LES DEGRADATIONS OBSERVEES DANS LES CONTRATS SOUMIS A DES SOLLICITATIONS DE FRETTING APPARAISSENT SOUS DIFFERENTES FORMES EN FONCTION DES CONDITIONS DE SOLLICITATION. FONDEE SUR L'ANALYSE ELASTIQUE DU CONTACT SPHERE-PLAN, CETTE ETUDE A POUR OBJECTIF DE QUANTIFIER LES TROIS ASPECTS QUE SONT : LA CONDITION DE GLISSEMENT, L'AMORCAGE DE FISSURES EN GLISSEMENT PARTIEL ET L'USURE PAR FORMATION DE DEBRIS POUR LES GRANDES AMPLITUDES DE GLISSEMENT. ON MONTRE QUE LA CONDITION DE GLISSEMENT PEUT ETRE DECRITE A PARTIR DE TROIS VARIABLES A, B, C QUI PERMETTENT DE DEFINIR LA TRANSITION ENTRE GLISSEMENT PARTIEL ET GLISSEMENT TOTAL. LA CONDITION D'AMORCAGE A GRAND NOMBRE DE CYCLES, ETUDIEE EN GLISSEMENT PARTIEL, DEPEND DU COMPORTEMENT DU MATERIAU. POUR UN ACIER PRESENTANT UN ECROUISSAGE DU TYPE ISOTROPE (30NCD16), LE CRITERE DE DANG VAN PERMET DE QUANTIFIER LE RISQUE D'AMORCAGE DANS LE CONTACT SI L'ON TIENT COMPTE DU COEFFICIENT DE FROTTEMENT LOCAL DANS L'ANNEAU DE GLISSEMENT ET DE L'EFFET D'ECHELLE. POUR LES ACIERS FORTEMENT ALLIES, FRAGILES (SC6-5-2), IL IMPORTE DE TENIR COMPTE DES MICRO-CARBURES PRESENTS DANS L'ACIER ET D'ASSOCIER LA CONDITION DE FISSURATION A UN SEUIL DE PROPAGATION. L'USURE PAR FORMATION DE DEBRIS EN GRANDS DEBATTEMENTS EST ETUDIEE EN ASSOCIANT LA QUANTITE DE MATIERE USEE A L'ENERGIE INTERFACIALE DISSIPEE. L'ANALYSE GLOBALE EST AFFINEE PAR UNE DESCRIPTION LOCALE DE L'ENERGIE DISSIPEE DANS LE CONTACT. ON INTRODUIT DES COEFFICIENTS ENERGETIQUES D'USURE QUI MONTRENT UNE CINETIQUE DE DEGRADATION DE L'ACIER SC6-5-2 DE 9 A 10 FOIS SUPERIEURE A CELLE DU DEPOT TIN.

This is a collection of papers presented at the 13th International Conference on Aluminum Alloys (ICAA-13), the premier global conference for exchanging emerging knowledge on the structure and properties of aluminum materials. The papers are organized around the topics of the science of aluminum alloy design for a range of market applications; the accurate prediction of material properties; novel aluminum products and processes; and emerging developments in recycling and applications using both monolithic and multi-material solutions.

Surveys the online social habits of American teens and analyzes the role technology and social media plays in their lives, examining common misconceptions about such topics as identity, privacy, danger, and bullying.

Examines the factors which limit human economic and population growth and outlines the steps necessary for achieving a balance between population and production. Bibliogs

This open access book contains a structured collection of the complete solutions of all essential axisymmetric contact problems. Based on a systematic distinction regarding the type of contact, the regime of friction and the contact geometry, a multitude of technically relevant contact problems from mechanical engineering, the automotive industry and medical engineering are discussed. In addition to contact problems between isotropic elastic and viscoelastic media, contact problems between transversal-isotropic elastic materials and functionally graded materials are addressed, too. The optimization of the latter is a focus of current research especially in the fields of actuator technology and biomechanics. The book takes into account adhesive effects which allow access to contact-mechanical questions about micro- and nano-electromechanical systems. Solutions of the contact problems include both the relationships between the macroscopic force, displacement and contact length, as well as the stress and displacement fields at the surface and, if appropriate, within the half-space medium. Solutions are always obtained with the simplest available method - usually with the method of dimensionality reduction (MDR) or approaches which use the solution of the non-adhesive normal contact problem to solve the respective contact problem.

This book reviews the current understanding of the mechanical, chemical and biological processes that are responsible for the degradation of a variety of implant materials. All 18 chapters will be written by internationally renowned experts to address both fundamental and practical aspects of research into the field. Different failure mechanisms such as corrosion, fatigue, and wear will be reviewed, together with experimental techniques for monitoring them, either in vitro or in vivo. Procedures for implant retrieval and analysis will be presented. A variety of biomaterials (stainless steels, titanium and its alloys, nitinol, magnesium alloys, polyethylene, biodegradable polymers, silicone gel, hydrogels, calcium phosphates) and medical devices (orthopedic and dental implants, stents, heart valves, breast implants) will be analyzed in detail. The book will serve as a broad reference source for graduate students and researchers studying biomedicine, corrosion, surface science, and electrochemistry.

Tribocorrosion causes the degradation or alteration of materials through the combined action of corrosion and wear. It limits the performance and life-time of installations, machines and devices with moving parts, and controls certain manufacturing processes such as chemical–mechanical polishing. The effects of tribocorrosion are most pronounced on passive metals which owe their corrosion resistance to a thin protecting oxide film. Most corrosion-resistant engineering alloys belong to this category.This book provides an introduction to the developing field of tribocorrosion and an overview of the latest research. Part one reviews basic notions of corrosion and tribology, before presenting the most recent results on the growth and structure of passive oxide films. Tribocorrosion mechanisms under fretting, sliding and erosion conditions, respectively, are then discussed. Part two focuses on methods for measuring and preventing tribocorrosion. It includes chapters on electrochemical techniques, the design of tribocorrosion test equipment, data evaluation and the optimisation of materials' properties for tribocorrosion systems. Part three presents a selection of tribocorrosion problems in engineering and medicine. Three chapters address the tribocorrosion of medical implants including test methods and clinical implications. Other chapters examine tribocorrosion issues in nuclear power plants, marine environments, automotive cooling circuits, elevated-temperature metal working and chemical–mechanical polishing.With its distinguished editors and international team of expert contributors Tribocorrosion of passive metals and coatings is an invaluable reference tool for engineers and researchers in industry and academia confronted with tribocorrosion problems. - Comprehensively reviews current research on the tribocorrosion of passive metals and coatings, with particular reference to the design of tribocorrosion test equipment, data evaluation and the optimisation of materials' properties for tribocorrosion systems - Chapters discuss tribocorrosion mechanisms under fretting, sliding and erosion conditions before focussing on methods for measuring and preventing tribocorrosion - Includes a comprehensive selection of tribocorrosion problems in engineering and medicine, such as the tribocorrosion of medical implants, and tribocorrosion issues in nuclear power plants, marine environments, automotive cooling circuits and elevated-temperature metal working