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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, 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, 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.

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Modélisation, Modeling, Modelización, Métaux dissemblables, Dissimilar metals, Metales desemejantes, Verschiedenartige Metalle, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Bonding, Cold spray, Impact, Modelling, and SPH

In this study, the critical, maximum and optimum velocity of a single cold sprayed (CS) particle is estimated using the smoothed particle hydrodynamics (SPH) method by evaluating the impact shape coefficient of restitution, as well as the rebound and deposit energy ratio. The contact surfaces of the particle and the substrate are modelled as intersurface forces using the Dugdale-Barenblatt cohesive zone model. The application of SPH allows the simulation of the CS process without the use of mesh, thereby avoiding the disadvantages of the traditional numerical method in handling large deformations and tracing moving interfaces. The impact of CS particles is simulated using various powder and substrate materials. The influence of the materials on the optimum velocity and the coating quality is discussed. The reliability of the model is verified with CS 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, 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, 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.

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, Calcul des constructions. Sollicitations, Structural analysis. Stresses, Résistance des matériaux (élasticité, plasticité, flambage, etc.), Strength of materials (elasticity, plasticity, buckling, etc.), Durabilité. Pathologie. Réparation. Entretien, Durability. Pathology. Repairing. Maintenance, Réparation (renforcement, consolidation), Repair (reinforcement, strenthening), Adhésif, Adhesive, Adhesivo, Ancrage, Anchoring, Anclaje, 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, Maçonnerie brique, Brick masonry, Mampostería ladrillo, Mode rupture, Fracture mode, Modo ruptura, Plastique renforcé fibre carbone, Carbon fiber reinforced plastics, Propriété mécanique, Mechanical properties, Propiedad mecánica, Renforcement mécanique, Strengthening, Refuerzo mecánico, Résistance traction, Tensile strength, Resistencia tracción, Ancrage(construction béton), A. Carbon fibre, B. Debonding, B. Mechanical properties, D. Mechanical testing, and Mechanical anchor

Fiber reinforced composite materials are widely used for structural rehabilitation and retrofitting of existing buildings. Failure of not anchored CFRP reinforcements, applied to both concrete and masonry, mainly occurs in the substrate or at the bonding surface, for load values lower than the tensile strength of the composite. Mechanical anchors can effectively increase the maximum load of this type of reinforcements. Particular attention should be paid to the design and sizing of mechanical anchors so that these can produce adequate increments of both strength and ductility of the reinforcement. At the moment there are no specific rules or reliable predictive formulas that adequately support designers in the design choices and sizing of anchors. Of course, these can be defined only after collection of an extensive experimental database that highlights the peculiar characteristics of these reinforcements also with reference to the substrate material. In this context, the present work describes the results of an experimental campaign carried out on brick specimens reinforced with CFRP strips, anchored to the substrate by CFRP spike anchors. Almost all research in the literature about this topic refers to the use of this reinforcement technique for concrete structural elements. Studies concerning masonry are limited: this work contributes to bridge part of this gap. Plane CFRP reinforcement strips generally exhibit brittle failure mode. The experimental campaign reported in this paper shows that properly designed mechanical anchors increase both the failure load and the ductility of the reinforcement.

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, Durabilité. Pathologie. Réparation. Entretien, Durability. Pathology. Repairing. Maintenance, Réparation (renforcement, consolidation), Repair (reinforcement, strenthening), Aptitude écoulement, Flowability, Fluidez, Béton armé fibre, Fiber reinforced concrete, Hormigón fibra armada, Béton haute performance, High strength concrete, Hormigón alta resistencia, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Fibre acier, Steel fiber, Fibra acero, Fibre métal, Metal fiber, Fibra metálica, Fibre naturelle, Natural fiber, Fibra natural, Fibre synthétique, Synthetic fiber, Fibra sintética, Fibre végétale, Plant fiber, Fibra vegetal, Formulation béton, Concrete mix design, Formulación hormigón, Matériau construction, Construction materials, Material construcción, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété technologique, Technological properties, Propiedad tecnológica, Relation formulation propriété, Property formulation relationship, Relación formulación propiedad, Réparation, Repair, Reparación, Résistance compression, Compressive strength, Resistencia compresión, Résistance flexion, Bending strength, Resistencia flexión, Résistance traction, Tensile strength, Resistencia tracción, Fibre palmier, A. Fibers, A. hybrid, B. Mechanical properties, D. Mechanical testing, and Repair materials

The maintenance and the repair of concrete structures have become more needed in the field of Civil Engineering. The selection of repair materials for concrete structures requires an understanding of the material behavior. Therefore, this research is conducted to provide a clear indication and understanding of the behavior and structural performance in engineering construction. The combined system of substrate concrete with different mix proportions of flowable high strength system reinforced by hybrid fibers was used to study its mechanical properties. The experimental tests are: compressive strength, splitting tensile strength, flexural strength and pull-out test. It was found that the high strength flowing concrete (HSFC) provides the best performance when the compressive strength of the repaired system is needed, whereas the high strength flowable mortar (HSFM) has the best performance when the tensile strength of repaired system is required. The best value of pull out test was obtained from using the flowable high strength mortar reinforced with 1.5% steel fiber +0.25% palm fiber +0.25% Barchip fiber as the repair material, whereas, the least value of pull-out test was obtained from samples using epoxy.

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 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, Modélisation, Modeling, Modelización, Méthode mesure, Measurement method, Método medida, Orientation fibre, Fiber orientation, Orientación fibra, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Résistance cisaillement, Shear strength, Resistencia cizallamiento, Simulation numérique, Numerical simulation, Simulación numérica, Stratifié, Laminate, Estratificado, A. Laminate, A. Polymer―matrix composites (PMCs), C. Transverse cracking, and Stiffness degradation

Matrix damage, in the form of cracks parallel to the fiber due both to in-plane tensile loading perpendicular to the fibers and to in-plane shear loading, is a common failure mode for composite structures, yet little is known concerning their interaction. Past work has focused on experimental and analytical studies of axial and transverse stiffness reduction due to matrix cracks. By comparison, there is relatively little experimental work addressing shear modulus degradation from matrix damage. In this paper, a modified Isoipescu coupon is proposed to study the shear modulus degradation due to loading perpendicular to the fibers direction. The layup and coupon geometry were selected in a way that controls the severity of the damage and allows the measurement of shear and transverse stiffness degradation in the same coupon. The proposed method showed good agreement with results from tubular specimens and has advantages of simplified specimen fabrication using standard test fixtures. The results provided the first experimental comparison of shear modulus reduction, from transverse damage, to the predictive models. The results were compared with existing analytical and numerical models which over predicted the observed shear modulus reduction.

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, Déchet plastique, Plastic waste, Residuo plástico, Etude expérimentale, Experimental study, Estudio experimental, Extrusion, Extrusión, Fibre lin, Flax fiber, Fibra lino, Fibre minérale, Mineral fiber, Fibra inorgánica, Fibre naturelle, Natural fiber, Fibra natural, Fibre verre, Glass fiber, Fibra vidrio, Fibre végétale, Plant fiber, Fibra vegetal, Matériau composite, Composite material, Material compuesto, Matériau recyclé, Recycled material, Material reciclado, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Moulage injection, Injection molding, Moldeo por inyección, Oléfine polymère, Olefin polymer, Olefina polímero, Panneau fibre, Fiberboard, Panel fibra, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété traction, Tensile property, Propiedad tracción, Propène polymère, Propylene polymer, Propeno polímero, Recyclage, Recycling, Reconversión, Relation mise en oeuvre propriété, Property processing relationship, Relación puesta en marcha propiedad, Résistance choc, Impact strength, Resistencia choque, Résistance flexion, Bending strength, Resistencia flexión, Longueur fibre, A. Fibres, A. Wood, B. Mechanical properties, and E. Recycling

Composites of polypropylene, substitutable for a given application and reinforced with: Medium Density Fibreboard fibre (MDF) (40 wt%); flax (30 wt%); and glass fibre (20 wt%), were evaluated after 6 injection moulding and extrusion reprocessing cycles. Of the range of tensile, flexural and impact properties examined, MDF composites showed the best mean property retention after reprocessing (87%) compared to flax (72%) and glass (59%). After 1 reprocessing cycle the glass composite had higher tensile strength (56.2 MPa) compared to the MDF composite (44.4) but after 6 cycles the MDF was stronger (35.0 compared to 29.6 MPa for the glass composite). Property reductions were attributed to reduced fibre length. MDF fibres showed the lowest reduction in fibre length between 1 and 6 cycles (39%). compared to glass (51%) and flax (62%). Flax fibres showed greater increases in damage (cell wall dislocations) with reprocessing than was shown by MDF fibres.

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, Agent nucléant, Nucleating agent, Agente germinación, Amide 12 polymère, Amide 12 polymer, Amida 12 polímero, Cinétique, Kinetics, Cinética, Cristallinité, Crystallinity, Cristalinidad, Cristallisation état fondu, Melt crystallization, Cristalización estado fundido, Effet concentration, Concentration effect, Efecto concentración, Etude expérimentale, Experimental study, Estudio experimental, Extrusion, Extrusión, Matériau composite, Composite material, Material compuesto, Matériau renforcé dispersion, Dispersion reinforced material, Material renforzado dispersión, Module Young, Young modulus, Módulo Young, Molybdène Iodosulfure, Molybdenum Iodides sulfides, Molibdeno Iodosulfuro, Morphologie, Morphology, Morfología, Nanocomposite, Nanocompuesto, Nanofil, Nanowires, Polymère aliphatique, Aliphatic polymer, Polímero alifático, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété thermique, Thermal properties, Propiedad térmica, A Nano-structures, B. Mechanical properties, B. Thermal properties, and D. Electron microscopy

Nanocomposites consisting of PA12 and Mo6S3I6 nanowires at concentrations of 0.5, 1.0 and 2.0 wt.% were prepared by extrusion and characterised. Using electron microscopy it was confirmed that bundles of nanowires were present, whose size increases with increasing concentrations. Differential dynamic calorimetry showed that the nanowires act as a nucleating agent, increasing the crystallization rate and the overall degree of crystallinity, but at the same time the size of the crystals is decreased. As a result, Young's modulus was increased by 15% with the addition of only 0.5 wt.% of Mo6S3I6. The improved mechanical properties are attributed to changes in the polymer morphology and crystallinity.

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, Aniline polymère, Aniline polymer, Anilina polímero, Constante diélectrique, Permittivity, Constante dieléctrica, Effet concentration, Concentration effect, Efecto concentración, Epoxyde résine, Epoxy resin, Epóxido resina, Etude expérimentale, Experimental study, Estudio experimental, Matériau composite, Composite material, Material compuesto, Mélange polymère, Polymer blends, Nanocomposite, Nanocompuesto, Nanotube carbone, Carbon nanotubes, Nanotube multifeuillets, Multiwalled nanotube, Percolation, Percolación, Perte diélectrique, Dielectric loss, Pérdida dieléctrica, Polymère aromatique, Aromatic polymer, Polímero aromático, Polymère conducteur, Conducting polymers, Polymère ramifié, Branched polymer, Polímero ramificado, Propriété diélectrique, Dielectric properties, Propiedad dieléctrica, Propriété électrique, Electrical properties, Propiedad eléctrica, Préparation, Preparation, Preparación, A. Hybrid, A. Polymer-matrix composites (PMCs), and B. Electrical properties

New high-k composites based on unique multi-branched polyaniline (MSiPA)/multi-walled carbon nanotube (MWCNT) hybrids and epoxy (EP) resin were prepared. MSiPA/MWCNT/EP composite has much higher dielectric constant and lower dielectric loss than MWCNT/EP composite with the same loading of MWCNTs. Dielectric constant and loss at 100 Hz of MSiPA3/MWCNTO.4/EP composite are 2.4 and 3.3 × 10-3 times the value of MWCNT0.4/EP composite, respectively; meanwhile the percolation threshold of MSiPA/MWCNT0.4/EP composites is as low as 0.51 wt%, remarkably lower than that of available composites with coated MWCNTs. These attractive results are attributed to unique structures of MSiPA/MWCNT hybrids. The multi-branched structure, large polyaniline concentration and flexible Si-O chains make MSiPA have big ability to be coated on surfaces of MWCNTs through π-π interaction. Different from MWCNTs, MSiPA/MWCNT hybrids have good dispersion in EP matrix, forming more micro-capacitors and avoiding the loss of conductive currents. Equivalent circuits were built to further discuss the origin behind.

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, Alvéolaires, Cellular, Matériaux composites, Composites, Matière plastique, Plastics, Material plástico, Argile, Clay, Arcilla, Composite hybride, Hybrid composite, Compuesto híbrido, Densité, Density, Densidad, Effet température, Temperature effect, Efecto temperatura, Epoxyde résine, Epoxy resin, Epóxido resina, 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 dispersion, Dispersion reinforced material, Material renforzado dispersión, Matériau renforcé fibre, Fiber reinforced material, Material reforzado fibra, Microsphère, Microsphere, Microsfera, Montmorillonite, Montmorilonita, Morphologie, Morphology, Morfología, Plastique alvéolaire, Cellular plastic, Plástico espumoso, Propriété mécanique, Mechanical properties, Propiedad mecánica, Résistance compression, Compressive strength, Resistencia compresión, Microsphère expansible, A. Foams, A. Polymer-matrix composites (PMCs), B. Mechanical properties, and B. Microstructures

Expandable microspheres/epoxy foams with different densities and microstructures were prepared by changing the foaming temperature and the precuring extent. The microstructure of foams reveals a homogeneous distribution of cells at high precuring extent and high foaming temperature, while small cells size at high precuring extent and low foaming temperature. Furthermore, the compressive properties of epoxy foams were investigated. The compressive strength and modulus of the foam exhibited a power-law dependence with respect to density. By optimizing the foaming temperature and the precuring extent, epoxy foams with homogeneous cells and stable compressive property can be obtained. Fracture surface showed that deformed microspheres and less debris were observed at relatively high-density foams.