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Information × Registration Number 0219U001217, 0116U008690 , R & D reports Title Interconnection of dimensional scales in interface of friction: start sliding. popup.stage_title Head Braun Oleg, Registration Date 18-01-2019 Organization Institute of physics NASU popup.description2 The goal of this project was to achieve predicted understanding of friction processes. The project was based on long-term collaboration of O.M. Braun with M. Peyrard (Laboratoire de Physique, Ecole Normale Superieure de Lyon, 46th Alle d'Italie, 69364 Lyon Cedex 07, France) in frame of the theoretical approach to multicontact friction problem. It was shown that at the most fundamental level, multicontact friction can be described as a consequence of sequential breaking and the formation of local contacts, which have some unbroken distribution of the thresholds of destruction. It requires an experimental verification of the theory. That is why we have established contact with the experimental group of Alain Le Bot and Julien Scheibert, UMR5513 - Laboratoire de Tribologie et Dynamique des Systemses, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 ECULLY CEDEX, France). The present project is the continuation of our collaboration on the multicontact friction problem. Despite the fact that the initial question was the study of microscopic friction mechanisms, it turned out that our methods can be used for systems of another extreme scale - in the problem of earthquakes. In fact, the theory of earthquakes significantly affected the friction problem through, for example, the famous model of the Bering-Knopov (BC). But now the exchange of ideas is reversed. Our approach is based on the kinetic equation, and can be used to overview the basic ideas of the earthquake model. The success of this three-year project follows from the list of publications.The main results of our work are the following: We proposed the new approach for measuring friction, and developed the magnetic levitation tribometer, which allows us to study friction with a single point-like contact of sub-millimeter size without destruction of the surfaces; Using the scanning tunneling microscopy and magnetic levitation tribometer methods, we investigated the monolayer films of pure tetracosane (С24H50), octatetracontane (С48H98) and their 50:50 binary mixtures deposited on a highly-oriented pyrolitic graphite, and found that the corresponding monolayers reveal substantial lowering of the friction coefficient for the C24+C48 binary mixture in contrast to pure C24 and C48 monolayers; the lowering of friction is due to a higher mobility of n-alkane molecules along the adsorption furrows; We developed the multicontact friction model which describes the sliding of the PDMS sample with rough surface on the flat glass surface in agreement with the experimental results obtained by the experimental team at EC de Lyon; We developed and studied the generalized BK-type model, which incorporates the aging of contacts and the elasticity of the sliding plate, and showed that it can exhibit quiescence as well as enhanced foreshock activity, depending on the value of the rate of aging of contacts; this provides a generic understanding for seismic quiescence. Дослідження в рамках проекту проводились за допомогою Collaboration was organized with the help of permanent e-mail, regular skype conferences and several visits. Product Description popup.authors Браун Олег Михайлович Васько Артем Анатолійович Марченко Олександр Анатолійович popup.nrat_date 2020-04-02 Close