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Engineering Physics Colloquium

Tuesday, October 22

4:00 PM to 5:00 PM

106 Engineering Research Building

Speaker: Professor Melih Eriten, University of Wisconsin-Madison
"Nonlinearities in Presliding Friction"
Abstract: Presliding friction is the resistance to tendency to move in stationary contacts, which appears ubiquitously in nature and engineered systems, such as tectonic plate interactions leading to earthquakes; transmission of traction in rolling motion; mechanical joints in assembled structures; fretting wear of human joint implants; friction-based sound generation in spiny lobsters; thin film and coating-substrate interfaces; fiber-matrix interactions in composites; particle interactions in granular materials; and atomic-scale stick-slip oscillations. In all of these examples, presliding friction constitutes the major source of energy losses and nonlinearities. Due to these energy losses and nonlinearities, sophisticated models of assembled structures fail to predict dynamic responses observed in practice. This, in turn, necessitates use of large safety factor, and expensive surface texturing and coating techniques in design and manufacturing. Researchers have been studying presliding friction since the 1940s. However, load-dependent nonlinearities observed in static friction coefficients, compliance and energy dissipation still remain unresolved. When deformation-based forces are prevalent during presliding, static friction coefficients and compliance are decreasing functions of external loading. In contrast, energy dissipation increases with increasing tangential loading. This rather complicated physics can be understood thoroughly only through testing and modeling at high spatial and temporal resolutions, and involving multiple disciplines including chemistry, materials science, tribology, mechanics, dynamics, and structural engineering. In this talk, I present a multiscale approach to the presliding problem and preliminary results explaining the load-dependent nonlinearities. This multiscale framework promises to couple material and surface properties to contact geometries and external loading. Multiscale nature in spatial and temporal domains is first resolved at asperity-scales, and then, scaled up to practical rough surface-scales. This talk will also highlight the broader applicability of the proposed approach in dynamical systems containing a multitude of contact interfaces. In particular, uneven distribution of nonlinear compliance and damping among vibrational modes of assembled structures will be attributed to nonlinearities in interfacial mechanics and presliding friction.
Biography: Professor Melih Eriten received his bachelor’s degree in mechatronics engineering with a minor in mathematics from Sabanci University, Istanbul, in 2005; and his master’s degree in applied mathematics and Ph.D. in mechanical engineering from the University of Illinois at Urbana-Champaign (UIUC) in 2005 and 2011, respectively. He worked as a postdoctoral research associate at UIUC’s Linear and Nonlinear Dynamics and Vibrations Laboratory and served as a visiting lecturer. In July 2012, Dr. Eriten joined the faculty at the University of Wisconsin-Madison as a tenure-track assistant professor in the department of mechanical engineering. His research interests are in contact mechanics and tribology, multiscale testing, characterization and modeling of materials, and nonlinear dynamics of materials and assembled structures. He is the author/co-author of 20 journal articles and 18 articles in conference proceedings, and has delivered a number of technical presentations and invited talks. In 2012, Dr. Eriten received ASME’s Marshall B. Peterson Award for significant contributions in pre-sliding behavior of frictional contacts.