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Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Analyse contrainte, Stress analysis, Análisis tensión, Etude théorique, Theoretical study, Estudio teórico, Matériau aiguilleté, Needled material, Material cosado, Matériau composite, Composite material, Material compuesto, Matériau fibre unidirectionnelle, Unidirectional fiber material, Material fibra unidireccional, Modélisation, Modeling, Modelización, Méthode élément fini, Finite element method, Método elemento finito, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété travers court, Through thickness property, Propiedad corta travesía, Résistance compression, Compressive strength, Resistencia compresión, Résistance traction, Tensile strength, Resistencia tracción, Simulation numérique, Numerical simulation, Simulación numérica, Stratifié, Laminate, Estratificado, Tissu textile, Woven material, Tela textil, A. Fabrics/textiles, A. Polymer-matrix composites (PMCs), C. Analysis, and D. Mechanical testing

A multiscale approach is used to predict transverse tensile and transverse compressive strength of unidirectional non-crimp fabric (NCF) composites. Numerical analysis on fibre/matrix scale is performed to obtain the transverse strength of the fibre bundle to be further used in an analytical mesoscale model to predict the strength of the unidirectional NCF composite. Design of unidirectional layer composites with the same fibres, interface, matrix and volume fractions as in the bundle is suggested as an alternative method for bundle strength determination. Good agreement of both methods for bundle transverse strength determination is demonstrated. The simple analytical model used on mesoscale gives accurate predictions of the tensile transverse strength whereas the compressive strength is underestimated. The necessity of including bundle waviness in models when bidirectional NCF composites are analysed is demonstrated by FEM stress analysis and by experimental data showing differences in transverse cracking pattern due to bundle waviness.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Epoxyde résine, Epoxy resin, Epóxido resina, Etude théorique, Theoretical study, Estudio teórico, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Matériau composite, Composite material, Material compuesto, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Mode rupture, Fracture mode, Modo ruptura, Modèle 3 dimensions, Three dimensional model, Modelo 3 dimensiones, Modèle statistique, Statistical model, Modelo estadístico, Modélisation, Modeling, Modelización, Mécanique rupture, Fracture mechanics, Mecánica ruptura, Méthode élément fini, Finite element method, Método elemento finito, Propagation fissure, Crack propagation, Propagación fisura, Propagation oblique, Oblique propagation, Propagación oblicua, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Simulation numérique, Numerical simulation, Simulación numérica, Stratifié, Laminate, Estratificado, Vérification expérimentale, Experimental test, Verificación experimental, Matériau fibre multidirectionnelle, Stratifié croisé, A. Polymer-matrix composites, B. Defects, C. Damage mechanics, and C. Statistical properties/methods

A previously developed statistical model for transverse cracking in cross ply laminates is extended to oblique cracking in multidirectional laminates. The oblique cracks are assumed to form in a ply when the local in-plane tensile stress normal to fibers exceeds the transverse strength of the ply. This strength is assumed to have a statistical distribution given by a two-parameter Weibull function. The model is applied to a glass-epoxy [0/602/0/-602]5 laminate in which cracking evolution of the four -60° plies in the middle of the laminate is examined. The local stress field in the cracked -60° plies is calculated by a three-dimensional finite element method based on a unit cell construction developed by Li et al. [1]. The measured crack density is found to agree well with that calculated by the statistical model.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Charge multiaxiale, Multiaxial load, Carga multiaxial, Diagramme SN, SN diagram, Diagrama SN, Endommagement, Damaging, Deterioración, Epoxyde résine, Epoxy resin, Epóxido resina, Essai fatigue, Fatigue test, Ensayo fatiga, Etude expérimentale, Experimental study, Estudio experimental, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Matériau composite, Composite material, Material compuesto, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Mode empilement, Stacking sequence, Modo apilamiento, Modèle mécanique, Mechanical model, Modelo mecánico, Modélisation, Modeling, Modelización, Mécanique rupture, Fracture mechanics, Mecánica ruptura, Propagation fissure, Crack propagation, Propagación fisura, Propriété mécanique, Mechanical properties, Propiedad mecánica, Résistance fatigue, Fatigue strength, Resistencia fatiga, Stratifié, Laminate, Estratificado, Tube, Tubo, Effet épaisseur, A. Laminates, B. Fatigue, C. Damage mechanics, and Multiaxial fatigue

In this work an experimental investigation on damage initiation and evolution in laminates under cyclic loading is presented. The stacking sequence [0/02/0/-02]s has been adopted in order to investigate the influence of the local multiaxial stress state in the off-axis plies and the possible effect of different thickness between the thin (2-plies) and the thick (4-plies) layers. Results are presented in terms of S-N curves for the initiation of the first cracks, crack density evolution, stiffness degradation and Paris-like curves for the crack propagation phase. The values of the off-axis angle 0 has been chosen in order to obtain local multiaxial stress states in the off-axis plies similar to those in previous studies for biaxially loaded tubes. Results concerning damage initiation and growth for these two specimen configurations are shown to be consistent for similar local multiaxial stress states.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Emission acoustique, Acoustic emission, Emisión acústica, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Fibre carbone, Carbon fiber, Fibra carbón, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Matériau composite, Composite material, Material compuesto, Matériau fibre unidirectionnelle, Unidirectional fiber material, Material fibra unidireccional, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Mode rupture, Fracture mode, Modo ruptura, Méthode mesure, Measurement method, Método medida, Méthode non destructive, Non destructive method, Método no destructivo, Orientation fibre, Fiber orientation, Orientación fibra, Propriété mécanique, Mechanical properties, Propiedad mecánica, Rupture fibre, Fibre fracture, Ruptura fibra, Résistance traction, Tensile strength, Resistencia tracción, Ténacité, Fracture toughness, Tenacidad, Uréthanne polymère, Polyurethane, Uretano polímero, A. Polymer-matrix composites (PMCs), B. Fatigue, D. Acoustic emission, D. Mechanical testing, and Thermosetting polyurethane

Acoustic emission analysis is used to investigate microscopic damage mechanisms and damage progress in unidirectional glass and carbon fibre reinforced composites. Under static loading the influence of fibre orientation on damage initiation and propagation is determined. A novel polyurethane matrix system significantly enhances material performance in terms of crack initiation load levels, crack growth, damage tolerance and off-axis tensile strength. Hysteresis measurements during stepwise increasing dynamic load tests highlight the effect of fibre-matrix-adhesion and resin fracture toughness in unidirectional 0° fibre reinforced composites. Acoustic detection of beginning fibre breakage correlates with a significant increase of loss work per cycle.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Défaut matériau, Material defect, Defecto material, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Matériau composite, Composite material, Material compuesto, Matériau fibre unidirectionnelle, Unidirectional fiber material, Material fibra unidireccional, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Méthode mesure, Measurement method, Método medida, Propriété mécanique, Mechanical properties, Propiedad mecánica, Préimprégné, Prepreg, Preimpregnado, Stratification, Estratificación, Stratifié, Laminate, Estratificado, Ténacité, Fracture toughness, Tenacidad, Insertion film intralaminaire, Ténacité intralaminaire, and Laminates

A novel initial crack insertion method, intralaminar film insertion method, was proposed to investigate the fracture toughness of unidirectional carbon fiber reinforced plastic (CFRP) laminates when the crack propagates inside the ply and not in the interlayer resin-rich area. Here, a release film was inserted inside a single lamina during the resin impregnation process of prepreg manufacturing. Mode I intralaminar fracture toughness tests were carried out for conventional CFRP laminates and interlayer toughened CFRP laminates. For comparison, two conventional methods were used to introduce initial cracks. One is the interlaminar film method, where a release film is inserted between two prepreg plies during the lay-up process. The other is the machined slit method, where a slit notch is machined in parallel to the layer of CFRP laminates. It was demonstrated that the proposed intralaminar film method can correctly evaluate the intralaminar fracture toughness of both conventional CFRP laminate and interlayer toughened CFRP laminate from the initial value to the propagation value. For this range, it was also found that the intralaminar fracture toughness of interlayer toughened CFRP laminate was the same as that of conventional CFRP laminate. Thus, the intralaminar fracture toughness was not influenced by interlayer toughening.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Batterie lithium, Lithium battery, Diffusion ion, Ion scattering, Difusión ión, Distribution concentration, Concentration distribution, Distribución concentración, Elasticité linéaire, Linear elasticity, Elasticidad lineal, Endommagement, Damaging, Deterioración, Etude théorique, Theoretical study, Estudio teórico, Exfoliation, Exfoliación, Fibre carbone, Carbon fiber, Fibra carbón, Fibre minérale, Mineral fiber, Fibra inorgánica, Ion lithium, Lithium ion, Litio ión, Matériau électrode, Electrode material, Material electrodo, Modélisation, Modeling, Modelización, Mécanique rupture, Fracture mechanics, Mecánica ruptura, Méthode élément fini, Finite element method, Método elemento finito, Propriété mécanique, Mechanical properties, Propiedad mecánica, Simulation numérique, Numerical simulation, Simulación numérica, A. Carbon fiber, and C. Finite element analysis (FEA)

Gradients in lithium ion concentration distribution in carbon fiber are accompanied by non-uniform fiber swelling leading to development of mechanical stresses. During lithium deintercalation these stresses may lead to initiation and growth of radial cracks in the fiber. The subsequent cycle of intercalation may result in arc-shaped cracks deviating from the tip of the radial cracks. These phenomena decrease the mechanical properties of fibers if used in structural batteries and reduce the charging properties of the battery by decreased diffusivity of lithium ions and by exfoliating layers on the fiber surface. The crack propagation and possible damage evolution scenarios are analyzed using linear elastic fracture mechanics. The crack geometry dependent ion concentration distributions and the elastic stress distributions were found using finite element software ANSYS.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Aptitude moulage, Mouldability, Moldeabilidad, Etude expérimentale, Experimental study, Estudio experimental, Fibre minérale, Mineral fiber, Fibra inorgánica, Formabilité, Formability, Formabilidad, Matériau aiguilleté, Needled material, Material cosado, Matériau composite, Composite material, Material compuesto, Matériau fibre tridirectionnelle, Tridirectional fiber material, Material fibra tridireccional, Ouvrabilité, Processability, Laborabilidad, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété technologique, Technological properties, Propiedad tecnológica, Rayon X, X ray, Rayos X, Renforcement mécanique, Strengthening, Refuerzo mecánico, Résistance cisaillement, Shear strength, Resistencia cizallamiento, Résistance compression, Compressive strength, Resistencia compresión, Stratifié, Laminate, Estratificado, Tissu textile, Woven material, Tela textil, Tissu verre, Glass fiber fabric, Tela vidrio, Tomographie numérique, Computerized tomography, A. 3-Dimensional reinforcement, A. Fabrics/textiles, A. Glass fibres, and D. Radiography

An investigation at the unit cell level of the sheared geometry of a single layer E-glass non-crimp 3D orthogonal woven reinforcement (commercialized under trademark 3WEAVE® by 3Tex Inc.) is performed by X-ray micro-computed tomography (micro-CT) observations. The aim is to observe, understand and quantify the effect of in-plane shear deformation on the composite reinforcement geometry, at mesoscale (i.e. unit cell level). It was observed that, increasing the shear deformation, Z-yarns maintain unchanged the distance between the yarns and as consequence the yarn cross-section has a reduced variation of width, mainly in the weft direction. Furthermore, the effect of the shear angle on the textile thickness during compression is measured, this being an important parameter after the forming and molding phases of a composite component production. Compression tests and micro-CT measurements of the thickness show similar values and are in agreement with the prediction obtained assuming the theoretical invariance of the volume in the considered range of shear deformations.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Critère rupture, Fracture criterion, Criterio ruptura, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Fibre carbone, Carbon fiber, Fibra carbón, Fibre minérale, Mineral fiber, Fibra inorgánica, Matériau composite, Composite material, Material compuesto, Matériau fibre unidirectionnelle, Unidirectional fiber material, Material fibra unidireccional, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Microfissuration, Microcracking, Microfisuración, Mode empilement, Stacking sequence, Modo apilamiento, Mode rupture, Fracture mode, Modo ruptura, Modèle mécanique, Mechanical model, Modelo mecánico, Modélisation, Modeling, Modelización, Méthode mesure, Measurement method, Método medida, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété travers court, Through thickness property, Propiedad corta travesía, Résistance traction, Tensile strength, Resistencia tracción, Epaisseur pli, B. Strength, B. Transverse cracking, C. Damage mechanics, and D. Optical microscopy

Failure of a ply due to transverse loading is one of the mechanisms that was taken into account in physically-based failure criteria, used in composites design. However, experimental data are scarce and the measurement techniques used in the past are time consuming and involve a lot of specimen handling during testing. While some physical information is currently well consolidated (such as the dependence of the strength on ply thickness, or in situ strength), there still remain relevant open questions. This work presents a methodology, which does not interfere with the tensile test, to detect transverse cracks by optical means. Four different configurations of CFRP are considered. The results show that the in situ strength depends on the thickness of the ply and the orientation of the adjacent layers. In the case of thick transverse plies, the strength is controlled by full-width transverse cracks whereas, in thin plies cracking parallel to the specimen's mid-plane occurs before transverse matrix cracking.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Compactage, Compaction, Compactación, Contrainte cisaillement, Shear stress, Tensión cizallamiento, Etude expérimentale, Experimental study, Estudio experimental, Fibre carbone, Carbon fiber, Fibra carbón, Fibre minérale, Mineral fiber, Fibra inorgánica, Fraction volumique, Volume fraction, Fracción volumétrica, Matériau aiguilleté, Needled material, Material cosado, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Modélisation, Modeling, Modelización, Moulage transfert, Transfer molding, Moldeo por transferencia, Perméabilité, Permeability, Permeabilidad, Polymère, Polymer, Polímero, Propriété transport, Transport properties, Propiedad transporte, Simulation numérique, Numerical simulation, Simulación numérica, Tissu textile, Woven material, Tela textil, Tissu carbone, A. Fabrics/textiles, E. Resin transfer moulding, and Shear deformation

This work presents the results of a study on the permeability and compaction behaviour of textiles under shear deformation. In this study a 0°/90° non-crimp carbon fibre fabric with an areal weight of 200 g/m2 is used. The influence of shear is observed under two conditions: constant cavity height and constant fibre volume fraction (Vf). Permeability measurements were conducted as one-dimensional as well as two-dimensional flow experiments, totalling 119 experiments. Additional compaction tests of the sheared textiles (13 experiments) lead to a more thorough understanding of the mechanisms at work. It is shown that for constant cavity heights the behaviour of the textile greatly changes between a shear angle of 15° and 20°. Up to an angle of 15° the permeability shows a linear increase for the principal axis and a linear decrease for the secondary axis. At shear angles above 20° the behaviour for both is non-linear. Furthermore this change of behaviour can also be observed in the rotation of the flow ellipse and the compaction measurements. Both show a double-linear development with a change of behaviour in the region of 15-20°.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Délaminage, Delamination, Delaminación, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Fibre carbone, Carbon fiber, Fibra carbón, Fibre minérale, Mineral fiber, Fibra inorgánica, Matériau composite, Composite material, Material compuesto, Matériau fibre unidirectionnelle, Unidirectional fiber material, Material fibra unidireccional, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Mesure acoustique, Acoustic measurement, Medida acústica, Modélisation, Modeling, Modelización, Méthode mesure, Measurement method, Método medida, Méthode non destructive, Non destructive method, Método no destructivo, Méthode ultrasonore, Ultrasonic method, Método ultrasonoro, Méthode élément fini, Finite element method, Método elemento finito, Stratifié, Laminate, Estratificado, A. Laminates, B. Delamination, D. Non-destructive testing, and Nonlinear acoustics

The paper presents an application of nonlinear acoustics for impact damage detection in composite laminates. Two composite plates were analysed. A low-velocity impact was used to damage one of the plates. Ultrasonic C-scan was applied to reveal the extent of barely visible impact damage. Finite element modelling was used to find vibration mode shapes of the plates and to estimate the local defect resonance frequency in the damaged plate. A delamination divergence study was performed to establish excitation parameters for nonlinear acoustics tests used for damage detection. Both composite plates were instrumented with surface-bonded, low-profile piezoceramic transducers that were used for the highfrequency ultrasonic excitation. Both an arbitrary frequency and a frequency corresponding to the local defect resonance were investigated. The low-frequency modal excitation was applied using an electromagnetic shaker. Scanning laser vibrometry was applied to acquire the vibro-acoustic responses from the plates. The study not only demonstrates that nonlinear vibro-acoustic modulations can successfully reveal the barely visible impact damage in composite plates, but also that the entire procedure can be enhanced when the ultrasonic excitation frequency corresponds to the resonant frequency of damage.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Concentration contrainte, Stress concentration, Concentración restringida, Endommagement, Damaging, Deterioración, Epoxyde résine, Epoxy resin, Epóxido resina, Etude théorique, Theoretical study, Estudio teórico, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Matériau composite, Composite material, Material compuesto, Matériau fibre unidirectionnelle, Unidirectional fiber material, Material fibra unidireccional, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Modèle mécanique, Mechanical model, Modelo mecánico, Modélisation, Modeling, Modelización, Mécanique milieu continu, Continuum mechanics, Mecánica medio contínuo, Mécanique rupture, Fracture mechanics, Mecánica ruptura, Orientation fibre, Fiber orientation, Orientación fibra, Plaque perforée, Perforated plate, Placa perforada, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Rupture fibre, Fibre fracture, Ruptura fibra, Résistance fatigue, Fatigue strength, Resistencia fatiga, Simulation numérique, Numerical simulation, Simulación numérica, Stratifié, Laminate, Estratificado, A. Laminates, B. Fatigue, B. Stress concentrations, and C. Damage mechanics

A model defined at the ply scale to predict the failure of laminated composites for static and fatigue loadings has been proposed. The model describes the loss of strength in the fibre direction for high levels of transverse damage. This phenomenon can be observed in a 0° tube by applying a cyclic torsion loading up to a high level of damage followed by a tensile test. The model includes an original approach based on a Fracture Characteristic Volume (FCV) to predict the fibre failure of laminated structures with stress concentrations. The FCV is a cylinder defined at the ply scale where the average stress is calculated and compared to the maximal strength of the material. The fibre failure model and an application to open hole plates loaded in fatigue are presented in this paper.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines classiques de la physique (y compris les applications), Fundamental areas of phenomenology (including applications), Mécanique des solides, Solid mechanics, Mécanique des structures et des milieux continus, Structural and continuum mechanics, Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Contrainte biaxiale, Biaxial stress, Tensión biaxial, Critère rupture, Fracture criterion, Criterio ruptura, Epoxyde résine, Epoxy resin, Epóxido resina, Etude théorique, Theoretical study, Estudio teórico, Matériau fibre unidirectionnelle, Unidirectional fiber material, Material fibra unidireccional, Micromécanique, Micromechanics, Mode rupture, Fracture mode, Modo ruptura, Modélisation, Modeling, Modelización, Mécanique rupture, Fracture mechanics, Mecánica ruptura, Méthode élément frontière, Boundary element method, Método elemento frontera, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Rupture fibre, Fibre fracture, Ruptura fibra, Résistance compression, Compressive strength, Resistencia compresión, Simulation numérique, Numerical simulation, Simulación numérica, Stratifié, Laminate, Estratificado, B. Transverse cracking, Biaxial loads, C. Micro-mechanics, and C. Numerical analysis

At present, the progress in the failure criteria of unidirectional reinforced laminates requires the study of the evolution of the mechanisms of damage at micromechanical level. The objective of this paper is the study of the influence (at micromechanical scale) of a secondary transverse load (tension or compression), perpendicular to the transverse compression nominally responsible for the failure, on the inter-fibre failure under compression. The Boundary Elements Method and Interfacial Fracture Mechanics concepts are employed. It is shown that a secondary tension accelerates the generation of failure whereas a secondary compression inhibits it.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Matériaux composites, Composites, Défaut matériau, Material defect, Defecto material, Détection défaut, Defect detection, Detección imperfección, Effet photothermique, Photothermal effects, Endommagement, Damaging, Deterioración, Ester polymère, Ester polymer, Ester polímero, Etude expérimentale, Experimental study, Estudio experimental, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Matériau composite, Composite material, Material compuesto, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Mesure température, Temperature measurement, Medida temperatura, Méthode non destructive, Non destructive method, Método no destructivo, Orientation fibre, Fiber orientation, Orientación fibra, B. Defects, D. Non destructive testing, and Modulated photothermal method

A new method dedicated to macroscopic-like defect localization in composite materials is presented in this paper. The proposed method is based on non intrusive measurements of the sample temperature resulting from a local periodic low energy heating. In such an approach, the low temperature increases of the investigated material avoid damages which can occur with usual flash techniques. Since thermal waves propagation is modified due to the heterogeneity induced by the defect, analysis of both modulus and phase lag spatial distributions provides relevant knowledge. Up to now, macroscopic-like defect detection based on local periodic heating has not been widely investigated. Thus, differences between the global approach and the local approach have to be pointed out in order to verify the local method's attractiveness. A mathematical model based on complex temperature is developed and provides a relevant predictive tool. In several configurations interest of local periodic heating is highlighted. For example, while several defects are included in the sample, the method capability to distinguish one from each other is shown considering a scanning approach. In order to validate these results, an experimental device has been developed. Several non destructive inspections are performed and defect detection is achieved using an infra-red camera providing observations of the sample surface.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Batiment. Travaux publics, Buildings. Public works, Calcul des constructions. Sollicitations, Structural analysis. Stresses, Résistance des matériaux (élasticité, plasticité, flambage, etc.), Strength of materials (elasticity, plasticity, buckling, etc.), Matériaux, Materials, Bétons. Mortiers. Coulis, Concretes. Mortars. Grouts, Généralités (composition, classification, performances, normes, brevets, etc.), General (composition, classification, performance, standards, patents, etc.), Béton de ciment, Cement concrete, Hormigón cemento, Etude théorique, Theoretical study, Estudio teórico, Matériau composite, Composite material, Material compuesto, Micromécanique, Micromechanics, Module Young, Young modulus, Módulo Young, Modèle mécanique, Mechanical model, Modelo mecánico, Modélisation, Modeling, Modelización, Mécanique rupture, Fracture mechanics, Mecánica ruptura, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété non linéaire, Non linear properties, Propiedad no lineal, Relation contrainte déformation, Stress strain relation, Relación tensión deformación, Résistance compression, Compressive strength, Resistencia compresión, Simulation numérique, Numerical simulation, Simulación numérica, B. Elasticity, B. Strength, B. Stress concentrations, and C. Micro-mechanics

In this contribution, a four-phase micromechanical model is proposed in order to simulate the non-linear instantaneous pre-peak response of cement concrete subjected to monotonically increasing loads. The non-linear behavior is attributed to the creation of cracks in the cement paste of the concrete; the effect of the cracks is taken into account by introducing equivalent voids in the cement paste. The concrete material is modeled as a four-phase composite with three different types of heterogeneities: gravel, sand and voids, embedded in a cement pure paste matrix. The composite homogenization is realized with the Mori-Tanaka method and the overall non-linear response of the concrete is determined by a secant approach. The proposed micromechanical model is able to capture peculiar aspects of the concrete stress-strain curve of uniaxial compression: in most concrete materials, a higher compressive strength is associated with a higher initial tangent Young's modulus. Further analogies between the theoretical curves of the proposed method and the experimental curves are shown.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Composite hybride, Hybrid composite, Compuesto híbrido, Délaminage, Delamination, Delaminación, Effet concentration, Concentration effect, Efecto concentración, Endommagement, Damaging, Deterioración, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Intégrité structure, Structure integrity, Integridad estructura, Matériau composite, Composite material, Material compuesto, Matériau renforcé dispersion, Dispersion reinforced material, Material renforzado dispersión, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Moulage sous vide, Vacuum molding, Moldeo en vacío, Moulage transfert, Transfer molding, Moldeo por transferencia, Méthode mesure, Measurement method, Método medida, Méthode non destructive, Non destructive method, Método no destructivo, Nanocomposite, Nanocompuesto, Nanotube carbone, Carbon nanotubes, Nanotube multifeuillets, Multiwalled nanotube, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété électrique, Electrical properties, Propiedad eléctrica, Résistance choc, Impact strength, Resistencia choque, Résistivité électrique, Electric resistivity, Resistividad eléctrica, Stratifié, Laminate, Estratificado, A. Class fibres, A. Nano-structures, B. Delamination, B. Electrical properties, and Structural health monitoring (SHM)

In the present study a technique for damage detection in nanoparticle-modified glass fibre reinforced polymer (GFRP), using in-plane and through-thickness electrical resistance measurements, is presented. Via this technique barely visible impact damages could be detected, localised and characterised (damage mapping). Dispersion of different filler contents of MWCNT and CB was achieved in a three roll mill. GFRP laminates with the modified matrix were manufactured with VARTM. Damage detection is realised measuring the electrical resistance distribution of the specimens before and after impact and the analysis of the damage correlated relative resistance changes. For the measurement a conductive silver ink electrode grid was directly applied to the specimen's surfaces, allowing a reliable localisation of the impact damages through damage mapping. Comparison between ultrasonic C-scans and the electrical damage mapping for a majority of the specimens showed a reliable correlation in the positions of the impact related delaminations. Different nanoparticle modifications of the GFRP-laminates resulted in a significant variation of the sensitivity of the damage mapping method. The found results show a large influence of the orientation of the electrodes as well as the used nanoparticles on the evaluated damage maps. Multiple impact tests showed the suitability of the developed damage mapping-technique for the characterisation of damage propagation regarding interlaminar delaminations and surface near matrix cracks.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Stratifiés, Laminates, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Fibre carbone, Carbon fiber, Fibra carbón, Fibre minérale, Mineral fiber, Fibra inorgánica, Matériau composite, Composite material, Material compuesto, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Mode rupture, Fracture mode, Modo ruptura, Moulage sous vide, Vacuum molding, Moldeo en vacío, Moulage transfert, Transfer molding, Moldeo por transferencia, Nanocomposite, Nanocompuesto, Nanotube carbone, Carbon nanotubes, Nanotube multifeuillets, Multiwalled nanotube, Propriété mécanique, Mechanical properties, Propiedad mecánica, Résistance fatigue, Fatigue strength, Resistencia fatiga, Résistance propagation fissure, Crack propagation resistance, Resistencia propagación grieta, Stratifié, Laminate, Estratificado, Tissu textile, Woven material, Tela textil, Ténacité, Fracture toughness, Tenacidad, Nanofibre carbone, Tissu carbone, Ténacité interlaminaire, A. Carbon fiber, A. Fabrics/textiles, A. Nano-structures, B. Fatigue, and B. Fracture toughness

In the present study the effect of carbon nanofiber interlayers on the fatigue crack propagation of woven fabric CFRP laminates made by VaRTM is investigated. Double cantilever beam (DCB) tests are carried out to determine the mode I static fracture toughness and mode I fatigue crack propagation curve. The experimental results clearly show that the interlaminar fracture toughness and the fatigue crack growth resistance can be substantially improved by the addition of CNF interlayers to the CFRP laminates. In more details, as far as the mode I fatigue crack tests are concerned, thanks to the addition of MWNT-7 interlayers the number of cycles to failure becomes 1.5 or more times greater than that of base laminates. Furthermore, it is found that the fatigue fracture toughness GImax (the upper limit of the energy release rate in a fatigue test) is increased by about 300%.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Domaines d'application, Application fields, Batiment. Travaux publics, Buildings. Public works, Matériaux, Materials, Matières plastiques, Plastics, Absorption énergie, Energy absorption, Absorción energía, Ecrasement, Crush, Aplastamiento, Ester polymère, Ester polymer, Ester polímero, Etude expérimentale, Experimental study, Estudio experimental, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Matériau composite, Composite material, Material compuesto, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Modèle 3 dimensions, Three dimensional model, Modelo 3 dimensiones, Modélisation, Modeling, Modelización, Moulage pultrusion, Pultrusion, Moldeo pultrusión, Onde souffle, Blast wave, Onda explosión, Produit parement, Cladding product, Producto recubrimiento, Propriété mécanique, Mechanical properties, Propiedad mecánica, Résistance choc, Impact strength, Resistencia choque, Sensibilité vitesse déformation, Strain rate sensitivity, Sensibilidad velocidad deformación, Simulation numérique, Numerical simulation, Simulación numérica, Tube, Tubo, Résistance explosion, A. Polymer-matrix composites, B. Impact behaviour, C. Numerical analysis, and D. Mechanical testing

Crushing of composite tubes under impact loading has been studied very intensively over the last few decades. On the contrary, the energy absorption of composite tubes under blast loading is much less studied, and very limited public literature is available. This paper presents the experimental testing of a sacrificial cladding structure, composed of glass/polyester tubes, under blast loading. The composite tubes show stable and progressive crushing and the peak force transferred to the non-sacrificial structure is compared for different configurations of the composite tubes. The results also show that the diffraction of the pressure wave and the skin panel that distributes the blast pressure are critical issues in the set-up of the experiments.

Chemical industry parachemical industry, Industrie chimique et parachimique, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Matériaux composites, Composites, Carbonate de calcium, Calcium carbonate, Calcio carbonato, Dissipation énergie, Energy dissipation, Disipación energía, Endommagement, Damaging, Deterioración, Etude expérimentale, Experimental study, Estudio experimental, Fibre courte, Short fiber, Fibra corta, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre verre, Glass fiber, Fibra vidrio, Matériau composite, Composite material, Material compuesto, Matériau renforcé dispersion, Dispersion reinforced material, Material renforzado dispersión, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Moulage injection, Injection molding, Moldeo por inyección, Oléfine polymère, Olefin polymer, Olefina polímero, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Propène polymère, Propylene polymer, Propeno polímero, Résistance fatigue, Fatigue strength, Resistencia fatiga, Fibre longue, A. Glass fibres, B. Fatigue, E. Injection moulding, and Hysteresis energy

In this paper the hysteresis energy density per cycle was considered as fatigue damage index to rationalise in a single scatter band the fatigue behaviour of short glass fibre reinforced polypropylene (30 wt% 1-mm-long glass fibre), long glass fibre reinforced polypropylene (30 wt% 10-mm-long glass fibre) and 42 wt% calcium carbonate filled polypropylene. Moreover the nature of such a mechanical energy was investigated to establish to which extent dissipation is due to creep strains and it was found that hysteresis energy dissipated in a unit volume of material per cycle due to visco-elasticity is negligible with respect to the total hysteresis energy.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Elasticité. Plasticité, Elasticity. Plasticity, Cisaillement, Shear, Cizalladura, Scherung, Contrainte cisaillement, Shear stress, Tensión cizallamiento, Scherspannung, Contrainte écoulement, Flow stress, Tensión flujo, Fliessspannung, Ecrouissage, Work hardening, Endurecimiento en frío, Effet contrainte, Stress effects, Grande déformation, High strain, Gran deformación, Propriété mécanique, Mechanical properties, Propiedad mecánica, Viscoplasticité, Viscoplasticity, Viscoplasticidad, Viskoplastizitaet, Torsion sous haute pression, High pressure torsion, Equivalent strain, Equivalent stress, Flow curve, and Torque/twist

The results of experiments carried out by means of high pressure torsion (HPT) are frequently described in terms of the Eichinger equivalent strain. When employed in conjunction with equivalent stresses derived using von Mises in conjunction with the Fields and Backofen analysis, the values of the work done/unit volume associated with the Eichinger-based flow curves are shown to be only a small fraction of the actual work done. By contrast, the values of the work done/unit volume that correspond to the shear stress/shear strain as well as the von Mises flow curves are in full agreement with the torque/twist work done/unit volume. When the principle of work conjugacy is employed, the Eichinger strain-based work done values are necessarily in agreement with the shear stress/shear strain and torque/twist results, but then the equivalent stresses are unrealistically high. It is concluded that only the von Mises equivalent stresses and strains should be employed in the description of HPT results and that the Eichinger equivalent strain should not be used for this purpose.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Propriétés de transport (non électroniques), Transport properties of condensed matter (nonelectronic), Diffusion dans les solides, Diffusion in solids, Electromigration, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Diagrammes de phases et microstructures développées par solidification et par transformations de phases solide-solide, Phase diagrams and microstructures developed by solidification and solid-solid phase transformations, Précipitation, Precipitation, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Elasticité. Plasticité, Elasticity. Plasticity, Constante vitesse, Rate constant, Constante velocidad, Courant continu, Direct current, Corriente contínua, Gleichstrom, Courant électrique, Electric current, Corriente eléctrica, Elektrischer Strom, Densité courant, Current density, Densidad corriente, Stromdichte, Déformation dent de scie, Serrated yielding, Effet Joule, Joule effect, Efecto Joule, Effet Portevin Le Châtelier, Portevin Le Chatelier effect, Efecto Portevin Le Chatelier, Portevin Le Chatelier Effekt, Electrodiffusion, Electrodifusión, Elektrodiffusion, Essai traction, Tension test, Ensayo tracción, Zugversuch, Instabilité, Instability, Inestabilidad, Unbestaendigkeit, Phénomène critique, Critical phenomenon, Fenómeno crítico, Phénomène transport, Transport process, Fenómeno transporte, Transporterscheinung, Propriété mécanique, Mechanical properties, Propiedad mecánica, Précipitation, Precipitation, Precipitación, Ausscheidung, Valeur critique, Critical value, Valor crítico, Kritischer Wert, Vitesse déformation, Strain rate, Velocidad deformación, Verformungsgeschwindigkeit, 6630Q, 8130M, Al-Mg alloy, Direct electric current, Electromigration, Electroplasticity, and PLC effect

The direct current-induced suppression of the Portevin - Le Chatelier (PLC) effect has been revealed and investigated in Al-5 wt% Mg and Al-6 wt% Mg alloys during tensile tests at a constant strain rate. Suppression of the PLC effect by direct electric current manifests itself as an increase in the critical strain εc for the onset of serration flow with increasing current density exceeding a certain critical value jc which depends on the weight content of Mg in Al-Mg alloy. The current density range in which the transition from a jerky tensile curve to a smooth one occurs is found to depend on the type of PLC instabilities apart from the testing temperature and an imposed strain rate. The obtained results show that the observed suppression of jerky flow by electric current is not directly associated with Joule heating per se of the whole sample. Possible mechanisms of the phenomenon are discussed.