Tribology of Materials Across Length Scales
by Ahmet Deniz Usta
(University of Wisconsin-Madison, Department of Mechanical Engineering)
DATE : May 22, 2019 (Wednesday)
TIME : 15:30-16:30
ROOM : VYKM-2
Designing reliable and long-lasting assembled structures with desired vibration and acoustics characteristics requires tractable models of energy dissipation and stiffness of interfaces between components. Establishing the physical-basis of such models is challenging due to various length scales and mechanisms involved in vibration transmission across interfaces. Namely, length scales from microscale roughness to waviness contribute to adhesive and frictional response of a rough interface. Besides, material damping, elastic-plastic deformations, rate-dependent material properties, surface chemistry and associated adhesion constitute the major mechanisms governing the adhesive and frictional response even for atomically smooth interfaces. In the first part of my talk, I will be presenting the results of a study on the influence of length scales and different mechanisms on overall damping and tangential stiffness of nominally flat rough surfaces. This section is intended as a summary of the main content of my PhD thesis and will conclude with a discussion on open challenges for a better understanding of interfacial damping and stiffness. In the following section, I will share my findings related to two side projects that I was involved in:
- improved wear-resistance in laser micropolished Ti6Al4V surfaces
- tribological and mechanical characterization of human skin substitutes and comparison with human skin.
Ahmet Deniz Usta received his BS degree in mechanical engineering from Bogazici University in 2010. After working as a research assistant at the National Nanotechnology Research Center in Ankara and as a vehicle test engineer at AVL in Kocaeli, he started his PhD in the Department of Mechanical Engineering at the University of Wisconsin-Madison in 2013. As a member of Eriten Research Group, a laboratory with research interests in the areas of tribology, contact mechanics and nonlinear dynamics, he participated in several projects on the tribology of metals, polymers, paper products and biological tissues. Currently, he is a PhD candidate in the same department.