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SUMMARY:Strength of Adhesive Contacts: Experiment and numerical simulation
DTSTART:20171208T121500
DTEND:20171208T131500
DTSTAMP:20260404T133122Z
UID:77fa550acb378363bb0e2d14df5019de74f6e4709366afd8abec0edb
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dr Valentin L. Popov\, Technische Universität Berlin\, 
 Germany\nValentin L. Popov\, Roman Pohrt\, Qiang Li\, Technische Universit
 ät Berlin\, Germany\n\nAbstract : The strength of an adhesive contact bet
 ween two bodies can strongly depend on the macroscopic and microscopic sha
 pe of the surfaces. In the past\, the influence of roughness has been inve
 stigated thoroughly. However\, even in the presence of perfectly smooth su
 rfaces\, geometry can come into play in form of the macroscopic shape of t
 he contacting region. Here we present numerical and experimental results f
 or contacts of rigid punches with flat but oddly shaped face contacting a 
 soft\, adhesive counterpart. When it is carefully pulled off\, we find tha
 t in contrast to circular shapes\, detachment occurs not instantaneously b
 ut detachment fronts start at pointed corners and travel inwards\, until t
 he final configuration is reached which for macroscopically isotropic shap
 es is almost circular. For elongated indenters\, the final shape resembles
  the original one with rounded corners. We describe the influence of the s
 hape of the stamp both experimentally and numerically.\nNumerical simulati
 ons are performed using a new formulation of the Boundary Element Method f
 or simulation of adhesive contacts suggested by Pohrt and Popov. It is bas
 ed on a local\, mesh dependent detachment criterion which is derived from 
 the Griffith principle of balance of released elastic energy and the work 
 of adhesion. The validation of the suggested method is made both by compar
 ison with known analytical solutions and with experiments. The method is a
 pplied for simulating the detachment of flat-ended indenters with square\,
  triangle or rectangular shape of cross-section as well as shapes with var
 ious kinds of faults and to “brushes”. The method is extended for desc
 ribing power-law gradient media.\nAdditionally\, we discuss some implicati
 ons of this work for simulations of material behavior\, in particular adhe
 sive wear.\n\nBio : Valentin L. Popov is full professor at the Berlin Univ
 ersity of Technology\, studied physics (1976-1982) and obtained his doctor
 ate in 1985 from the Moscow State Lomonosov University. He worked at the I
 nstitute of Strength Physics of the Russian Academy of Sciences. After a g
 uest professorship in the field of theoretical physics at the University o
 f Paderborn (Germany) from 1999 to 2002\, he has headed the department of 
 System Dynamics and the Physics of Friction of the Institute of Mechanics 
 at the Berlin University of Technology. His areas of interest include trib
 ology\, nanotribology\, tribology at low temperatures\, biotribology\, the
  influence of friction through ultrasound\, numerical simulation of fricti
 onal processes\, research regarding earthquakes\, as well as topics relate
 d to materials science such as the mechanics of elastoplastic media with m
 icrostructures\, strength of metals and alloys\, and shape memory alloys. 
 He has published over 100 papers in leading international journals during 
 the past 5 years. He is the author of the book "Contact Mechanics and Fric
 tion: Physical principles and applications" which appeared in three German
 \, two English\, Chinese\, and Russian editions and co-author of the book 
 on “Method of dimensionality Reduction in Contact Mechanics and Friction
 ” which appeared in German\, English and Chinese editions. He is the joi
 nt editor of international journals and regularly organizes international 
 conferences and workshops over diverse tribological themes. He is a member
  of the Scientific Council of the German Tribological Society. He has inte
 nsively collaborated with many industrial corporations and possesses exper
 ience in implementing the results of scientific research in industrial app
 lications.
LOCATION:GC C3 30 https://plan.epfl.ch/?room=GCC330
STATUS:CONFIRMED
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