https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sun, 15 Mar 2026 05:21:44 GMT 2026-03-15T05:21:44Z http://hdl.handle.net/10985/11135 Damage and permeability of composite laminates LAEUFFER, Hortense; BOIS, Christophe; WAHL, Jean-Christophe; LAVELLE, Florian; PERRY, Nicolas This study focuses on the link between damage development and permeability evolution of composite laminates. By making use of an original device, measurement of the permeability of composite pipes under pressure and quantification of leak paths were conducted. Presented results show that very few (about one per 100 cm2) leak paths are sufficient to increase the permeability of several orders of magnitude, suggesting the existence of a preliminary phase characterized by a progressive development of a few cracks. Damage modelling and identification are proposed, allowing this phase to be taken into account. From this modelling coupled with a simplified representation of the crack network, prediction of leak path density is provided. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/11135 2015-01-01T00:00:00Z LAEUFFER, Hortense BOIS, Christophe WAHL, Jean-Christophe LAVELLE, Florian PERRY, Nicolas This study focuses on the link between damage development and permeability evolution of composite laminates. By making use of an original device, measurement of the permeability of composite pipes under pressure and quantification of leak paths were conducted. Presented results show that very few (about one per 100 cm2) leak paths are sufficient to increase the permeability of several orders of magnitude, suggesting the existence of a preliminary phase characterized by a progressive development of a few cracks. Damage modelling and identification are proposed, allowing this phase to be taken into account. From this modelling coupled with a simplified representation of the crack network, prediction of leak path density is provided. http://hdl.handle.net/10985/11665 A new device to measure permeability evolution under pressure loading: application to CFRP pipes LAEUFFER, Hortense; ARBAOUI, Jamal; BOIS, Christophe; LAVELLE, Florian; WAHL, Jean-Christophe; PERRY, Nicolas This paper presents an experimental setup for the measurement of permeability evolution induced by mechanical loading. The experiment consists in ressurizing a pipe-specimen. Internal pressure is used for both loading and permeability measurement. The external face of the pipe is accessible, so that leak paths can be localized and quantified. In order to avoid premature cracking of the specimen due to the device, sealing components were designed using Finite Element Analysis with respect to the stiffness of pipes to be tested. Although current design enables various carbon composite pipes to be tested, it can be easily adapted to other materials. A validation of the design was achieved by measuring permeability on an impermeable pipe. The experimental setup and method were applied to a composite filament wound pipe. Results give substantial quantitative information on the relationship between the number of leak paths and the increase in material permeability. Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10985/11665 2017-01-01T00:00:00Z LAEUFFER, Hortense ARBAOUI, Jamal BOIS, Christophe LAVELLE, Florian WAHL, Jean-Christophe PERRY, Nicolas This paper presents an experimental setup for the measurement of permeability evolution induced by mechanical loading. The experiment consists in ressurizing a pipe-specimen. Internal pressure is used for both loading and permeability measurement. The external face of the pipe is accessible, so that leak paths can be localized and quantified. In order to avoid premature cracking of the specimen due to the device, sealing components were designed using Finite Element Analysis with respect to the stiffness of pipes to be tested. Although current design enables various carbon composite pipes to be tested, it can be easily adapted to other materials. A validation of the design was achieved by measuring permeability on an impermeable pipe. The experimental setup and method were applied to a composite filament wound pipe. Results give substantial quantitative information on the relationship between the number of leak paths and the increase in material permeability. http://hdl.handle.net/10985/12834 Relationship between damage and permeability in liner-less composite tanks : experimental study at the lamina level LAEUFFER, Hortense; GUIOT, Brice; WAHL, Jean-Christophe; LAVELLE, Florian; BOIS, Christophe; PERRY, Nicolas The aim of this study is to provide a relevant description of damage growth and the resultant crack network to predict leaks in liner-less composite vessels. Tensile tests were carried out on three different laminates: [02/90n/02], [+45/-45]2s and [0/+67.5/-67.5]s. Number n varies from 1 to 3 in order to study the effect of ply thickness. Transverse crack and delamination at crack tips were identified with an optical microscope during tensile loading. A length of 100 mm was observed for several loading levels to evaluate statistical effects. Results highlight a preliminary step in the damage scenario with small crack densities before a second step where the crack growth speeds up. In bulk, cross-section examinations showed that no delamination occurred at crack tip in the material of the study (M21 T700). Cross-section examinations were also performed on [+45/-45]2s and [0/+67.5/-67.5]s layups in order to bypass the issue of free edge effects. Damage state in those layups was shown to be significantly different in the bulk than at the surface. Observations of the damage state in bulk for those layups demonstrated that there is no transverse crack in [+45/-45]2s specimens subjected to shear strains up to 4%, and that interactions between damage of consecutive plies strongly impact both the damage kinetics and the arrangement of cracks. These elements are fundamental for the assessment of permeability performance, and will be introduced in the predictive model. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/12834 2016-01-01T00:00:00Z LAEUFFER, Hortense GUIOT, Brice WAHL, Jean-Christophe LAVELLE, Florian BOIS, Christophe PERRY, Nicolas The aim of this study is to provide a relevant description of damage growth and the resultant crack network to predict leaks in liner-less composite vessels. Tensile tests were carried out on three different laminates: [02/90n/02], [+45/-45]2s and [0/+67.5/-67.5]s. Number n varies from 1 to 3 in order to study the effect of ply thickness. Transverse crack and delamination at crack tips were identified with an optical microscope during tensile loading. A length of 100 mm was observed for several loading levels to evaluate statistical effects. Results highlight a preliminary step in the damage scenario with small crack densities before a second step where the crack growth speeds up. In bulk, cross-section examinations showed that no delamination occurred at crack tip in the material of the study (M21 T700). Cross-section examinations were also performed on [+45/-45]2s and [0/+67.5/-67.5]s layups in order to bypass the issue of free edge effects. Damage state in those layups was shown to be significantly different in the bulk than at the surface. Observations of the damage state in bulk for those layups demonstrated that there is no transverse crack in [+45/-45]2s specimens subjected to shear strains up to 4%, and that interactions between damage of consecutive plies strongly impact both the damage kinetics and the arrangement of cracks. These elements are fundamental for the assessment of permeability performance, and will be introduced in the predictive model. http://hdl.handle.net/10985/12835 Caractérisation et prédiction du réseau de fissures dans les composites stratifiés - Application aux réservoirs de lanceurs spatiaux sans liner LAEUFFER, Hortense; WAHL, Jean-Christophe; BOIS, Christophe; PERRY, Nicolas La conception de réservoirs composites sans liner pour les lanceurs spatiaux nécessite d’étudier la relation endommagement perméabilité dans les stratifiés pour proposer des solutions répondant à la fois aux critères fonctionnels de résistance et de taux de fuite. Dans cet article des procédures expérimentales spécifiques s’appuyant sur des observations par microscopie optique et par microtomographie sous chargement de traction sont proposées pour caractériser les interactions et l’agencement entre les endommagements des différents plis en termes de seuil de fissuration, de longueur et de position relative des fissures mésoscopiques. Les résultats obtenus pour différents stratifiés carbone époxy mis en œuvre par placement de fibres automatisé sont présentés et des pistes de réflexion pour le développement d’un méso-modèle de prédiction des densités de points de fuite sont posées. Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10985/12835 2017-01-01T00:00:00Z LAEUFFER, Hortense WAHL, Jean-Christophe BOIS, Christophe PERRY, Nicolas La conception de réservoirs composites sans liner pour les lanceurs spatiaux nécessite d’étudier la relation endommagement perméabilité dans les stratifiés pour proposer des solutions répondant à la fois aux critères fonctionnels de résistance et de taux de fuite. Dans cet article des procédures expérimentales spécifiques s’appuyant sur des observations par microscopie optique et par microtomographie sous chargement de traction sont proposées pour caractériser les interactions et l’agencement entre les endommagements des différents plis en termes de seuil de fissuration, de longueur et de position relative des fissures mésoscopiques. Les résultats obtenus pour différents stratifiés carbone époxy mis en œuvre par placement de fibres automatisé sont présentés et des pistes de réflexion pour le développement d’un méso-modèle de prédiction des densités de points de fuite sont posées. http://hdl.handle.net/10985/11680 A model for the prediction of transverse crack and delamination density based on a strength and fracture mechanics probabilistic approach LAEUFFER, Hortense; GUIOT, Brice; WAHL, Jean-Christophe; LAVELLE, Florian; BOIS, Christophe; PERRY, Nicolas The aim of this study is to provide a relevant description of damage growth and the resultant network for leakage prediction in liner-less composite vessels. A damage meso-model built on strength and energy criteria as proposed in FFM (Finite Fracture Mechanics) is introduced. Both criteria have to be fulfilled for the creation of the first transverse crack of the RVE (Representative Volume Element). The increase of crack density and the propagation of micro-delamination at crack tips are managed by Fracture Mechanics using the energy release rate. In this way the effect of ply thickness is explicitly accounted. The energy release rate at the meso-scale (RVE scale) is calculated from a multiscale approach. Numerical results show that, in [0 2 /90 1 /0 2 ] and [0 2 /90 3 /0 2 ] lay-ups under tensile stress, no delamination should occur for values of the energy release rates from the literature. This conclusion is reinforced by cross-section examinations through the width of specimens submitted to tensile loading. Delamination almost disappears after removing a few microns of the surface. Experimental results also highlight a preliminary step in the damage scenario with small cracking rate, likely driven by weak areas (defects locations). The modelling of this step being fundamental for the prediction of first leak paths, it was introduced througha probabilistic approach. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/11680 2016-01-01T00:00:00Z LAEUFFER, Hortense GUIOT, Brice WAHL, Jean-Christophe LAVELLE, Florian BOIS, Christophe PERRY, Nicolas The aim of this study is to provide a relevant description of damage growth and the resultant network for leakage prediction in liner-less composite vessels. A damage meso-model built on strength and energy criteria as proposed in FFM (Finite Fracture Mechanics) is introduced. Both criteria have to be fulfilled for the creation of the first transverse crack of the RVE (Representative Volume Element). The increase of crack density and the propagation of micro-delamination at crack tips are managed by Fracture Mechanics using the energy release rate. In this way the effect of ply thickness is explicitly accounted. The energy release rate at the meso-scale (RVE scale) is calculated from a multiscale approach. Numerical results show that, in [0 2 /90 1 /0 2 ] and [0 2 /90 3 /0 2 ] lay-ups under tensile stress, no delamination should occur for values of the energy release rates from the literature. This conclusion is reinforced by cross-section examinations through the width of specimens submitted to tensile loading. Delamination almost disappears after removing a few microns of the surface. Experimental results also highlight a preliminary step in the damage scenario with small cracking rate, likely driven by weak areas (defects locations). The modelling of this step being fundamental for the prediction of first leak paths, it was introduced througha probabilistic approach.