英国卡迪夫大学教授Feodor M. Borodich学术讲座
时间 : 2019年11月04日 10时00分
地点 : 重庆大学A区理科楼205
主办单位 : 工程学部
协办单位 : 航空航天学院
Some Adhesive Contact Problems of Nanomechanics and Nanotribology
主讲人 : Feodor M. Borodich
Employing analytical modeling and computer simulations, we study various problems of modern nanomechanics and nanotribology.
Nano-world is the ‘Sticky Universe’, and adhesion caused by van der Waals forces is a universal molecular phenomenon, hence problems of nanomechanics should normally take into account adhesive interactions. It is shown that the classic Hertz, Galin and JKR (Johnson-Kendall-Roberts) theories can be extended to arbitrary convex blunt axisymmetric solids and to materials having rotational symmetry like transversely isotropic or homogeneously prestressed materials. It is shown that the relations between the load, the contact radius and the displacements in adhesive contact for power-law shaped probes reduced to remarkable simple universal dimensionless equations. To apply mechanics of adhesive contact to practical problems, one needs to know the work of adhesion between interacting surfaces. However, this value is not a well-known quantity for many modern materials and existing direct methods for its determination are not stable and reliable. A relatively new BG method allows the researchers to determine adhesive and elastic properties of contacting materials by numerical approach to experimental force-displacement unloading curves for spherical indenters. It is proposed to apply the results obtained and the BG method to prestressed membranes of biological cells.
It is shown that various physical and tribochemical processes that occur at micro and nano-scales during rubbing, have to be taken into account for proper numerical simulations of dry friction phenomenon. Structural multi-level and multiscale models of surface roughness are presented. The models reflect the dual nature of friction: mechanical and adhesive interactions between counterparts. Numerical simulations show that the force of friction is not constant; it dependents on the local features of the roughness profile of the substrate. However, in general, the Amontons law is confirmed. Our simulations help to understand the governing processes and factors of the dry friction phenomenon and the influence of the environmental conditions on the performance of the modern super-low friction coatings.
The talk is oriented to a very wide auditory. No previous knowledge in the subject is assumed.
Professor F.M. Borodich holds several degrees in Mechanics and Applied Mathematics (MSc 1979, PhD 1984, DSc 1990) awarded by the Department of Mechanics and Mathematics at Moscow State University (Russia), and MSc degree with distinction in Civil Engineering (Moscow, Russia 1985). He is Elected Member of Academy of Nonlinear Sciences and Foreign Member of Russian Academy of Natural Sciences. In 2016 he was awarded by Honorary Doctor of Science degree of V.A. Belyi l-Polymer Research Institute (Nat. Ac. Sci. Belarus). In 1979-1994 he worked in Moscow where he got a Teachin Certificate as a Professor of Applied Mathematics. In 1995-2001 he held various research and teaching positions at several universities including Cambridge (UK), Hannover (Germany), Glasgow (UK), and Barcelona (Spain). In 2001-2003 he was a full-time visiting professor at Professor Leon Keer group of Northwestern University (USA). Since 2004, he is a Professor and the Head of Cardiff Nano-Science and Nano-Engineering Cross-Disciplinary Group (NANOSNEG) at Cardiff University. His research interests are in a number of areas of Engineering, Mechanics and Applied Mathematics related to modelling real-world processes especially problems of Nanomechanics and Nanotribology. In particular, he obtained new results in static and dynamic contact problems, self-similar models and scaling in solid mechanics, nanoindentation, nanomanufacturing, nanotribology, mechanics of adhesive contact, de ions of rough surfaces, modelling of dry friction and friction-induced oscillations, and other related topics.