establish a diffusion law within the so-called “thermodynamical approach” for a polymer material which experiences a hygro-mechanical load. In this study, the specific case corresponding to the existence of unsymmetrical hygroscopic boundary conditions was inv estigated.
- Published
- 2014
17. Qualitative and quantitative assessment of water sorption in natural fibers using FTIR spectroscopy
- Author
-
Célino, Amandine, Gonçalves, Olivier, Fréour, Sylvain, Jacquemin, Frédéric, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,ComputingMilieux_MISCELLANEOUS ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
National audience
- Published
- 2013
18. Accounting the differential swelling in multiphysics moisture diffusion models
- Author
-
Jacquemin, Frédéric, Sar, Bun Eang, Fréour, Sylvain, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Published
- 2013
19. A multi-scale analysis of local stresses during the cure of a composite tooling material
- Author
-
Lacoste, Emmanuel, Szymanska, K., Terekhina, S., Fréour, Sylvain, Jacquemin, Frédéric, Salvia, M., État Mécanique et Microstructure des Matériaux (E3M), Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), and Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Cure process ,Composite material ,Multiscale ,[SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph] ,Residual stress ,Thermoset polymer - Abstract
International audience; This paper is dedicated to the cure of an in-plane isotropic carbon-epoxy tooling material presenting a specific mesostructure. Eshelby-Kroner self-consistent model (EKSC) is used to achieve a two-steps scale transition procedure, allowing relating microscopic to macroscopic properties of the material, and estimating its multi-scale mechanical states. This procedure is used to predict the local residual stresses due to thermal and chemical shrinkage of the resin, depending on the manufacturing process conditions. An experimental investigation provides the BMI resin cure kinetics and mechanical properties as a function of the temperature and conversion degree. The consequences of these evolutions on the local mechanical states are investigated and discussed.
- Published
- 2013
20. A comparison between the free volume theory and the thermodynamical approach for modelling of the multiscale interaction between stress and moisture diffusion in composite materials
- Author
-
Jacquemin, Frédéric, Sar, Bun Eang, Fréour, Sylvain, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Published
- 2012
21. On the relevance of the Kröner-Eshelby scale transition model for multi-morphous composite materials
- Author
-
Lacoste, Emmanuel, Fréour, Sylvain, Jacquemin, Frédéric, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Published
- 2009
22. Multi-scale analysis of fiber reinforced composite parts submitted to environmental and mechanical loads
- Author
-
Jacquemin, Frédéric, Fréour, Sylvain, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
homogenization ,identification ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,polymer-matrix composites ,scale transition modelling - Abstract
The purpose of this work is to present various application of statistical scale transition models to the analysis of polymer-matrix composites submitted to thermo-hygro-mechanical loads. In order to achieve such a goal, two approaches, classically used in the field of modelling heterogeneous material are studied: Eshelby-Kröner self-consistent model on the one hand and Mori-Tanaka approximate, on the second hand. Both models manage to handle the question of the homogenization of the microscopic properties of the constituents (matrix and reinforcements) in order to express the effective macroscopic coefficients of moisture expansion, coefficients of thermal expansion and elastic stiffness of a uni-directionally reinforced single ply. Inversion scale transition relations are provided also, in order to identify the effective unknown behaviour of a constituent. The proposed method entails to inverse scale transition models usually employed in order to predict the homogenised macroscopic elastic/hygroscopic/thermal properties of the composite ply from those of the constituents. The identification procedure involves the coupling of the inverse scale transition models to macroscopic input data obtained through either experiments or in the already published literature. Applications of the proposed approach to practical cases are provided: in particular, a very satisfactory agreement between the fitted elastic constants and the corresponding properties expected in practice for the reinforcing fiber of typical composite plies is achieved. Another part of this work is devoted to the extensive analysis of macroscopic mechanical states concentration within the constituents of the plies of a composite structure submitted to thermo-hygro-elastic loads. Both numerical and a fully explicit version of Eshelby-Kröner model are detailed. The two approaches are applied in the viewpoint of predicting the mechanical states in both the fiber and the matrix of composites structures submitted to a transient hygro-elastic load. For this purpose, rigorous continuum mechanics formalisms are used for the determination of the required time and space dependent macroscopic stresses. The reliability of the new analytical approach is checked through a comparison between the local stress states calculated in both the resin and fiber according to the new closed form solutions and the equivalent numerical model: a very good agreement between the two models was obtained. The purpose of the final part of this work consists in the determination of microscopic (local) quadratic failure criterion (in stress space) in the matrix of a composite structure submitted to purely mechanical load. The local failure criterion of the pure matrix is deduced from the macroscopic strength of the composite ply (available from experiments), using an appropriate inverse model involving the explicit scale transition relations previously obtained for the macroscopic stress concentration at microscopic level. Convenient analytical forms are provided as often as possible, else procedures required to achieve numerical calculations are extensively explained. Applications of this model are achieved for two typical carbon-fiber reinforced epoxies: the previously unknown microscopic strength coefficients and ultimate strength of the considered epoxies are identified and compared to typical expected values published in the literature.
- Published
- 2009
23. Multi-scale coupling between internal stresses and moisture diffusion
- Author
-
Youssef, Georges, Jacquemin, Frédéric, Fréour, Sylvain, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Published
- 2009
24. Homogenization of Moisture Diffusing Behavior of Composite Materials with Impermeable or Permeable Fibers: Application to Porous Composite Materials
- Author
-
Gueribiz, Djelloul, Rahmani, M., Jacquemin, Frédéric, Fréour, Sylvain, Guillen, Ronald, Loucif, K., Université Amar Telidji - Laghouat, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), and Université Ferhat-Abbas Sétif 1 [Sétif] (UFAS1)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience; In order to predict the long-term durability of polymer matrix composite materials submitted to humid environments, the moisture diffusion behavior has to be investigated. The knowledge of the effective diffusivity is actually required, for estimating the moisture content of polymer-based fiber-reinforced materials, even when a basic behavior such as Fick's law is assumed to occur. The original contribution of the present work is to provide new analytical solutions for the effective diffusivities from the solving of unit cell problems on representative volume elements by means of several multi-scale approaches. Composite materials with impermeable or permeable fibers are extensively investigated. The proposed approaches are extended to the practical case of composite materials containing realistic voids volume fractions.
- Published
- 2009
25. A study of the mechanical behavior of thermo-oxidized composite lamina
- Author
-
Yousfi, A., Fréour, Sylvain, Jacquemin, Frédéric, Rhamani, M., Osmani, M., Guillen, Ronald, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Department of Mechanical Engineering, and University Amar Tilidji
- Subjects
[SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph] ,Local stress ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,Polymer matrix composites ,Scale transition models ,Thermo-oxidation ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience; The aim of this work is the study of the mechanical behavior of polymer matrix composites reinforced with carbon fiber, which have undergone a thermo-oxidation process. The purpose of this work is the multi-scale analysis of the consequences of oxidation of epoxy matrices on the intrinsic mechanical properties of the external composite ply, on the one hand, and on the internal mechanical states experienced by the structure as a function of the considered mechanical load, on the other hand. Effective mechanical properties of oxidized composite plies are determined according to Eshelby-Kröner self-consistent homogenization procedure, depending on the progress of the oxidation process. The results are compared to the corresponding properties estimated by the finite element method. The macroscopic mechanical states are calculated for T300/5208 unidirectional composite and laminates. The macroscopic stresses undergone by each ply of the structure was deduced from the classical lamination theory and by the finite element method, whereas the local stresses in both constituents (carbon fiber and epoxy matrix) were calculated for each ply of structure, through an analytical stress concentration relation previously demonstrated in [1], which satisfies the mathematical framework of Eshelby-Kröner self-consistent model. The local stresses have also been compared with the results obtained using the finite element method: the two approaches predict close together results.; L’objectif de ce travail est l’étude du comportement mécanique des composites à matrice polymère renforcée avec la fibre de carbone, qui ont subi un processus de thermo-oxydation. Le but de ce travail est l’analyse multi-échelle des conséquences de l’oxydation de la matrice époxy sur les propriétés mécaniques intrinsèques de la couche extérieure en composite, d’une part, et sur la mécanique interne des états, par la structure en fonction de la charge mécanique considéré, d’autre part. Les propriétés mécaniques effectives du composite oxydé plies sont déterminées en fonction de la procédure d’homogénéisation de Eshelby-Kröner auto-cohérent, et en fonction de l’avancement du processus d’oxydation. Les résultats sont comparés aux propriétés correspondantes estimées par la méthode des éléments finis. Les mécaniques macroscopiques sont calculées pour les états T300/5208 composites unidirectionnels et stratifiés. Le stress subi par macroscopique de chaque pli de la structure a été déduite de la théorie classique de laminage et par la méthode des éléments finis, alors que comme il le souligne à la fois, les constituants (fibre de carbone et de résine époxy matrice) ont été calculées pour chaque pli de la structure, par le biais d’une analyse du stress concentration, relation déjà démontrée dans [1], qui répond aux mathématiques qu’au modèle auto-cohérent de Eshelby-Kröner modèle auto-cohérent. Les stress locaux ont également été comparés avec les résultats obtenus en utilisant la méthode des éléments finis: les deux approchesprédisent des résultats proches.
- Published
- 2008
26. Effects of moisture dependent constituents properties on the hygroscopic stresses experienced by composites structures
- Author
-
Youssef, Georges, Fréour, Sylvain, Jacquemin, Frédéric, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
softening ,composite laminates ,modeling ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,hygroscopic stresses ,moisture diffusion ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience; The effects related to the evolution of the moisture-dependent hygroelastic properties of composite plies constituting a fiber-reinforced epoxy laminate on the predicted stress states in the structure during the transient stage of hygroscopic loading are investigated. The approach proposed involves the coupling of the classical continuum mechanics formalism to the Eshelby-Kroner self-consistent scale transition model. An inverse scale transition model is used to describe the evolution of local hygroelastic properties of the epoxy matrix as the process of moisture diffusion proceeds. The scale transition relations allow one to determine the local distribution of stresses in the constituents (fiber and matrix) of each ply of the laminates considered from the distribution of macroscopic stresses. Numerical simulations show that the account (or not) of softening of the composite structure under hygroscopic loadings significantly affects the multiscale stress states predicted.
- Published
- 2008
27. Concentric cylinder model for predicting transient hygro-elastic stress concentration
- Author
-
Jacquemin, Frédéric, Fréour, Sylvain, Guillen, Ronald, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Published
- 2006
28. Analytical Modeling of Transient Hygro-elastic Stress Concentration: Application to embedded optical fiber in a non-uniform transient strain field
- Author
-
Jacquemin, Frédéric, Fréour, Sylvain, Guillén, Ronald, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Fibers ,Hygrothermal effects ,Stress concentration ,Residual stress ,Layered structures ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience; The aim of this work is to propose an analytical model for transient hygro-elastic stresses in transversely isotropic multi-layered cylinders. This approach allows one to calculate the time and space dependent hygro-elastic stresses in fiber-reinforced composite submitted to hygroscopic fields by applying the classical continuum mechanics formalism. Application of the proposed model to the case of an embedded optical fiber shows interesting results, concerning the stress field perturbation occurring in the composite in the vicinity of the intrusive optical fiber. The model proposed in this study provides a detailed stress analysis of the inclusion which is required to correctly interpret the data collected through the optical fiber and deduce stresses experienced by the host material.
- Published
- 2006
29. Estimation of Ti-17 beta-phase Single-Crystal Elasticity Constants using X-Ray Diffraction measurements and inverse scale transition modelling
- Author
-
Fréour, Sylvain, Gloaguen, David, François, Marc, Perronnet, Annick, Guillen, Ronald, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,ComputingMilieux_MISCELLANEOUS ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience
- Published
- 2005
30. A self-consistent approach for transient hygroscopic stresses and moisture expansion coefficients of fiber-reinforced composites
- Author
-
Jacquemin, Frédéric, Fréour, Sylvain, Guillén, Ronald, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
Stress analyses are performed in unidirectional fiber-reinforced composites, exposed to ambient fluid, byextending a classical self-consistent model to hygro-elastic solicitations. Constitutive laws are given for themacroscopic elastic properties and Coefficients of Moisture Expansion (CME) by considering a jump inmoisture content between the fiber and the matrix. The macroscopic (ply) and local (fiber and matrix) internalstress states are evaluated for various moisture content ratios between the matrix and the ply. The macroscopicstresses are calculated by using continuum mechanics formalisms and the local stresses are deduced from thescale transition model
- Published
- 2004
31. Prediction of residual stresses in two-phases materials: comparison between simplified models and experimental results
- Author
-
Fréour, Sylvain, Gloaguen, David, François, Manuel, Guillen, Ronald, Laboratoire d'Applications des Matériaux à la Mécanique, Laboratoire des Systèmes Mécaniques et d'Ingénierie Simultanée (LASMIS), Institut Charles Delaunay (ICD), and Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
contraintes résiduelles ,residual stresses ,matériaux biphasés ,two-phases materials ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,scale transition models ,modèles de transition d’échelle ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience; This article deals with the prediction of residual stresses due to plastic solicitations in twophases materials. Reliability of simplified models is evaluated by a comparison between calculations and measurements realized on plastically pre-strained perlitic steels. Two kinds of models are investigated: the classical predictive method and inverse approaches. A semiempiric model based on Dvorak and Benveniste formalism is proposed in order to solve the problem of the excessively high stiffness predicted by the classical models. This method improves results obtained by the others studied approaches and achieves to reproduce curves of residual stresses in each phase and macroscopic stress-strain response, for a single set of hardening parameters.; Cet article apporte une contribution à la prévision des contraintes résiduelles d'origine plastique dans les matériaux biphasés. Les performances de modèles simplifiés sont évaluées par une confrontation avec des mesures réalisées sur des aciers perlitiques prédéformés. Deux manières de piloter les modèles sont envisagées : la méthode prédictive classique et une approche inverse. Devant le constat de la trop grande raideur des modèles, une approche semi-empirique, basée sur le modèle de Dvorak et Benveniste, est proposée. Cette méthode franchit les verrous des formalismes classiques en parvenant à reproduire pour un seul jeu de paramètres d'écrouissage, les courbes de contraintes résiduelles de chacune des phases ainsi que celle correspondant au chargement imposé au polycristal biphasé.
- Published
- 2004
32. Thermal properties of polycrystals
- Author
-
Fréour, Sylvain, Gloaguen, David, Francois, Manuel, Guillén, Ronald, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Systèmes Mécaniques et d'Ingénierie Simultanée (LASMIS), Institut Charles Delaunay (ICD), and Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MAT]Engineering Sciences [physics]/Materials - Abstract
International audience; The development of thermal residual stresses was investigated in polycrystalline materials. Two complementary ways were used: the experimental values obtained by X-ray diffraction were compared to the results predicted by self-consistent scale transition approaches. First, single-phase materials were considered. The model was checked through the experimental study of rolled textured polycrystalline α-Zr and α-Ti with hexagonal closed packed structure. The level and the influence of the thermal stresses on the macroscopic behaviour have been quantified. In a second part, the model was extended to the case of two-phase materials. A new approach was developed in order to characterize the coefficient of thermal expansion (CTE) of phases embedded in multiphase materials. The analysis of the problem was based on the coupling of numerical simulations with thermo-elastic scale transition models and experiments. The whole approach was finally checked through the study of an Al-50%vol.-SiC-50%vol. MMC. The CTE of Silicon Carbide were determined as a function of the temperature. Simulated results obtained show a very good agreement with experimental values available in the literature.
- Published
- 2003
33. Characterization and modeling of the moisture diffusion behavior of natural fibers.
- Author
-
Célino, Amandine, Fréour, Sylvain, Jacquemin, Frédéric, and Casari, Pascal
- Subjects
FIBERS ,DIFFUSION ,POLYMERIC composites ,HYGROTHERMOELASTICITY ,POLYMER structure ,THERMAL properties of polymers - Abstract
Natural fibers have good properties to be used as reinforcement in composite materials. The main issue is their hydrophilic behavior. So we propose here to investigate the diffusion phenomenon in such fibres. First, a brief characterization of four vegetal fibers has been achieved. We show that all fibers have a similar composition and structure despite their different origin. Then, their moisture diffusive behavior was investigated. The samples were submitted to hygro-thermal aging either in total water immersion at room temperature or in an environmental chamber at 80% relative humidity and 23°C. Various predictive models were used to simulate experimental curves. Results show that all fibers exhibit a similar diffusive behavior in a same environment. In immersion, specimens show anomalous absorption kinetics and Langmuir theory actually describes very well the diffusion kinetics in such conditions, whereas the same fibers follow a Fickian diffusion when they are exposed to vapor during relative humidity aging. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
34. Identification of moisture diffusion parameters in organic matrix composites.
- Author
-
Dana, Hossein Ramezani, Perronnet, Annick, Fréour, Sylvain, Casari, Pascal, and Jacquemin, Frédéric
- Subjects
MOISTURE ,DIFFUSION ,PARAMETERS (Statistics) ,GLASS fiber sculpture ,POLYMERS - Abstract
In this work, moisture penetration in glass fiber-reinforced polymers was systematically investigated through both experiments and theoretical approaches. The diffusivities of the neat resin and those of unidirectional composite plates containing various glass fiber volume fractions have been identified through the analysis of hygro-thermal aging tests. The main aim of the present paper consists in comparing the evolutions, as a function of the fiber volume fractions, of the moisture diffusion coefficients deduced from experiments to the corresponding values, predicted by the many traditional scale transition relations available in the literature. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
35. Towards the Prediction of Sandwich Composites Durability in Severe Condition of Temperature: A New Numerical Model Describing the Influence of Material Water Content during a Fire Scenario.
- Author
-
Márquez Costa, Juan Pablo, Legrand, Vincent, Fréour, Sylvain, and Jacquemin, Frédéric
- Subjects
FORECASTING ,SANDWICH construction (Materials) ,COMPOSITE structures ,THERMAL expansion ,GEOTHERMAL resources ,VINYL ester resins - Abstract
An advanced fire thermal model was developed to predict the evolution of the temperature and decomposition gradient across a sandwich composite structure when exposed to high temperatures (fire). This model allows the prediction of a large numbers of parameters, such as thermal expansion, gas mass storage, porosity, permeability, density, and internal pressure. The highlight of this model is that we consider, in the sandwich constituents (core and skins), additional parameters, such as changing volume porosities, other coupled constituents (as infused resin in the balsa core), and what make the main originality of the present approach: moisture content (free and bounded water). The time dependence of many parameters, i.e., among others, the combustion advancing front and mechanical properties, can be predicted in a large number of material and fire scenarios. The proposed approach was validated in the case of sandwich panels, with glass/polyester or glass/vinyl ester skins and balsa core, exposed to high temperatures up to 750 °C. The influence of water on the thermal and mechanical responses is also highlighted. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
36. Hygroscopic multi-scale behavior of polypropylene matrix reinforced with flax fibers.
- Author
-
El Hachem, Ziad, Célino, Amandine, Challita, Georges, Moya, Marie-José, and Fréour, Sylvain
- Subjects
- *
NATURAL fibers , *FLAX , *POLYPROPYLENE , *MATRIX effect , *MALEIC anhydride , *FIBERS , *MOISTURE - Abstract
• Water diffusion rate is proportional to the fiber content for a constant relative humidity (RH) condition. • The addition of a coupling agent results in a lesser moisture absorption. • Moisture absorption capacity increases with the increase of the environmental RH, following a sigmoidal law. • The law of mixtures is not always applicable on bio-based composites exposed to high RH due to the containing effect of the surrounding matrix. Due to the hydrophilic behavior of natural fibers, bio-based composites made of vegetal fibers are still facing some obstacles that impair their large-scale development in the modern and promising industrial applications. Therefore, the aim of this study is to evaluate the multi-scale moisture absorption phenomena within a unidirectional bio-based composite material reinforced with flax fibers. The effect of fiber fraction, coupling agent and relative humidity on diffusion kinetics have been studied. In this work, composites are made of polypropylene matrix with various flax fiber contents, with the addition of maleic anhydride as a coupling agent. Samples were submitted to wet aging at 75% and 95% relative humidities (RH) under room temperature of 23 °C. Results have shown significant increase of moisture absorption with the increase of fiber content and relative humidity. In fact, the samples reinforced with 40% flax fiber content absorb as much as 9.15% moisture at saturation at 95% RH, whereas the samples reinforced with 20% flax fiber content only absorb 4.91% moisture at the same RH condition. However, with the addition of a coupling agent, composites undergo a decrease in moisture absorption due to an improved adhesion at the fiber/matrix interface. The moisture content of the samples reinforced with 40% flax fiber has indeed been reduced to 7.52% at 95% RH owing to the addition of the coupling agent. In this work, for the first time, the prediction of the maximum moisture absorption capacity of a bio-based composite has been studied, using a multiscale homogenization method. The obtained results highlight that once the fibers are incorporated within the matrix, the overall macroscopic property of the composite does not always satisfy the classical law of mixture, even for the maximum moisture absorption capacity. In fact, it has been concluded that the difference between the experimental results and those of the homogenization method is primarily due to a hygro-mechanical coupling, induced by the containment effect the matrix exerts on the fibers. This prediction strongly depends on the fiber content, the environmental relative humidity and the flax fiber sorption behavior which can vary from a fiber to another. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
37. The hygroscopic behavior of plant fibers: a review.
- Author
-
Célino A, Fréour S, Jacquemin F, and Casari P
- Abstract
Environmental concern has resulted in a renewed interest in bio-based materials. Among them, plant fibers are perceived as an environmentally friendly substitute to glass fibers for the reinforcement of composites, particularly in automotive engineering. Due to their wide availability, low cost, low density, high-specific mechanical properties, and eco-friendly image, they are increasingly being employed as reinforcements in polymer matrix composites. Indeed, their complex microstructure as a composite material makes plant fiber a really interesting and challenging subject to study. Research subjects about such fibers are abundant because there are always some issues to prevent their use at large scale (poor adhesion, variability, low thermal resistance, hydrophilic behavior). The choice of natural fibers rather than glass fibers as filler yields a change of the final properties of the composite. One of the most relevant differences between the two kinds of fiber is their response to humidity. Actually, glass fibers are considered as hydrophobic whereas plant fibers have a pronounced hydrophilic behavior. Composite materials are often submitted to variable climatic conditions during their lifetime, including unsteady hygroscopic conditions. However, in humid conditions, strong hydrophilic behavior of such reinforcing fibers leads to high level of moisture absorption in wet environments. This results in the structural modification of the fibers and an evolution of their mechanical properties together with the composites in which they are fitted in. Thereby, the understanding of these moisture absorption mechanisms as well as the influence of water on the final properties of these fibers and their composites is of great interest to get a better control of such new biomaterials. This is the topic of this review paper.
- Published
- 2014
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.