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Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Batiment. Travaux publics, Buildings. Public works, Construction (bâtiments et ouvrages), Construction (buildings and works), Structure construction, Building structure, Structure en béton, Concrete structure, Structure en béton armé, Reinforced concrete structure, Analyse structurale, Structural analysis, Análisis estructural, Autosimilitude, Selfsimilarity, Autosimilitud, Béton armé, Reinforced concrete, Hormigón armado, Capacité portante, Loadbearing capacity, Capacidad soporte, Cohésion, Cohesion, Cohesión, Délaminage, Delamination, Delaminación, Effet bord, Edge effect, Efecto borde, Effet dimensionnel, Size effect, Efecto dimensional, Effet échelle, Scale effect, Efecto escala, Extrémité cohésive, Cohesive end, Extremidad cohesiva, Fissure interface, Interface crack, Fisura interfase, Gradient déformation, Strain gradient, Gradiente deformación, Grande déformation, High strain, Gran deformación, Image numérique, Digital image, Imagen numérica, Plastique renforcé fibre carbone, Carbon fiber reinforced plastics, Plastique renforcé fibre, Fibre reinforced plastics, Plástico reforzado fibra, Poutre renforcée, Reinforced beam, Viga reforzada, Propagation fissure, Crack propagation, Propagación fisura, Propriété interface, Interface properties, Propiedad interfase, Relation contrainte déformation, Stress strain relation, Relación tensión deformación, Rupture glissement, Shear fracture, Rotura deslizamiento, Structure renforcée, Reinforced structure, Estructura reforzada, Traitement image, Image processing, Procesamiento imagen, Cohesive material law, Concrete, Debonding, FRP sheets, Fracture, Interface, Slip, and Width effect

The increasing use of carbon fiber reinforced polymer (FRP) sheets for strengthening existing reinforced concrete beams has generated considerable research interest in understanding the debonding mechanism of failure in such systems. The influence of the width of the FRP on the load-carrying capacity is investigated in this paper. The interfacial crack propagation and strain distribution during shear debonding are studied using a full-field optical technique known as digital image correlation. The results indicate the development of high stress/strain gradients at the interface as a consequence of the relative slip between the FRP and the concrete. The interface stress transfer between the FRP and concrete produces axial strain gradients in the FRP along its length. In the vicinity of the edges along the width of the FRP, edge regions comprising of both FRP and concrete are established. The edge region is characterized by high strain gradients in a direction perpendicular to the length and is of fixed width throughout the debonding process. The size of the edge regions is also found to be quite independent of the width of the FRP. Mode-II fracture condition exists in the interface directly below the FRP away from the edge regions. The interfacial crack is shown to be associated with a cohesive stress transfer zone of fixed length. During debonding, the stress transfer zone is shown to propagate in a self-similar manner at a fixed load. The interface fracture properties obtained from the portion of FRP away from the edge regions are shown to be independent of the FRP width. It is shown that when the width of concrete is larger than that required for establishing the edge regions, the nominal stress at debonding increases with an increase in the width of FRP. The scaling in the load carrying capacity during shear debonding is shown to be the result of the edge regions which do not scale with the width of the FRP.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Inélasticité (thermoplasticité, viscoplasticité...), Inelasticity (thermoplasticity, viscoplasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Propriétés mécaniques et acoustiques de l'état condensé, Mechanical and acoustical properties of condensed matter, Propriétés mécaniques des solides, Mechanical properties of solids, Fluage, Creep, Sciences appliquees, Applied sciences, Genie mecanique. Construction mecanique, Mechanical engineering. Machine design, Constructions métalliques, Steel design, Réservoirs métalliques et enceintes sous pression; chaudronnerie, Steel tanks and pressure vessels; boiler manufacturing, Acier construction, Structural steel, Acero construcción, Assemblage soudé, Welded joints, Fluage, Creep, Haute pression, High pressure, Haute température, High temperature, Alta temperatura, Métal, Metals, Rupture, Ruptures, Récipient sous pression, Pressure vessels, Système incertain, Uncertain systems, Sécurité, Safety, Zone thermiquement affectée, Heat affected zone, 2.25Cr-1Mo steel pipe, Hydrogen attack, ICHAZ, Type IV, and Weldments

The standard 2.25Cr-1Mo steel, has been used for most of the hydroprocessing reactors built during the 30 years up to the end of the 1990's. Under service conditions, the steel, and in particular its weldments, may experience degradation by hydrogen attack, or high-temperature hydrogen attack (HTHA), which is responsible for several failures and even casualties occurring in the history of the industry. The selection of the structural steels is still based on the empirical Nelson curves which, among other limitations, do not provide information on the behaviour of weldments. This causes uncertainties in the definition of the safety boundaries for operation of pressurized components in the petrochemical industry. The results of the present study confirm that weldments are a weak point of the pressurized components and suggest that the HAZ, and in particular the ICHAZ, is the most sensitive metallurgical zone to hydrogen attack.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Inélasticité (thermoplasticité, viscoplasticité...), Inelasticity (thermoplasticity, viscoplasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Méthodes de mesure et d'essai, Measurement and testing methods, Acier construction, Structural steel, Acero construcción, Effet fermeture fissure, Crack closure effect, Efecto ciere fisura, Etalonnage, Calibration, Contraste, Etude expérimentale, Experimental study, Estudio experimental, Extrémité fissure, Crack tip, Extremidad fisura, Fissure fatigue, Fatigue crack, Fisura fatiga, Inélasticité, Inelasticity, Inelasticidad, Jauge contrainte, Resistance strain gauge, Gauge tensión, Mesure contrainte, Stress measurement, Mesure déformation, Deformation measurement, Medición deformación, Métal, Metal, Méthode globale locale, Global local method, Método global local, Méthode élément fini, Finite element method, Método elemento finito, Plasticité, Plasticity, Plasticidad, Potentiel complexe, Complex potential, Potencial complejo, Propagation fissure, Crack propagation, Propagación fisura, Zone plasticité, Plasticity zone, Zona plasticidad, Crack closure, Elastic complex potentials, Local compliance measurements, and Strip-Yield model

The plasticity-induced crack closure phenomenon is the leading mechanism which controls the main effects on fatigue crack growth (e.g. stress ratio and load interaction effects) in metallic materials. Experimental tests, consisting mainly in global and/or local compliance measurements of the considered specimen, are usually carried out to quantify the physical phenomenon, but some aspects concerning the elaboration of acquired local compliance signals are not yet clear. From the analytical point of view, the so-called Strip-Yield model has proven to be the most versatile and powerful tool for estimating crack closure levels, but its application to structural steels is not yet straightforward due to the delicate calibration process. The present work tries to add some new ideas on the elaboration of local compliance experimental data, obtained from a M( T) specimen, simulating the measurements by means of an optimised Strip-Yield model implementation enriched by a novel module based on the Westergaard's elastic complex potentials. The application of the method to the calibration of the Strip-Yield model has been already successfully faced elsewhere, so here the analytical results gave the possibility, together with dedicated FEM analyses, to investigate some of the different parameters and to state some conclusions about the reliability and applicability of local compliance measurements.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Elasticité statique (thermoélasticité...), Static elasticity (thermoelasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Contact mécanique (frottement...), Mechanical contact (friction...), Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Radiotherapie. Traitement instrumental. Physiotherapie. Reeducation. Readaptation, orthophonie, crenotherapie. Traitement dietetique et traitements divers (generalites), Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects), Technologie. Biomatériaux. Equipements. Matériel. Appareillage, Technology. Biomaterials. Equipments. Material. Instrumentation, Amorçage fissure, Crack initiation, Iniciación grieta, Analyse statistique, Statistical analysis, Análisis estadístico, Approche probabiliste, Probabilistic approach, Enfoque probabilista, Assemblage collé, Adhesive joint, Ensambladura pegada, Biomatériau, Biomaterial, Ciment, Cement, Cemento, Contact mécanique, Mechanical contact, Contacto mecánico, Contrainte résiduelle, Residual stress, Tensión residual, Dentine, Dentin, Dentina, Dentisterie, Dentistry, Odontología, Etude expérimentale, Experimental study, Estudio experimental, Extrémité cohésive, Cohesive end, Extremidad cohesiva, Fissure interne, Internal crack, Fisura interna, Indentation, Indentación, Modélisation, Modeling, Modelización, Méthode élément fini, Finite element method, Método elemento finito, Pontage fissure, Crack bridging, Ponteado fisura, Retrait, Shrinkage, Retiro, Rupture, Ruptura, Vitrocéramique, Glass ceramics, Vidriocerámica, Adhesive resin cement, Ceramics, Dental restoration, Failure probability, and Finite element

The goal of this work is to quantitatively examine the effect of adhesive resin cement on the probability of crack initiation from the internal surface of ceramic dental restorations. The possible crack bridging mechanism and residual stress effect of the resin cement on the ceramic surface are examined. Based on the fracture-mechanics-based failure probability model, we predict the failure probability of glass-ceramic disks bonded to simulated dentin subjected to indentation loads. The theoretical predictions match experimental data suggesting that both resin bridging and shrinkage plays an important role and need to be considered for accurate prognostics to occur.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Inélasticité (thermoplasticité, viscoplasticité...), Inelasticity (thermoplasticity, viscoplasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Propriétés mécaniques et acoustiques de l'état condensé, Mechanical and acoustical properties of condensed matter, Propriétés mécaniques des solides, Mechanical properties of solids, Fluage, Creep, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Soudage, Welding, Acier, Steel, Acero, Assemblage soudé, Welded joint, Ensamblaje soldado, Schweissverbindung, Contact métal métal, Metal metal contact, Contacto metal metal, Couche interfaciale, Interfacial layer, Capa interfacial, Effet non linéaire, Non linear effect, Efecto no lineal, Essai fatigue, Fatigue test, Ensayo fatiga, Dauerschwingversuch, Essai fluage, Creep test, Prueba arrastre, Kriechversuch, Essai propagation fissure, Fracture toughness test, Prueba propagación fisuras, Rissausbreitungsversuch, Essai traction, Tension test, Ensayo tracción, Zugversuch, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Fatigue, Fatiga, Ermuedung, Fissure fatigue, Fatigue crack, Fisura fatiga, Ermuedungsriss, Fluage, Creep, Fluencia, Kriechen, Limite élasticité, Yield strength, Límite elasticidad, Streckgrenze, Métal, Metal, Metalle, Propagation fissure, Crack propagation, Propagación fisura, Rissausbreitung, Revenu, Tempering, Rupture fluage, Creep fracture, Ruptura fluencia, Kriechbruch, Réparation, Repair, Reparación, Reparatur, Soudage, Welding, Soldadura, Schweissen, Traitement thermique, Heat treatment, Tratamiento térmico, Waermebehandlung, Turbine vapeur, Steam turbine, Turbina vapor, Dampfturbine, Ténacité, Fracture toughness, Tenacidad, Bruchzaehigkeit, Variabilité, Variability, Variabilidad, 1Cr-1Mo-0.25 steel, Creep-fatigue, Turbine casings, and Welds

An experimental study was conducted to assess the structural performance of repair welds in an ex-service 1Cr-1Mo-0.25V steam turbine casing material. Material from two weld techniques, one involving a post-weld heat-treatment that produced undermatched welds and the other involving a temper bead welding technique that produced overmatched welds were tested. Both welding techniques were implemented in two base metal conditions giving rise to four different welds and two different base metal conditions. The tests conducted included tensile tests, creep tests, fracture toughness tests, fatigue crack growth tests, creep crack growth tests, and creep-fatigue crack growth tests on the base metal, weld metal and the weldment region. The yield strength of the weld metal in the undermatched condition was approximately 10% lower than the base metal, while the weld metal in the overmatched condition had a yield strength that was 30% higher than the base metal at 565 °C. The creep deformation rates in the undermatched welds were 60 times faster than the base metal at a stress of 207 MPa. In the overmatched welds, the creep rates at 207 MPa were about 2.8 times faster in one case and 2.8 times slower in the other. The crack path in fracture toughness specimens followed the interface between the transition layer and the weaker of the weld metal and the base metal. The J-resistance curves for the weldments at 565 °C showed significant variability among duplicate samples from the same welds. This scatter was caused by the variability in the location of the precrack with respect to the fusion line and the location of the low fracture toughness region in the weldment. This behavior was explained using a novel approach for characterizing the fracture of welds. The creep-fatigue crack growth rates at equivalent (Ct)avg values in undermatched welds was higher than the crack growth rates in the overmatched weld samples. In all cases under creep-fatigue, the crack appeared to grow in the weaker of the base metal and the weld metal. Recommendations for future work are provided to enhance the theoretical underpinnings of the nonlinear fracture mechanics framework to rigorously address fracture and crack growth in welds.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Elasticité statique (thermoélasticité...), Static elasticity (thermoelasticity...), Inélasticité (thermoplasticité, viscoplasticité...), Inelasticity (thermoplasticity, viscoplasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Soudage, Welding, Acier haute résistance, High strength steel, Acero alta resistencia, Hochfester Stahl, Analyse contrainte, Stress analysis, Análisis tensión, Spannungsanalyse, Analyse dimensionnelle, Dimensional analysis, Análisis dimensional, Assemblage soudé, Welded joint, Ensamblaje soldado, Schweissverbindung, Contrainte résiduelle, Residual stress, Tensión residual, Eigenspannung, Elastoplasticité, Elastoplasticity, Elastoplasticidad, Essai traction, Tension test, Ensayo tracción, Zugversuch, Fissure, Crack, Fisura, Riss, Haute température, High temperature, Alta temperatura, Hochtemperatur, Intégrale J, J integral, Integral J, J Integral, Inélasticité, Inelasticity, Inelasticidad, Modélisation, Modeling, Modelización, Métal, Metal, Metalle, Méthode élément fini, Finite element method, Método elemento finito, Finite Element Methode, Propriété thermique, Thermal properties, Propiedad térmica, Thermische Eigenschaft, Propriété thermomécanique, Thermomechanical properties, Propriedad termomecánica, Rupture, Ruptura, Bruch, Résistance traction, Tensile strength, Resistencia tracción, Zugfestigkeit, Soudage, Welding, Soldadura, Schweissen, Transformation phase, Phase transformation, Transformación fase, Phasenumwandlung, Zone thermiquement affectée, Heat affected zone, Zona termoafectada, Waermeeinflusszone, J-integral, Martensite phase transformation, and Residual stress relaxation

This study presented the characteristics of residual stresses in welds of high strength steels (POSTEN60,POSTEN80) whose tensile strengths were 600 MPa and 800 MPa, respectively. Three-dimensional thermal elastic-plastic analyses were conducted to investigate the characteristics of welding residual stresses in welds of high strength steels through the thermal and mechanical properties at high temperatures obtained from the elevated temperature tensile tests. A finite element analysis method which can calculate the J-integral for a crack in a residual stress field was developed to evaluate the J-integral for a centre crack when mechanical stresses were applied in conjunction with residual stresses. The results show that the volumetric changes associated with the austenite to martensite phase transformation during rapid cooling after welding of high strength steels significantly influence on the development of residual stresses in the weld fusion zone and heat-affected zone. For a centre crack in welds of high strength steels where only residual stresses are present, increased tensile strength of the steel, increased the J-integral values. The values of the J-integral for the case when mechanical stresses are applied in conjunction with residual stresses are larger than those for the case when only residual stresses are present.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Elasticité statique (thermoélasticité...), Static elasticity (thermoelasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Vertebres: systeme osteoarticulaire, muscle strie, Vertebrates: osteoarticular system, musculoskeletal system, Squelette et articulations, Skeleton and joints, Sciences medicales, Medical sciences, Radiotherapie. Traitement instrumental. Physiotherapie. Reeducation. Readaptation, orthophonie, crenotherapie. Traitement dietetique et traitements divers (generalites), Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects), Technologie. Biomatériaux. Equipements. Matériel. Appareillage, Technology. Biomaterials. Equipments. Material. Instrumentation, Analyse contrainte, Stress analysis, Análisis tensión, Analyse risque, Risk analysis, Análisis riesgo, Biomatériau, Biomaterial, Critère rupture, Fracture criterion, Criterio ruptura, Isotropie transverse, Transverse isotropy, Isotropia transversa, Modélisation, Modeling, Modelización, Méthode élément fini, Finite element method, Método elemento finito, Os cortical, Cortical bone, Hueso cortical, Plan expérience, Experimental design, Plan experiencia, Rupture fragile, Brittle fracture, Ruptura frágil, Système ostéoarticulaire, Osteoarticular system, Sistema osteoarticular, Tissu, Tissue, Tejido, Anisotropic behaviour, and Colles' fracture

The primary objective of this work is to outline a simple methodology for the evaluation of the risk of cortical bone fracture in the distal radius in the event of a fall from standing height onto an outstretched hand. The approach involves conducting an elastic finite element (FE) analysis wherein the cortical bone is considered to be a transversely-isotropic material and, subsequently, verifying the admissibility of the stress field. The latter is based on a proposed macroscopic fracture criterion, which takes into account the anisotropic nature of the cortical tissue. The methodology is illustrated by a numerical example, which involves FE simulation of an experimental test designed to produce a Colles' fracture of the radius.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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...), Fatigue, Fatiga, Fissure fatigue, Fatigue crack, Fisura fatiga, Propagation fissure, Crack propagation, Propagación fisura, Rupture, Ruptura, Cracks, Paris, Quantized fracture mechanics, and Wöhler

Generalizations and unification of the celebrated Paris' and Wöhler's laws for fatigue crack propagation are derived by applying the recently developed quantized (or finite) fracture mechanics. In particular, three generalized Paris', Wöhler's or unified laws are proposed and compared, demonstrating their applicability for predicting the life time of structures containing from small (the Wöhler's regime) to large (the Paris' regime) propagating fatigue cracks.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Vibration, onde mécanique, stabilité dynamique (aéroélasticité, contrôle vibration...), Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Radiotherapie. Traitement instrumental. Physiotherapie. Reeducation. Readaptation, orthophonie, crenotherapie. Traitement dietetique et traitements divers (generalites), Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects), Technologie. Biomatériaux. Equipements. Matériel. Appareillage, Technology. Biomaterials. Equipments. Material. Instrumentation, Arthropoda, Insecta, Invertebrata, Lepidoptera, Constante élasticité, Elastic constant, Constante elasticidad, Délaminage, Delamination, Delaminación, Endommagement, Damaging, Deterioración, Eprouvette préfissurée, Precracked specimen, Probeta preagrietada, Essai dynamique, Dynamic test, Ensayo dinámico, Essai mécanique, Mechanical test, Ensayo mecánico, Essai statique, Static test, Ensayo estático, Essai thermique, Thermal test, Prueba térmica, Essai traction, Tension test, Ensayo tracción, Matériau gradient fonctionnel, Functionnally graded material, Material gradiente functional, Mesure, Measurement, Medida, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Microstructure, Microestructura, Module Young, Young modulus, Módulo Young, Module déformation, Deformation modulus, Módulo deformación, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété thermomécanique, Thermomechanical properties, Propriedad termomecánica, Relation structure propriété, Property structure relationship, Relación estructura propiedad, Rupture, Ruptura, Résistance traction, Tensile strength, Resistencia tracción, Section variable, Variable section, Sección variable, Ver à soie, Silkworm, Gusano de seda, Vibration, Vibración, Biomaterial, Biomimetics, Mechanical property, Pelade, and Silkworm cocoon

The pelade, the innermost layer of silkworm cocoon next to the chrysalis, has special microstructures, mechanical properties and protective functions distinctly different from those of all the other layers. In the present paper, a series of static tensile tests and dynamic mechanical thermal analysis were performed for the first time to measure the mechanical properties of pelades, including Young's modulus, tensile strength and thermomechanical parameters. The fracture process of precracked pelade specimens was observed by in-situ scanning electron microscopy under tension. It is found that the Young's modulus, tensile strength, storage modulus and loss modulus of cocoon pelades are superior to the corresponding thickness-averaged values of a complete silkworm cocoon. The damage and fracture process of pelades involve delamination, silk breaking and damage localization band. The results indicate that silkworm caterpillars can be appreciated as sophisticated sewers to make anisotropic and optimized structures of cocoons with both protective functions and mechanical properties varying in their thickness direction. The present study might be helpful to guide biomimetic design of novel safe-guarding materials and structures from both the viewpoints of microstructures and spatial functional gradients.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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...), Méthodes de mesure et d'essai, Measurement and testing methods, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Acier faiblement allié, Low alloy steel, Acero débilmente aliado, Niedriglegierter Stahl, Contrainte triaxiale, Triaxial stress, Tensión triaxial, Dreiachsige Spannung, Cristal cubique centré, BCC crystals, Cristal cúbico centrado, Kubisch raumzentrierte Struktur, Ductilité, Ductility, Ductilidad, Verformungsfaehigkeit, Effet température, Temperature effect, Efecto temperatura, Temperatureinfluss, Essai non destructif, Non destructive test, Ensayo no destructivo, Zerstoerungsfreie Pruefung, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Identification système, System identification, Identificación sistema, Loi Weibull, Weibull distribution, Ley Weibull, Micromécanique, Micromechanics, Microstructure, Microestructura, Mikrogefuege, Modélisation, Modeling, Modelización, Métal, Metal, Metalle, Rupture clivage, Cleavage fracture, Fractura transcristalina, Spaltbruch, Rupture ductile, Ductile fracture, Ruptura dúctil, Verformungsbruch, Température transition, Transition temperature, Temperatura transición, Uebergangstemperatur, Théorie non locale, Non local theory, Teoría no local, Transition ductile fragile, Ductile brittle transition, Transición ductil frágil, Uebergang duktil sproed, CDM, Ductile failure, Fracture, Local approach, and Stress triaxiality

Fracture of BCC metals is a temperature dependent process characterized by a temperature transition regime where material failure is the result of the competing action of two different mechanisms of rupture, namely, cleavage and ductile fracture. In this paper, two micromechanics based methodologies, the local approach and a non-linear CDM model, are used to model fracture processes in the temperature transition regime for a low alloy steel. The study revealed that approaching the nihil ductility temperature (NDT), the identification procedure for the material parameters needed in the local approach becomes no longer stable resulting in a non unique set of σW and m values. This occurrence can be used to discriminate in the experimental data set those data failed in a non-complete brittle manner. Using m exponent equal to 4, a linear dependency, between σW and Kj, also in upper shelf regime, is demonstrated.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Inélasticité (thermoplasticité, viscoplasticité...), Inelasticity (thermoplasticity, viscoplasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Propriétés mécaniques et acoustiques de l'état condensé, Mechanical and acoustical properties of condensed matter, Propriétés mécaniques des solides, Mechanical properties of solids, Fluage, Creep, Acier inoxydable, Stainless steel, Acero inoxidable, Amorçage fissure, Crack initiation, Iniciación grieta, Assemblage soudé, Welded joint, Ensamblaje soldado, Ductilité, Ductility, Ductilidad, Eprouvette préfissurée, Precracked specimen, Probeta preagrietada, Essai fluage, Creep test, Prueba arrastre, Essai matériau, Material testing, Control material, Essai traction compression, Tension compression fatigue test, Ensayo tracción compresión, Essai éprouvette compacte, Compact tension test, Ensayo alargamiento probeta compacta, Fissure, Crack, Fisura, Fluage, Creep, Fluencia, Matériau homogène, Homogeneous material, Material homogéneo, Modélisation, Modeling, Modelización, Norme ASTM, ASTM standard, Norma ASTM, Propagation fissure, Crack propagation, Propagación fisura, Rupture fluage, Creep fracture, Ruptura fluencia, Ténacité, Fracture toughness, Tenacidad, Zone thermiquement affectée, Heat affected zone, Zona termoafectada, 316 Stainless steel, C*, Creep crack growth, Heat affected zone (HAZ), and Weldments

Creep crack growth testing of macroscopically homogeneous materials is well established and standardised test procedures are detailed in ASTM E1457. In ASTM E1457 the use of the compact tension C(T) specimen is specified and crack growth data are interpreted using the fracture mechanics parameter C*. The resulting benchmark crack growth data are used in assessment procedures, together with estimates of the value of C* in the component, to predict creep crack growth behaviour. In this work, the results of a series of creep crack growth tests performed on a Type 316 stainless steel weldment at a temperature of 550 °C are presented. The initial crack is located within the heat affected zone (HAZ) of the weldment. Since there are currently no agreed methods for determining C* in inhomogeneous laboratory specimens, this paper examines the application of procedures in ASTM E1457 for the characterisation of crack growth in weldments. In addition, the creep toughness parameter Kcmat is evaluated for the material. It is shown that the creep crack growth rates in the weldment may be described by the C* values obtained following ASTM E1457 in conjunction with parent material properties. Comparison of the results with similar data for Type 316H stainless steel parent material shows that the crack growth rates for the crack located within the HAZ are higher and the initiation times lower than the parent values, for the range of test conditions examined. Simple analytical models based on ductility exhaustion arguments have been shown to bound the crack initiation and growth data for the weldment.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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 biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Radiotherapie. Traitement instrumental. Physiotherapie. Reeducation. Readaptation, orthophonie, crenotherapie. Traitement dietetique et traitements divers (generalites), Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects), Technologie. Biomatériaux. Equipements. Matériel. Appareillage, Technology. Biomaterials. Equipments. Material. Instrumentation, Biomatériau, Biomaterial, Dentisterie, Dentistry, Odontología, Délaminage, Delamination, Delaminación, Eprouvette préfissurée, Precracked specimen, Probeta preagrietada, Essai traction compression, Tension compression fatigue test, Ensayo tracción compresión, Essai éprouvette compacte, Compact tension test, Ensayo alargamiento probeta compacta, Extrémité fissure, Crack tip, Extremidad fisura, Fatigue, Fatiga, Fissure interface, Interface crack, Fisura interfase, Inclusion solide, Solid inclusion, Inclusión sólida, Micromécanique, Micromechanics, Microscopie force atomique, Atomic force microscopy, Microscopía fuerza atómica, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Microscopie électronique, Electron microscopy, Microscopía electrónica, Microstructure, Microestructura, Modélisation, Modeling, Modelización, Méthode élément fini, Finite element method, Método elemento finito, Nanocomposite, Nanocompuesto, Nanoparticule, Nanoparticle, Nanopartícula, Pontage fissure, Crack bridging, Ponteado fisura, Propagation fissure, Crack propagation, Propagación fisura, Rupture matrice, Matrix fracture, Ruptura matriz, Résistance rupture, Rupture strength, Resistencia ruptura, Ténacité, Fracture toughness, Tenacidad, Dental nanocomposites, Interface engineering, and Toughening mechanisms

The fracture toughness of dental nanocomposites fabricated by various methods of mixing, silanization, and loadings of nanoparticles had been characterized using fatigue-precracked compact-tension specimens. The fracture mechanisms near the crack tip were characterized using atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The near-tip fracture processes in the nanocomposties were identified to involve several sequences of fracture events, including: (1) particle bridging, (2) debonding at the poles of particle/matrix interface, and (3) crack deflection around the particles. Analytical and finite-element methods were utilized to model the observed sequences of fracture events to identify the source of fracture toughness in the dental nanocomposites. Theoretical results indicated that silanization and nanoparticle loadings improved the fracture toughness of dental nanocomposites by a factor of 2-3 through a combination of enhanced interface toughness by silanization, crack deflection, as well as crack bridging. A further increase in the fracture toughness of the nanocomposites can be achieved by increasing the fracture toughness of the matrix, nanofilled particles, or the interface.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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 biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Vertebres: systeme osteoarticulaire, muscle strie, Vertebrates: osteoarticular system, musculoskeletal system, Squelette et articulations, Skeleton and joints, Sciences medicales, Medical sciences, Radiotherapie. Traitement instrumental. Physiotherapie. Reeducation. Readaptation, orthophonie, crenotherapie. Traitement dietetique et traitements divers (generalites), Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects), Technologie. Biomatériaux. Equipements. Matériel. Appareillage, Technology. Biomaterials. Equipments. Material. Instrumentation, Biomatériau, Biomaterial, Collagène, Collagen, Colágeno, Délaminage, Delamination, Delaminación, Effet fermeture fissure, Crack closure effect, Efecto ciere fisura, Endommagement, Damaging, Deterioración, Essai mécanique, Mechanical test, Ensayo mecánico, Essai normalisé, Standard test, Ensayo normalizado, Etude expérimentale, Experimental study, Estudio experimental, Fissure, Crack, Fisura, Homme, Human, Hombre, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Microstructure, Microestructura, Norme essai, Test standard, Norma ensayo, Os cortical, Cortical bone, Hueso cortical, Ostéoporose, Osteoporosis, Photographie rapide, High speed photography, Fotografía rápida, Photographie ultrarapide, Ultrahigh speed photography, Fotografía ultrarrápida, Polymère, Polymer, Polímero, Propriété mécanique, Mechanical properties, Propiedad mecánica, Relation contrainte déformation, Stress strain relation, Relación tensión deformación, Rupture, Ruptura, Système ostéoarticulaire pathologie, Diseases of the osteoarticular system, Sistema osteoarticular patología, Système ostéoarticulaire, Osteoarticular system, Sistema osteoarticular, Temps réel, Real time, Tiempo real, Trabéculum, Trabecular Meshwork, Trabéculo, Fracture, High-speed photography, Microdamage, Stress-whitening, and Trabecular bone

Mechanical testing of trabecular bone is mainly motivated by the huge impact of osteoporosis in post-menopausal women and the aged in society in terms of social and health care costs. Trabecular bone loss and impairment of its mechanical properties reduce bone strength and increase fracture risk, especially in vertebrae. It is generally accepted that in addition to bone mineral density, microarchitecture and material properties of bone also play important roles for bone strength and fracture risk. In order to overcome the limitations of standard mechanical tests delivering merely integral information about complicated samples, experiments were designed for step-wise mechanical testing with concurrent imaging of trabecular and cortical bone. In this communication we present an approach for real-time imaging of trabecular bone during compression using high-speed photography and investigate the hypothesis whether the whitening of deformed trabeculae is due to microdamage. Experiments on human trabecular bone samples from a healthy male donor revealed that failure of such samples is highly localized in fracture bands. Moreover, strongly deformed trabeculae were seen to whiten, an effect similar to stress whitening in polymers. Scanning Electron Microscopy of the same regions of interest revealed that whitened trabeculae were strongly damaged by microscopic cracks and mostly failed in delamination. Higher resolution images uncovered mineralized collagen fibrils spanning the cracks. The whitening partially faded after unloading of the samples, presumably due to partial crack closure. Overall, high-speed photography enables microdamage detection in real-time during a mechanical test and provides a correlation to recorded stress strain curves.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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...), Acier allié, Alloy steel, Acero aliado, Acier ferritique, Ferritic steel, Acero ferrítico, Amorçage fissure, Crack initiation, Iniciación grieta, Assemblage bout à bout, Butt joint, Junta plana, Assemblage mécanique, Mechanical joint, Ensamblaje mecánico, Assemblage soudé, Welded joint, Ensamblaje soldado, Centrale électrique, Electric power plant, Central eléctrica, Ductilité, Ductility, Ductilidad, Eprouvette essai, Test bar, Probeta ensayo, Essai rupture, Breaking test, Ensayo ruptura, Forme en T, T shape, Forma de una T, Haute température, High temperature, Alta temperatura, Intégrité structure, Structure integrity, Integridad estructura, Métal, Metal, Propagation fissure, Crack propagation, Propagación fisura, Propriété thermomécanique, Thermomechanical properties, Propriedad termomecánica, Raccord tuyauterie, Pipe connection, Unión tubería, Rupture fluage, Creep fracture, Ruptura fluencia, Résistance rupture, Rupture strength, Resistencia ruptura, Temps rupture, Break up time, Tiempo ruptura, Creep crack growth, Failure assessment diagram, Steels, and Welds metals

High temperature deformation and crack resistance of low alloy ferritic grade P22 steel weldments applied in power plants are reported. The creep crack initiation (CCI) and creep crack growth (CCG) data were determined using compact type (C(T)) and C-Shape (CS(T)) fracture mechanics specimens at 550 °C. The deformation and crack growth behaviour of similar weldment zones and significance of CCI and CCG in defect assessment of components were addressed. The weldments with industrially relevant properties were produced in butt welded pipe joint from which test specimens are sampled. The studied material covers a spectrum of microstructures and ductility over the weldment zones to give representative for a welded component. The emphasis is placed on the measurement and particularly analysis of crack initiation for failure assessment in P22 steel weldments. The particular importance of construction of isochronous curves for time dependent failure assessment diagram (TDFAD) method is reported. It is aimed to contribute to establishing guidelines for acceptable methodologies for testing, analysis and assessment of welded components using TDFAD for high temperature service.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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 biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Radiotherapie. Traitement instrumental. Physiotherapie. Reeducation. Readaptation, orthophonie, crenotherapie. Traitement dietetique et traitements divers (generalites), Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects), Maladies du système ostéoarticulaire. Traitement orthopédique, Diseases of the osteoarticular system. Orthopedic treatment, Technologie. Biomatériaux. Equipements. Matériel. Appareillage, Technology. Biomaterials. Equipments. Material. Instrumentation, Amorçage fissure, Crack initiation, Iniciación grieta, Biocompatibilité, Biocompatibility, Biocompatibilidad, Biomatériau, Biomaterial, Cavité, Cavity, Cavidad, Chirurgie orthopédique, Orthopedic surgery, Cirugía ortopédica, Effet composition, Composition effect, Efecto composición, Endommagement, Damaging, Deterioración, Energie rupture, Fracture energy, Energía ruptura, Extrémité fissure, Crack tip, Extremidad fisura, Fractographie, Fractography, Fractografía, Matériau ductile, Ductile material, Material dúctil, Microscopie optique, Optical microscopy, Microscopía óptica, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Mélange, Mixture, Mezcla, Polymère, Polymer, Polímero, Propagation fissure, Crack propagation, Propagación fisura, Restitution énergie, Energy release, Restitución energía, Rupture fragile, Brittle fracture, Ruptura frágil, Résistance rupture, Rupture strength, Resistencia ruptura, Surface rupture, Fracture surface, Superficie ruptura, Bioabsorbable, Fracture toughness, Polymer blend, and Toughening mechanism

Poly(L-lactide) (PLLA) has actively been used as a biomaterial for resorbable bone fixation devices for use in orthopedic and oral surgeries. Recently, in order to improve the fracture properties of brittle PLLA, polymer blends of PLLA and a ductile bioabsorbable polymer, poly(ε-caprolactone) (PCL), have been developed. The aim of the present study is to elucidate details of the fracture behavior and toughening mechanisms of PLLA/PCL blends. PLLA/PCL blends with different PCL contents were developed, and the critical energy release rate at crack initiation, Gin, was then measured to assess the effect of PCL content. It was shown that Gin is dramatically improved by blending PCL with PLLA, and the maximum 51% of increase of Gin is acheived with 5 wt% of PCL. Polarizing optical microscopy (POM) and scanning electron microscopy (SEM) of crack growth behavior were also performed to characterize the fracture mechanism. PLLA/PCL showed multiple craze formation in the crack-tip region, and elongated fibrils and voids construct the crazes. SEM of fracture surface also indicated that stretched fibril structures are formed on the surface as a result of elongation of PCL spherulites under high tensile stress condition in the crack-tip region. Thus, these damage formations are considered to be the primary energy dissipation mechanisms that resulted in the improvement of fracture energy.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Elasticité statique (thermoélasticité...), Static elasticity (thermoelasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Sciences appliquees, Applied sciences, Genie mecanique. Construction mecanique, Mechanical engineering. Machine design, Constructions métalliques, Steel design, Réservoirs métalliques et enceintes sous pression; chaudronnerie, Steel tanks and pressure vessels; boiler manufacturing, Tuyauteries, vannes, robinetteries, Pipings, valves, fittings, Analyse structurale, Structural analysis, Análisis estructural, Assemblage soudé, Welded joint, Ensamblaje soldado, Canalisation, Pipe, Canalización, Conception machine, Machine design, Concepción máquina, Conduite courbe, Curved pipe, Conducto curvado, Contrainte résiduelle, Residual stress, Tensión residual, Coude tuyau, Pipe bend, Codo tubo, Durabilité, Durability, Durabilidad, Durée vie, Lifetime, Tiempo vida, Effet dimensionnel, Size effect, Efecto dimensional, Eprouvette essai, Test bar, Probeta ensayo, Essai fluage, Creep test, Prueba arrastre, Essai traction, Tension test, Ensayo tracción, Haute température, High temperature, Alta temperatura, Maintenance, Mantenimiento, Mesure contrainte, Stress measurement, Mesure température, Temperature measurement, Medida temperatura, Modélisation, Modeling, Modelización, Monitorage, Monitoring, Monitoreo, Métallographie, Metallography, Metalografía, Propagation fissure, Crack propagation, Propagación fisura, Propriété thermomécanique, Thermomechanical properties, Propriedad termomecánica, Rayon X, X ray, Rayos X, Rupture fluage, Creep fracture, Ruptura fluencia, Récipient sous pression, Pressure vessel, Recipiente bajo presión, Régime permanent, Steady state, Régimen permanente, Résistance mécanique, Strength, Resistencia mecánica, Tuyauterie, Piping, Cañería, Vapeur eau, Water vapor, Vapor agua, Creep crack growth, Creep damage assessment, Feature test, Residual stresses, Weld strength, and Weldon

A reliable maintenance and service of energy generation plants would be impossible without the professional designing, manufacturing and monitoring of welded joints. The lifetime assessment factors of welded components as implemented in the design codes must be updated accounting for the modern materials and the advanced steam parameters used in the piping construction [Weld Strength for high temperature components design and operation (WELDON). European Project No. GRD2-2000-30363, Gampe U, Seliger P, Creep crack growth testing of P91 and P22 pipe bends. Int J Pressure Vessels Piping 2001 ;78:859-64, INTEGRITY of repair welds in high temperature plants operating under steady and cyclic loading conditions. European Project No. G5RD-CT-1999-00118]. Within the EU 5th Framework RTD project 'WELDON' tests at high temperatures are performed on component-like feature test specimens like welded pipes and large tensiles in addition to laboratory specimens to study the geometry and size effects on the damage evaluation methodology. The circumferential welds of the pipes are subjected simultaneously to internal pressure and an axial load. The large tensile specimens manufactured from the welded pipes are subjected to uniaxial loading. These components are made from steel grade P22 and P91 and are equipped with gages for on-line monitoring of temperatures, deformations and strains. Residual stresses are measured on these components in as welded and after post-weld heat treatment (PWHT) conditions and are monitored during creep testing with interruptions and after failure. X-ray and hole drilling techniques are employed in these measurements. These data will be used to validate the FE modelling of residual stresses and damage assessment. The results obtained from long time creep tests, metallographic investigations of damage development in the different zones of the weldment and residual stress measurements are presented in this paper.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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...), Aérospatiale, Aerospace, Aeroespacial, Chevauchement, Overlap, Imbricación, Couplage mode, Mode coupling, Acoplamiento modo, Durabilité, Durability, Durabilidad, Durée vie, Lifetime, Tiempo vida, Etude expérimentale, Experimental study, Estudio experimental, Extrémité fissure, Crack tip, Extremidad fisura, Facteur intensité contrainte, Stress intensity factor, Factor intensidad tensión, Fatigue, Fatiga, Fissure fatigue, Fatigue crack, Fisura fatiga, Joint recouvrement, Lap joint, Junta recubierta, Microscope optique, Optical microscope, Microscopio óptico, Relation contrainte déformation, Stress strain relation, Relación tensión deformación, Rupture, Ruptura, Soudage friction malaxage, Friction stir welding, Soudage friction, Friction welding, Soldeo por fricción, FSW, Failure mechanism map, Mixed mode, and Overlap joints

The aim of this work is the characterization of the fatigue behaviour of AA2024-T3 friction stir welded overlap joints produced at German Aerospace Center (DLR) of Cologne (D). In these joints, two crack-like unwelded zones are present at overlap ends. The stress intensity factor at the crack tip and the fatigue crack path have been studied using the FE code Franc2d and the lifetime has been estimated by integrating the material propagation law with the software AFgrow, in which the stress intensity factor calculated with Franc2d was introduced. The numerical results predict lifetimes shorter than the experiments. This fact is attributed to an initial propagation in shear mode for a short distance, which was indeed observed with an optical microscope and it is predicted by mixed mode failure mechanism map.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Elasticité statique (thermoélasticité...), Static elasticity (thermoelasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Radiotherapie. Traitement instrumental. Physiotherapie. Reeducation. Readaptation, orthophonie, crenotherapie. Traitement dietetique et traitements divers (generalites), Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects), Technologie. Biomatériaux. Equipements. Matériel. Appareillage, Technology. Biomaterials. Equipments. Material. Instrumentation, Alliage Ti90Al6V4, Alloy-Ti90Al6V4, Apatite hydroxylée, Hydroxyapatite, Hidroxiapatito, Biomatériau, Biomaterial, Calcium phosphate, Calcio fosfato, Coefficient dilatation thermique, Thermal expansion coefficient, Coeficiente dilatación térmica, Contrainte cisaillement, Shear stress, Tensión cizallamiento, Contrainte résiduelle, Residual stress, Tensión residual, Durabilité, Durability, Durabilidad, Homme, Human, Hombre, Implant, Implante, Long terme, Long term, Largo plazo, Matériau endommagé, Damaged material, Material dañado, Procédé sol gel, Sol gel process, Procedimiento sol gel, Propriété critique, Critical property, Propiedad crítica, Prothèse, Prosthesis, Prótesis, Revêtement métallique, Metal coating, Revestimiento metálico, Résistance cisaillement, Shear strength, Resistencia cizallamiento, Résistance mécanique, Strength, Resistencia mecánica, Transfert par cisaillement, Shear lag, Transferencia cizallamiento, Bioceramic coating, Fluoridated hydroxyapatite, and Sol-gel

Interfacial shear strength is one of the critical properties in bioceramic coatings on metal implants because it directly affects the success of implantation and long-term stability. In this study, shear strain lag method was employed to evaluate the interfacial shear strength of sol-gel derived fluoridated hydroxyapatite (FHA) coatings on Ti6A14V substrates. The residual stresses were measured using the wafer curvature method. The resultant interfacial shear strength increased from pure HA's ∼393-459 MPa as fluorine was increased to 1.96 at% and further increased to ∼572 MPa as fluorine increased to 3.29 at%. The residual stresses in the coating also decreased from pure HA's ∼273-190 MPa and further to ∼137 MPa as fluorine composition in the coating increased. The reduction in the residual stress mainly comes from the reduction in the difference in coefficient of thermal expansion between the coating and the titanium alloy substrate.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Elasticité statique (thermoélasticité...), Static elasticity (thermoelasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Méthodes de mesure et d'essai, Measurement and testing methods, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Propriétés mécaniques et acoustiques de l'état condensé, Mechanical and acoustical properties of condensed matter, Propriétés mécaniques des solides, Mechanical properties of solids, Fluage, Creep, Acier haute résistance, High strength steel, Acero alta resistencia, Amorçage fissure, Crack initiation, Iniciación grieta, Assemblage soudé, Welded joint, Ensamblaje soldado, Contrainte résiduelle, Residual stress, Tensión residual, Endommagement, Damaging, Deterioración, Essai fluage, Creep test, Prueba arrastre, Essai matériau, Material testing, Control material, Extrémité fissure, Crack tip, Extremidad fisura, Fissure fatigue, Fatigue crack, Fisura fatiga, Fluage, Creep, Fluencia, Haute température, High temperature, Alta temperatura, Mesure contrainte, Stress measurement, Modélisation, Modeling, Modelización, Propagation fissure, Crack propagation, Propagación fisura, Relaxation contrainte, Stress relaxation, Relajación tensión, Rupture fluage, Creep fracture, Ruptura fluencia, Zone thermiquement affectée, Heat affected zone, Zona termoafectada, Codes of Practice, Fatigue, Fracture mechanics, HAZ, Standards, VAMAS, Weldments, and Welds

At present there lacks a unified approach in understanding the mechanistic role of weldments cracking in fracture mechanics specimens at elevated temperatures. The effects of residual stress, the development and crack tip damage due to it and the subsequent creep relaxation at high temperatures can be evaluated using relevant test data, numerical modelling and residual stress measurements. These problem areas are considered in this paper and discussed in context under the newly formed collaborative international effort in the Versailles Agreement of Materials and Standards committee, VAMAS TWA31. The plans for this collaborative effort are to evaluate tests at elevated temperatures in a number of high strength steels and also model and measure weldments containing residual stresses. The aim of the four year programme will be to make recommendations and establish pre-standardisation methods for testing, measuring and analysing creep crack initiation (CCI), creep crack growth (CCG), and low frequency creep fatigue crack growth (CFCG) (where creep dominates) characteristics in weldments containing residual stress. The fracture mechanics geometries that will be considered have already been validated in the previous TWA25 collaboration [VAMAS TWA25, Draft Code of Practice, 'Creep/ fatigue Crack Growth in Components', VAMAS document. Nikbin K, editor. May 2005] for testing of parent material. Examples of testing and analysis techniques are presented in this paper to highlight the future objectives for this work.

Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, 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, Inélasticité (thermoplasticité, viscoplasticité...), Inelasticity (thermoplasticity, viscoplasticity...), Mécanique de la rupture (fissure, fatigue, endommagement...), Fracture mechanics (crack, fatigue, damage...), Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Propriétés mécaniques et acoustiques de l'état condensé, Mechanical and acoustical properties of condensed matter, Propriétés mécaniques des solides, Mechanical properties of solids, Fluage, Creep, Assemblage soudé, Welded joint, Ensamblaje soldado, Durabilité, Durability, Durabilidad, Effet dimensionnel, Size effect, Efecto dimensional, Elastoplasticité, Elastoplasticity, Elastoplasticidad, Endommagement, Damaging, Deterioración, Extrémité fissure, Crack tip, Extremidad fisura, Fluage, Creep, Fluencia, Grosseur grain, Grain size, Grosor grano, Inélasticité, Inelasticity, Inelasticidad, Microstructure, Microestructura, Propagation fissure, Crack propagation, Propagación fisura, Propriété mécanique, Mechanical properties, Propiedad mecánica, Rupture fluage, Creep fracture, Ruptura fluencia, Vieillissement, Ageing, Envejecimiento, C* parameter, Ct parameter, Load line displacement rate dδ/dt, Q* concept, and Weld component

The driving force for creep crack growth is dominated by local elastic-plastic stress in the creep damage zone around a crack tip, temperature and microstructure. In previous work, C*, Ct, load line displacement rate dδ/dt and Q* parameters have been proposed as formulations of creep crack growth rate (CCGR). Furthermore, using parameters mentioned above, the construction of the algorithm of predictive law for creep crack growth life is necessary for life assessment procedures. The aim of this paper is to identify the effects of component size, geometry, microstructure, aging and weldment on the embrittling behavior of creep crack growth and incorporate these effects in a predictive law, using the Q* parameter. It was found that for specimen size (width and thickness) and of material softening due to aging the values of the activation energy were the same whereas for grain size change and structural brittleness, which affected crack tip multi-axial stress state the values for the activation energy for CCGR differ.