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Most friction models for automatic control are targeted for the macro world, and are of questionable value for the motion control of the high precision positioing stages. We published a paper recently in Technishes Messen (TM) on a study of the friction behavior in the moving range of micrometers. It provides info for the development of friction models targeted for the motion control in high precision engineering.
The following is the abstract, and the full paper can be downloaded from http://www.atypon-link.com/OLD/doi/abs/10.1524/teme.2006.73.9.500
ABSTRACT Most friction models for automatic control are targeted for the macro world, and are of questionable value for the motion control of the nanopositioning and nanomeasuring machine (NPM) system. We present the frictional behaviour of some selected materials, coatings, lubricants, and bearings tested under running conditions similar to a NPM system. Continuous change of surface properties results in various friction characteristics, which substantiate the further development of tribological coatings, particularly for vacuum applications. We emphasize the system engineering approach in developing friction models, which combines fundamental knowledge of surface science, materials science, and its applications in design, construction and automatic control.
Presented at the Applied Mechanics Dinner of the 2006 Winter Annual Meeting of ASME, Hilton Chicago Hotel, 9 November 2006.
First and formost, I must acknowledge with gratitude the honour of being selected for the Timoshenko medal for 2006. But since a speech is now expected, I realise that this is not free lunch. If you know a good pub, this would be a good time to slip away.
When I received Virgil Carter's letter informing me that I had been selected, I could not believe it. There must have been a mistake; after all Johnson is a very common name. I am reminded of my first meeting with Bernie Budiansk from Harvard, also a Timoshenko medallist. He asked, "Did you write that book on vibration with Bishop?" "No. That was Dan Johnson"; " Did you edit that British Journal of mechanical sciences?": "No. That was Bill Johnson"; "Who the hell are you!"
Meshfree Particle Methods is a comprehensive and systematic exposition of particle methods, meshfree Galerkin and partition of unity methods, molecular dynamics methods, and multiscale methods. It presents theoretical foundation, numerical algorithms, as well as applications. Since it was published in 2004, the first print has been sold out. The publisher is preparing the second print.
Any materials scientist interested in mechanical behaviour would be aware of the contributions of J.D. Eshelby. With 56 papers, Eshelby revolutionised our understanding of the theory of materials. The problem that I wish to discuss in this page is the elastic stress and strain fields due to an ellipsoidal inclusion/inhomogeneity - a problem that was solved by Eshelby using an elegant thought experiment.
In two papers published in the Proceedings of Royal Society (A) in 1957 and 1959 (Volume 241, p. 376 and Volume 252, p. 561) Eshelby solved the following problem ("with the help of a simple set of imaginary cutting, straining and welding operations"): In his own words,
I have not read the above-mentioned paper, as I have never been able to find it. However it is said to be "a brilliantly insightful paper which was to lay the foundations of modern elasticity." However, I believe it is also noteworthy for being one of the major contributions by a female mechanician prior to the modern era. For a great biography of Sophie Germain, including a fantastic quote from a letter from Carl Gauss on discovering that she was female--and not "Monsieur Le Blanc"--visit this site (from which the above quote, on the impact of her paper, came).
There are no female mechanicians listed on http://en.wikipedia.org/wiki/Mechanicians but I believe it could be argued that Germain deserves a mention!
Companion web site http://micro.stanford.edu ISBN:0-19-852614-8, Hard cover, 304 pages, Nov. 2006, US $74.50.
This book presents a broad collection of models and computational methods - from atomistic to continuum - applied to crystal dislocations. Its purpose is to help students and researchers in computational materials sciences to acquire practical knowledge of relevant simulation methods. Because their behavior spans multiple length and time scales, crystal dislocations present a common ground for an in-depth discussion of a variety of computational approaches, including their relative strengths, weaknesses and inter-connections. The details of the covered methods are presented in the form of "numerical recipes" and illustrated by case studies. A suite of simulation codes and data files is made available on the book's website to help the reader "to learn-by-doing" through solving the exercise problems offered in the book. This book is part of an Oxford Series on Materials Modelling.
Fundamentals of Micromechanics of Solids, Jianmin Qu, Mohammed Cherkaoui
ISBN: 0-471-46451-1, Hardcover, 400 pages, August 2006, US $120.00
PART I: LINEAR MICROMECHANICS AND BASIC CONCEPTS
Chapter 1 INTRODUCTION
Chapter 2 BASIC EQUATIONS OF CONTINUUM MECHANICS
GRIFFITH AA, The phenomena of rupture and flow in solids. Philosophical Transactions of the Royal Society of London, Sereis A, 221:163-198, 1921.
The Eighth International Conference on Fundamentals of Fracture (ICFF VIII) is the successor of the previous seven held at NBS, Gaithersburg (USA, 1983), Gatlinburg (USA, 1985), Irsee (Germany, 1989), Urabandai (Japan, 1993), NIST, Gaithersburg (USA, 1997), Cirencester (UK, 2001), and Nancy (France, 2005). You are warmly invited to participate in ICFF VIII which will be held 3-7 January 2008 in Hong Kong University of Science and Technology, Hong Kong, and in Guangzhou, China. As the previous conferences, ICFF VIII provides an international forum for presentation and discussion of the latest scientific and technological development in fundamentals of fracture. The general theme of ICFF VIII is to cover all aspects of fracture at a fundamental level, including contributions from those working in the disciplines of Continuum Mechanics, Physics, Chemistry, Bioscience, Metallurgy, Ceramics, Polymer Science, etc. You are cordially invited to submit an abstract to join in this memorable event.
