Download or read book Fatigue de composites matrice m tallique base titane renfort unidirectionnel de fibres SiC written by Nicolas Legrand and published by . This book was released on 1997 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ce travail a essayé de comprendre l'origine physique de la rupture en fatigue à haute température des composites à matrice métallique SCS6/TA6V, SM1140+/Ti6242 et SCS6/Ti6242. Le comportement en fatigue du matériau a été étudié selon deux orientations : longitudinale (axe de chargement parallèle à l'axe des fibres) et transversale (axe de sollicitation perpendiculaire à l'axe des fibres). En fatigue longitudinale, effectuée à 450 et 550°C sur le SCS6/TA6V, trois processus majeurs d'endommagement ont été identifiés : le report de charge global de la matrice aux fibres lié à son adoucissement cyclique, la dégradation locale des interfaces au droit des ruptures de fibres et la dégradation des propriétés à rupture du renfort par l'environnement. Les cinétiques d'endommagement de ces différents mécanismes ont pu être évaluées grâce à des observations et à l'émission acoustique. Un modèle micromécanique, prenant en compte le comportement statistique des fibres, a alors permis de confirmer et de quantifier l'influence de ces trois mécanismes d'endommagement sur la rupture en fatigue de composite. Il a ainsi été montré qu'à des niveaux de sollicitation suffisamment élevés (contrainte supérieure à 1000MPa), la dégradation locale des interfaces au droit des ruptures de fibres peut conditionner à elle seule la durée de vie en fatigue du composite. Enfin, en se basant sur les résultats expérimentaux d'émission acoustique, le modèle a permis, au moins semi quantitativement, d'être prédictif en cinétique d'endommagement et en rupture.
Download or read book Fatigue in SiC Fibre Reinforced Titanium Metal Matrix Composites written by Matthew Nicholas Dear and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comportement en fatigue anisotherme des composites unidirectionnels matrice titane renforc e par des fibres de carbure de silicium written by Faten Bourbita and published by . This book was released on 2011 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'objectif de cette étude est de déterminer la tenue du composite SCS-6/Ti6242, alliage de titane avec un renfort unidirectionnel de fibres SiC, pour des applications à température moyenne notamment pour des pièces critiques de moteurs aéronautiques, sous sollicitations thermiques et mécaniques combinées. Les conditions de chargement en service sont simulées en laboratoire par des essais de fatigue mécano-thermique, réalisés dans la plage de températures 100°C - 450°C, en contrainte imposée, sous un rapport de charge nul. Les observations des faciès de rupture réalisées par microscopie optique et électronique à balayage ont montré l'existence de deux mécanismes d'endommagement : la rupture des fibres comme en rupture monotone et la fissuration de la matrice par fatigue. Une analyse par éléments finis a été mise en place pour étudier le comportement mécanique du composite, à partir d'une méthode d'homogénéisation et du comportement de ses constituants. Les calculs montrent l'importance de la redistribution des contraintes entre les fibres et la matrice. Les résultats sont utilisés pour expliquer les mécanismes d'endommagement observés et les conséquences sur la prévision des durées de vie en fatigue anisotherme. La croissance de fissures longues en conditions anisotherme et isotherme a fait l'objet d'une étude expérimentale. Une analyse de mécanique de la rupture recourant à une méthode de zone cohésive a permis de rationaliser les vitesses fissuration observées.
Download or read book Fracture and Fatigue of SiC Fibre Reinforced Titanium Matrix Laminated Composites written by Figen Kaya and published by . This book was released on 1999 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Damage Evolution and Degradation of Mechanical Properties in Silicon Carbide SiC Fiber Reinforced Titanium Matrix Composites written by SM. Jeng and published by . This book was released on 1996 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue damage accumulation and failure modes of several unidirectional and angle-ply SCS-6 fiber-reinforced titanium matrix composites are reviewed. The fatigue damage characteristics of the notched and unnotched composites were classified using several schematic diagrams based upon the constituent's properties and loading conditions. Quantitative relationships between the microstructural damage and stiffness reduction were also established. A shear-lag model incorporating a damage function (which involved the cracking density and length, fiber/matrix frictional stress, and debonding length) was also used to predict residual stiffness of the composites.
Download or read book Analysis of Thermomechanical Fatigue of Unidirectional Titanium Metal Matrix Composites written by YA. Bahei-El-Din and published by . This book was released on 1993 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermomechanical fatigue (TMF) data have been generated for a Ti-15V-3Cr-3Al-3Sn (Ti-15-3) material reinforced with SCS-6 silicon carbide fibers for both in-phase and out-of-phase testing. Significant differences in failure mechanisms and fatigue life are noted for the in-phase and out-of-phase testing. The purpose of the research reported in this paper is to apply a micromechanics model to analysis of the data. The analysis predicts the stresses in the fiber and in the matrix material during the thermal and mechanical cycling by calculating both the thermal and mechanical stresses and their time-dependent behavior. The rate-dependent behavior of the matrix was characterized and was used to calculate the constituent stresses in the composite. The predicted 0° fiber stress range was used to explain the composite failure. It was found that for a given condition, temperature, loading frequency, and time at temperature, the 0° fiber stress range may control the fatigue life of the unidirectional composite.
Download or read book Fatigue Behavior of Silicon Carbide Reinforced Titanium Composites written by RT. Bhatt and published by . This book was released on 1981 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The low cycle axial fatigue properties of 25 and 44-fiber volume percent SiC/Ti(6Al-4V) composites were measured at room temperature and at 650°C. At room temperature, the S-N curves for the composites showed no anticipated improvement over bulk matrix behavior. Although axial and transverse tensile strength results suggest a degradation in silicon-carbide fiber strength during composite fabrication, it appears that the poor fatigue life of the composites was caused by a reduced fatigue resistance of the reinforced Ti(6Al-4V) matrix. Microstructural studies indicate that the reduced matrix behavior was due, in part, to the presence of flawed and fractured fibers created near the specimen surfaces by preparation techniques. Another possible contributing factor is the large residual tensile stresses that can exist in fiber-reinforced matrices. These effects as well as the effects of fatigue testing at high temperature are discussed.
Download or read book Fatigue Damage Mechanisms of a Continuous Silicon Carbide SiC Fiber Reinforced Titanium Matrix Composite written by Ochang Jin and published by . This book was released on 1998 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fracture and Fatigue of Selectively Continuous Silicon Carbide Fibre Reinforced Titanium Metal Matrix Composites for Advanced Aerospace Applications written by Supachai Fakpiam and published by . This book was released on 2005 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Significance of Environment in Thermal Fatigue of a Unidirectional SCS 6 Ti 24Al 11Nb Metal Matrix Composite written by M. Okazaki and published by . This book was released on 2000 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal Fatigue tests of a Ti-24Al-11Nb matrix composite unidirectionally reinforced with SiC fiber, SCS-6/Ti-24Al-11Nb, have been carried out without external load in air and in vacuum, under various thermal cycling conditions. The following characteristics of the material subjected to thermal fatigue and isothermal exposure were investigated: (i) crack nucleation and the change in density with thermal cycling; (ii) change of the fiber/matrix interface morphology by means of Electron Probe Micro Analyzer and Scanning Electron Microscope; (iii) change of the interfacial shear strength by fiber push-out tests, and (iv) effect of environment on the properties from (i) to (iii). Methodologies are also proposed for the characterization of damage due to thermal fatigue.
Download or read book Etude de la propagation de fissures par fatigue dans les mat riaux composites matrice de titane renforc es par des filaments de B B B4C et SiC written by Panayiotis Soumelidis and published by . This book was released on 1984 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flexoelectricity in Liquid Crystals written by Agnes Buka and published by World Scientific. This book was released on 2013 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.
Download or read book Nonlinear Optical Materials written by Jerome V. Moloney and published by Springer Science & Business Media. This book was released on 1998-08-13 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematical methods play a significant role in the rapidly growing field of nonlinear optical materials. This volume discusses a number of successful or promising contributions. The overall theme of this volume is twofold: (1) the challenges faced in computing and optimizing nonlinear optical material properties; and (2) the exploitation of these properties in important areas of application. These include the design of optical amplifiers and lasers, as well as novel optical switches. Research topics in this volume include how to exploit the magnetooptic effect, how to work with the nonlinear optical response of materials, how to predict laser-induced breakdown in efficient optical devices, and how to handle electron cloud distortion in femtosecond processes.
