SUBJECT: Ph.D. Dissertation Defense
BY: Yingdan Wu
TIME: Tuesday, May 19, 2020, 10:00 a.m.
PLACE: Meeting URL:, Online
TITLE: Schallamach Waves and Friction-Induced Self-Oscillations in a Prototypical Belt Drive System
COMMITTEE: Dr. Michael Varenberg, Co-Chair (Mechanical Engineering)
Dr. Michael J. Leamy, Co-Chair (Mechanical Engineering)
Dr. Itzhak Green (Mechanical Engineering)
Dr. Aldo A. Ferri (Mechanical Engineering)
Dr. Matthew Brake (Mechanical Engineering, Rice University)


The high adhesive friction between an elastomer and its counterpart generally impedes sliding in the accepted sense. Instead, displacement is accommodated by Schallamach waves of detachment, which are surface wrinkles that move across the contact zone. However, this has received little research attention in belt drive systems; sliding-based friction models are invariably employed for belt drive mechanics studies. In light of this discrepancy, the rolling contact mechanics in a simple flat belt drive will be explored by considering Schallamach waves of detachment, with particular focus as follows. 1) A thorough understanding of the mechanism of detachment events and friction generated at the belt-pulley interface will be developed. 2) The characteristics of detachment wave-induced oscillations, including the belt and pulley’s oscillations, will be studied, focusing on their dependence on driving speed, loading conditions and the system’s inertia. Also, it is of interest to examine these waves and the global system oscillations in a fully-coupled manner such that 3) downstream effects of detachment events couple to the dynamic response of the belt drive system, and 4) the system’s dynamics couple to the generation of detachment waves. Further, the research intends 5) to propose a rolling friction model for elastomers, capable of computing mechanical energy losses associated with the contact instabilities. 6) A novel surface design will be examined to check the ability to influence, control and tailor the presence of detachment wave-induced oscillations in belt drives. 7) Belts incorporating tensile cords, which are more comparable to belts used in industry, will be examined to find whether detachment waves are universal in belt drive systems. (Meeting URL: