Based on some recent results by Anders Klabring, myself and Jim Barber, showing rigorously that Melan’s theorem only works for a very restricted class of frictional problems, we suggest possible ave
In my blog "Rolling Moment Resistance of Particles on Surfaces," I've talked about this topic/problem a little bit. We are looking for understanding/characterizing of coupling between rolling resistance moment and axial adhesion of particles on surfaces.
I was a little bit surprised in the introduction of this new forum to see mention of elastic and plastic contacts but no specific mention of viscoelastic contacts.
In the era of commercially-available instruments for indentation testing, the examination of viscoelastic contact mechanics, both in the context of polymers and biological tissues, seems to have taken on new life. To a first approximation, for indentation testing in the time domain, the fundamental mechanics has not much advanced beyond a few classic papers of the 1960s: Lee and Radok, J. Appl. Mech. 27 (1960) 438 and Ting TCT, J. Appl. Mech. 88 (1966) 845. However, the implementation of techniques for analysis of experimental data has progressed substantially. With spherical indenters the use of linearly viscoelastic models for characterization of a material creep or relaxation function is straightforward. Recent experimental studies have confirmed this, while more lingering questions remain for sharp contacts including Berkovich pyramidal indenters (most commonly shipped with commercial indenters). Sharp contacts seem to give rise to nonlinearly viscoelastic responses. Other topics of recent interest include frequency-domain measurements and examination of oscillating contacts and adhesion. (Although not mentioned in the listing of KLJ's most-loved topics in contact mechanics, viscoelastic contact has been the subject of several recent KLJ publications!) Although research in viscoelastic contact mechanics has been strong in recent years, perhaps a challenge remains in the dissemination of information and the establishment of approachable experimental techniques for use by non-experts.
In this short note we remark that, at least for the theory of Fuller & Tabor for the adhesive contact of rough random surfaces, fractal surfaces have a limiting zero pull-off force, for all fractal dimensions or amplitudes of roughness. This paradoxical result raises some questions. I ask the iMechanica community for opinions, comparisons of experiments, etc.
If we read Ken Johnson’s Timoshenko medal 2006 speech also posted in iMechanica, the subjects Ken mentions in his brief and humorous speech are:-
These are probably the subjects Ken is most attached to. Some are older (but perhaps not solved, lke corrugation, for which the “short-pitch” fixed wavelength mechanism is still unclear despite Ken’s 40 years of efforts (!), and some are certainly fashionable today (like adhesion and friction at atomic scale). In starting this forum, why not start from here? Should we prepare a 1 page summary on each of these topics? Since I start this, I will do the effort on corrugation I promise in the next week or so!
Regards, Mike
Welcome to a new forum on iMechanica which is specifically designed as a "Contact Mechanics Forum". You do not need to register to view the postings on this forum, but you must register (it's free) in order to post something. The posting can be an idea, an announcement of an upcoming conference, an announcement of a journal article (see node/265), the pdf of the manuscript form of the paper can be posted in many cases (see http://romeo.eprints.org/ for a list of journals which permit it), or almost anything related to contact mechanics.
