Download or read book Texturation de surface par LASER femtoseconde en r gime ElastoHydroDynamique et limite written by François Pierre Ninove and published by . This book was released on 2011 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les émissions de polluants dans l’atmosphère représentent l’un des objectifs majeurs à l'heure actuelle. Dans le domaine automobile, la réduction des émissions de CO2 repose en partie sur l’amélioration du rendement moteur. Pour ce faire, ces travaux de thèse sur la texturation de surface à micro et nano échelle proposent de diminuer les pertes par frottements dans les moteurs thermiques alternatifs à combustion interne. Le poste moteur retenu dans cette thèse est le segment/piston/chemise car près de 40 % des pertes par frottement y sont générées. On s’intéresse à la texturation par LASER femtoseconde de cavités sur la surface du segment coup de feu. Le comportement tribologique de surfaces texturées est étudié en régime ElastoHydroDynamique (EHD) et Limite. En régime EHD, la capacité de formation d’un film lubrifiant et le contrôle du frottement en surface texturée indique un comportement tribologique dépendant du couplage entre les paramètres expérimentaux - cinématique des surfaces, pression de contact, taux de rétention en huile et temps de résidence des textures dans le contact et les paramètres géométriques - diamètre, profondeur, densité de textures. En régime Limite, l’influence des textures sur le comportement tribologique a permis de confirmer l’hypothèse sur le rôle de piégeage des débris par les cavités et de mettre en évidence des configurations de réseaux réduisant le coefficient de frottement pour des profondeurs faibles.

Download or read book Precision Assembly Technologies and Systems written by Svetan Ratchev and published by Springer. This book was released on 2014-11-13 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed post-proceedings of the 7th IFIP WG 5.5 International Precision Assembly Seminar, IPAS 2014, held in Chamonix, France, in February 2014. The 20 revised full papers were carefully reviewed and selected from numerous submissions. The papers cover the following topics: micro-assembly processes and systems ranging from desktop factory automation and packaging of MEMS to self-assembly processes and platforms; handling and manipulation, including flexible gripper systems, fixturing and high precision actuators; tolerance management and error-compensation techniques applied at different scales of precision assembly; metrology and quality control; intelligent assembly control; process selection, modelling and planning.

Download or read book Micro texturation de surface du PEEK par laser femtoseconde written by Sabrina Hammouti and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Au cours des dernières années, l'élaboration de surfaces fonctionnelles par voie chimique et/ou topographique a connu un intérêt croissant. Des avancées significatives ont été réalisées pour l'optimisation des propriétés de surface, notamment tribologiques, via l'introduction de traitement visant à structurer à l'échelle nano- et micrométrique la surface de certains composants mécaniques. Différentes approches, chimiques, mécaniques ou énergétiques, peuvent être employées pour l'amélioration ou la maîtrise du frottement et de l'usure, néanmoins le traitement de surface par laser femtoseconde se distingue comme un des meilleurs procédés d'ablation, capable dans certaines conditions de générer des morphologies de surface auto-organisées périodiques, parfois multi-échelles, et appelées ripples. Cette technique appelée Laser Surface Texturing (LST), désormais couramment utilisée en tribologie et applicable à une grande variété de matériaux, présente de nombreux avantages parmi lesquels peuvent être mentionnés les vitesses de texturation atteintes ainsi que la qualité des structures de surface obtenues. De nombreux domaines ont actuellement recours à la texturation de surface par laser comme voie d'amélioration des propriétés tribologiques, comme l'automobile, et d'autres dont la filière du biomédical incarnent progressivement un nouveau champ d'expérimentations. Récemment, une nouvelle génération de prothèses tout en polymère poly(éther éther cétone) (PEEK) a vu le jour, suscitant un intérêt pour des études tribologiques. Ainsi, la texturation de surface par laser femtoseconde du PEEK comme matériau biomédical, en vue d'améliorer ses performances tribologiques, constitue le contexte général de ce travail de thèse. Cette étude traite d'une part, à l'échelle d’un impact laser, du phénomène d'interaction laser-PEEK en mode ultrabref et d'autre part, à l'échelle d’un contact mécanique, de l'optimisation d'une texturation de surface pour la maîtrise du frottement et la réduction de l'usure d'un couple PEEK/PEEK.

Download or read book Rheology and Elastohydrodynamic Lubrication written by B.O. Jacobson and published by Elsevier. This book was released on 1991-07-24 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a thorough overview on recent developments in lubricant rheology, elastohydrodynamic lubrication and the effects of surface roughness and particulate contamination in the lubricant on the overall behaviour of a heavily loaded lubricated contact. One of the aims of the book is to make clear to the reader that a Newtonian model for the lubricant behaviour does not have enough degrees of freedom to be able to describe the friction - traction behaviour of heavily loaded lubricated contacts or the oil film build-up and collapse under surface asperities for rough surfaces. The book contains quite a lot of experimental data of lubricants at high pressures, both solidification pressures, compressibilities and shear strength increase coefficients, which make it possible to estimate the friction and power loss in heavily loaded lubricated contacts for different pressures, temperatures, sliding speeds, and lubricant types. This is the first time that data of this type has been included in a textbook and it is hoped that the questions highlighted will serve to initiate and guide future research in this field.

Download or read book Friction Wear Lubrication written by Kenneth C Ludema and published by CRC Press. This book was released on 2018-09-14 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of a bestseller, this book introduces tribology in a way that builds students’ knowledge and understanding. It includes expanded information on topics such as surface characterization as well as recent advances in the field. The book provides additional descriptions of common testing methods, including diagrams and surface texturing for enhanced lubrication, and more information on rolling element bearings. It also explores surface profile characterization and elastic plastic contact mechanics including wavy surface contact, rough surface contact models, friction and wear plowing models, and thermodynamic analysis of friction.

Download or read book Physical Properties of Amorphous Materials written by David Adler and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Institute for Amorphous Studies was founded in 1982 as the international center for the investigation of amorphous mate rials. It has since played an important role in promoting the und er standing of disordered matter in general. An Institute lecture series on "Fundamentals of Amorphous Materials and Devices" was held during 1982-83 with distinguished speakers from universities and industry. These events were free and open to the public ,and were attended by many representatives of the scientific community. The lectures themselves were highly successful inasmuch as they provided not only formal instruction but also an opportunity for vigorous and stimulating debate. That last element could not be captured within the pages of a book I but the lectures concentrated on the latest advances in the field I which is why their essential contents are he re reproduced in collective form. Together they constitute an interdisciplinary status report of the field. The speakers brought many different viewpoints and a variety of back ground experiences io bear on the problems involved I but though language and conventions vary I the essential unity of the concerns is very clear I as indeed are the ultimate benefits of the many-sided approach.

Download or read book Thinning Films and Tribological Interfaces written by D. Dowson and published by Elsevier. This book was released on 2000-09-01 with total page 857 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection of fully peer-reviewed papers were presented at the 26th Leeds-Lyon Tribology Symposium which was held in Leeds, UK, 14-17 September, 1999. The Leeds-Lyon Symposia on Tribology were launched in 1974, and the large number of references to original work published in the Proceedings over many years confirms the quality of the published papers. It also indicates that the volumes have served their purpose and become a recognised feature of the tribological literature. This year's title is 'Thinning Films and Tribological Interfaces', and the papers cover practical applications of tribological solutions in a wide range of situations. The evolution of a full peer review process has been evident for a number of years. An important feature of the Leeds-Lyon Symposia is the presentation of current research findings. This remains an essential feature of the meetings, but for the 26th Symposium authors were invited to submit their papers for review a few weeks in advance of the Symposium. This provided an opportunity to discuss recommendations for modifications with the authors.