Download or read book Contribution la caract risation des mat riaux au comportement visco lastique par m thode ultrasonore written by Nicolas Larcher and published by . This book was released on 2014 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ce travail de thèse se place dans le cadre de la problématique de la caractérisation des matériaux thermo-viscoélastiques en laboratoire avec une application sur les matériaux bitumineux. Actuellement, la caractérisation mécanique de ces matériaux nécessite des essais coûteux autant en termes de temps, que de matériel et de matériau. L’objectif est de proposer une alternative à ces essais par le biais d’un essai de Contrôle Non Destructif (CND) basé sur la mesure des grandeurs caractéristiques de la propagation des ondes ultrasonores. Les matériaux de l’étude, un bitume et deux enrobés bitumineux ont été développés par l’entreprise EIFFAGE Travaux Publics. Les enrobés bitumineux font l’objet d’une étude visant l’optimisation de la structure granulaire des enrobés bitumineux dans le but d’augmenter leurs performances mécaniques. Une attention particulière est portée aux méthodes de détermination des grandeurs caractéristiques de la propagation d’ondes et à la prise en compte de leur dépendance fréquentielle. Les données expérimentales de référence, issues des essais standards de module complexe (G* et E*), sont représentées et interprétées sur la base de différentes représentations : courbes maitresses, plan de Cole – Cole et espace de Black. Ces représentations sont également extrapolées à l’aide d’un modèle rhéologique à spectre continu, le modèle 2S2P1D. La caractérisation de ces matériaux par la méthode ultrasonore repose sur deux aspects : d’une part la détermination de la vitesse de phase et du facteur d’atténuation des ondes de compression et de cisaillement ; d’autre part la détermination des grandeurs mécaniques (G*, E* et v*) par le biais des équations de propagation en 2D dans un milieu élastique ou viscoélastique isotrope. Les résultats obtenus montrent une bonne adéquation entre les données ultrasonores, les mesures mécaniques et les prédictions du modèle rhéologique. Les représentations complexes par séparation des parties réelles et imaginaire montrent l’apport essentiel de l’hypothèse viscoélastique dans l’exploitation des données ultrasonores et la nécessité de la prise en compte des différents mécanismes dissipatifs conduisant l’atténuation des ondes dans un matériau hétérogène viscoélastique.

Download or read book Contribution la caract risation ultrasonore de mat riaux poreux par variation de pression statique written by Stéphane Griffiths and published by . This book was released on 2007 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: La caractérisation par ultrasons de matériaux poreux, fortement utilisés comme absorbants sonore, est généralement bien maîtrisée. Cependant, la caractérisation en transmission de certains matériaux peut se montrer difficile, et, lorsque le phénomène de diffusion intervient, celle-ci s'avère problématique. Pour répondre à cette double problématique, une méthode de caractérisation ultrasonore basée sur la variation de la pression statique du fluide saturant a été développée. La transmission s'en trouve alors accrue à travers le milieu poreux. Elle autorise également théoriquement la séparation des pertes dues à la diffusion et aux effets viscothermiques selon les premières études de Nagy en 1995. Une première thèse sur le sujet, dont les travaux ont été repris dans le cadre de la présente thèse, a montré qu'il est effectivement possible de séparer les pertes par diffusion des pertes viscothermiques. Bien que le modèle de fluide équivalent décrive bien les comportements du coefficient de transmission et de la vitesse en présence de diffusion faible, il n'est plus valide lorsque la diffusion est plus élevée. Il reste cependant possible d'estimer la longueur caractéristique viscothermique. Il n'est donc pas nécessaire, avec cette méthode, de connaître les caractéristiques de la diffusion pour estimer les paramètres acoustiques du matériau. Le second axe de recherche portant sur la caractérisation de matériaux très atténuants, un nouveau système expérimental permettant d'opérer à des pressions plus élevées (jusqu'à 20 bars) a été développé au cours de cette thèse. Il est ainsi apparu que le comportement linéaire décrit par le modèle de fluide équivalent aux basses pressions (jusqu'à 6 bars) n'est plus respecté aux pressions élevées (atteignant 18 bars). Ce comportement varie avec la nature mécanique et résistive du matériau, et les mesures réalisées sont très sensibles aux variations de température. Un modèle analytique basé sur une simplification du modèle de Biot à été utilisé afin de décrire ces phénomènes en tenant compte de ces différentes variables. Les variations des mesures avec la température n'étant pas expliquées par ce modèle, il est supposé que les paramètres mécaniques varient avec elle. Connaissant les paramètres influents aux pressions et fréquences considérées, il est dès lors possible d'estimer par minimisation, sous certaines conditions, certains paramètres acoustiques et mécaniques. L'algorithme de minimisation doit être cependant encore optimisé pour mettre clairement en évidence la dépendance thermique des paramètres mécaniques.

Download or read book CONTRIBUTION A L ETUDE DU COMPORTEMENT DYNAMIQUE ET AU CHOC DES MATERIAUX ET DES STRUCTURES COMPOSITES written by CONG.. DOAN and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE ETUDE PORTE SUR LE PROBLEME DU COMPORTEMENT DYNAMIQUE ET AU CHOC DES MATERIAUX ET DES PLAQUES COMPOSITES DOUEES DE VISCOELASTICITE. LE PREMIER CHAPITRE EST CONSACRE A L'ETUDE DU COMPORTEMENT VISCOELASTIQUE DES MATRICES POLYMERIQUES. NOUS AVONS DEVELOPPE DEUX MODELES RHEOLOGIQUES UTILISANT LE CALCUL FRACTIONNAIRE POUR DECRIRE LE COMPORTEMENT VISCOELASTIQUE D'UNE MATRICE EPOXYDE. LA DEUXIEME PARTIE PRESENTE LA MODELISATION DU COMPORTEMENT VISCOELASTIQUE DES MATERIAUX COMPOSITES. NOUS UTILISONS DES METHODES D'HOMOGENEISATION DU COMPORTEMENT ELASTIQUE EN APPLIQUANT LE PRINCIPE DE CORRESPONDANCE VISCOELASTIQUE-ELASTIQUE. LE TROISIEME CHAPITRE PORTE SUR LE PROBLEME DES VIBRATIONS FORCEES DES PLAQUES COMPOSITES DOUEES DE VISCOELASTICITE. L'EQUATION DE MOUVEMENT DES PLAQUES MULTICOUCHES EST ABORDEE SUIVANT LA METHODE DE LAGRANGE. LE MECANISME DE L'AMORTISSEMENT EST ETUDIE PAR L'APPLICATION DU PRINCIPE DE CORRESPONDANCE VISCOELASTIQUE-ELASTIQUE. LA DERNIERE PARTIE DE THESE CONCERNE L'ANALYSE EXPERIMENTALE DU COMPORTEMENT AU CHOC A FAIBLE VITESSE (MOINS 10 M/S) ET AVEC UN FAIBLE NIVEAU D'ENERGIE D'UN STRATIFIE COMPOSITE VERRE/EPOXYDE. NOUS AVONS ELABORE UNE MACHINE D'ESSAIS ET UNE PROCEDURE EXPERIMENTALE DE CARACTERISATION. AU PLAN THEORIQUE, NOUS UTILISONS L'ANALYSE MODALE ET LA METHODE ITERATIVE POUR PREVOIR LE COMPORTEMENT AU CHOC DE LA PLAQUE ET ETABLISSONS LES CORRELATIONS ENTRE COMPORTEMENT DYNAMIQUE ET COMPORTEMENT AU CHOC DE LA PLAQUE

Download or read book Mechanical Identification of Composites written by A. Vautrin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Properties of UO2 written by J. Belle and published by . This book was released on 1957 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Modeling of Mechanical Systems written by Mohamed Haddar and published by Springer Science & Business Media. This book was released on 2013-03-12 with total page 653 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 5th International Congress on Design and Modeling of Mechanical Systems (CMSM) was held in Djerba, Tunisia on March 25-27, 2013 and followed four previous successful editions, which brought together international experts in the fields of design and modeling of mechanical systems, thus contributing to the exchange of information and skills and leading to a considerable progress in research among the participating teams. The fifth edition of the congress (CMSM ́2013), organized by the Unit of Mechanics, Modeling and Manufacturing (U2MP) of the National School of Engineers of Sfax, Tunisia, the Mechanical Engineering Laboratory (MBL) of the National School of Engineers of Monastir, Tunisia and the Mechanics Laboratory of Sousse (LMS) of the National School of Engineers of Sousse, Tunisia, saw a significant increase of the international participation. This edition brought together nearly 300 attendees who exposed their work on the following topics: mechatronics and robotics, dynamics of mechanical systems, fluid structure interaction and vibroacoustics, modeling and analysis of materials and structures, design and manufacturing of mechanical systems. This book is the proceedings of CMSM ́2013 and contains a careful selection of high quality contributions, which were exposed during various sessions of the congress. The original articles presented here provide an overview of recent research advancements accomplished in the field mechanical engineering.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1988 with total page 1132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the RILEM International Symposium on Bituminous Materials written by Hervé Di Benedetto and published by Springer Nature. This book was released on 2021-09-25 with total page 1806 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume highlights the latest advances, innovations, and applications in bituminous materials and structures and asphalt pavement technology, as presented by leading international researchers and engineers at the RILEM International Symposium on Bituminous Materials (ISBM), held in Lyon, France on December 14-16, 2020. The symposium represents a joint effort of three RILEM Technical Committees from Cluster F: 264-RAP “Asphalt Pavement Recycling”, 272-PIM “Phase and Interphase Behaviour of Bituminous Materials”, and 278-CHA “Crack-Healing of Asphalt Pavement Materials”. It covers a diverse range of topics concerning bituminous materials (bitumen, mastics, mixtures) and road, railway and airport pavement structures, including: recycling, phase and interphase behaviour, cracking and healing, modification and innovative materials, durability and environmental aspects, testing and modelling, multi-scale properties, surface characteristics, structure performance, modelling and design, non-destructive testing, back-analysis, and Life Cycle Assessment. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster new multidisciplinary collaborations.

Download or read book Asphalt Pavements written by Y. Richard Kim and published by CRC Press. This book was released on 2014-11-06 with total page 1966 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asphalt Pavements contains the proceedings of the International Conference on Asphalt Pavements (Raleigh, North Carolina, USA, 1-5 June 2014), and discusses recent advances in theory and practice in asphalt materials and pavements. The contributions cover a wide range of topics:- Environmental protection and socio-economic impacts- Additives and mo

Download or read book Flow Sensing in Air and Water written by Horst Bleckmann and published by Springer Science & Business Media. This book was released on 2014-01-22 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, leading scientists in the fields of sensory biology, neuroscience, physics and engineering explore the basic operational principles and behavioral uses of flow sensing in animals and how they might be applied to engineering applications such as autonomous control of underwater or aerial vehicles. Although humans possess no flow-sensing abilities, countless aquatic (e.g. fish, cephalopods and seals), terrestrial (e.g. crickets and spiders) and aerial (e.g. bats) animals have flow sensing abilities that underlie remarkable behavioral feats. These include the ability to follow silent hydrodynamic trails long after the trailblazer has left the scene, to form hydrodynamic images of their environment in total darkness, and to swim or fly efficiently and effortlessly in the face of destabilizing currents and winds.

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 Bituminous Binders and Mixes written by L. Francken and published by CRC Press. This book was released on 2004-03-01 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the studies presented in this report is the implementation of rational concepts and testing procedures for the design and manufacture of bituminous materials for applications in pavement construction. Practical test procedures are recommended for binder evaluation, mix design and performance assessment of bituminous materials. The three main topics addressed are binder testing, mix design and mechanical testing of mixtures. Each is examined through interlaboratory tests and there is a literary review of existing practices and methods for the production of polymer modified binders, mixture design and the mechanical properties of mixtures.

Download or read book Mechanical Vibration written by William John Palm and published by . This book was released on 2007 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model, analyze, and solve vibration problems, using modern computer tools. Featuring clear explanations, worked examples, applications, and modern computer tools, William Palm's Mechanical Vibration provides a firm foundation in vibratory systems. You'll learn how to apply knowledge of mathematics and science to model and analyze systems ranging from a single degree of freedom to complex systems with two and more degrees of freedom. Separate MATLAB sections at the end of most chapters show how to use the most recent features of this standard engineering tool, in the context of solving vibration problems. The text introduces Simulink where solutions may be difficult to program in MATLAB, such as modeling Coulomb friction effects and simulating systems that contain non-linearities. Ample problems throughout the text provide opportunities to practice identifying, formulating, and solving vibration problems. KEY FEATURES Strong pedagogical approach, including chapter objectives and summaries Extensive worked examples illustrating applications Numerous realistic homework problems Up-to-date MATLAB coverage The first vibration textbook to cover Simulink Self-contained introduction to MATLAB in Appendix A Special section dealing with active vibration control in sports equipment Special sections devoted to obtaining parameter values from experimental data

Download or read book Cities and Their Vital Systems written by Advisory Committee on Technology and Society and published by National Academies Press. This book was released on 1989 with total page 1298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cities and Their Vital Systems asks basic questions about the longevity, utility, and nature of urban infrastructures; analyzes how they grow, interact, and change; and asks how, when, and at what cost they should be replaced. Among the topics discussed are problems arising from increasing air travel and airport congestion; the adequacy of water supplies and waste treatment; the impact of new technologies on construction; urban real estate values; and the field of "telematics," the combination of computers and telecommunications that makes money machines and national newspapers possible.

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.