Seminar Schedule – Spring 2022
Thursday, April 21, 2022
Time: 3:30pm – 4:30pm
This seminar will be held in-person in ASE 1.126.
Mechanics of Interfaces with Tunable Adhesion
Kevin T. Turner
Department of Mechanical Engineering and Applied Mechanics
University of Pennsylvania
Abstract
While adhesive interfaces have traditionally been engineered to provide strong and permanent bonding, interfaces with tunable or switchable adhesion have gained significant interest in recent years. Efforts to develop interfaces with tunable adhesion have been driven by applications such as robotic grasping and locomotion, clutches to realize variable stiffness in robotics and prosthetics, small-scale pick-and-place manufacturing processes, and microtransfer printing. The effective adhesion strength of an interface can be modulated through control of the surface interactions as well as the local stress-state at the interface. In all cases, the mechanics of the interface must be carefully engineered to realize high adhesion strength in one state and low adhesion in the other state. In this talk, a general mechanics-based framework for designing interfaces with tunable adhesion will be presented and multiple systems with tunable adhesion will be discussed. In one class of systems, structured elastic heterogeneity is used to tailor the stress distribution at the interface and hence the effective adhesion strength. Fracture-mechanics based models, analytical and computational, are used to design systems that can be tuned passively via loading direction or actively via stiffness modulation of one component. The performance of these systems has been experimentally validated and applied in pick-and-place and microtransfer printing processes. In a second class of systems, electrostatic adhesion is used modulate interface behavior. Modeling and experiments show that realizing adhesion capacity and the switching ratio require careful control of both the overall contact geometry as well as the fine scale roughness of the surfaces for electroadhesion to be exploited effectively.
Bio: Kevin T. Turner is a Professor and the Chair of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. Professor Turner holds a secondary appointment in Materials Science and Engineering and is also the Penn site director of the NSF-funded Engineering Research Center for Internet of Things for Precision Agriculture (IoT4Ag). He received his BS from the Johns Hopkins University and SM and PhD from the Massachusetts Institute of Technology. He has received numerous awards, including the Lindback Award for Distinguished Teaching, ASME Sia Nemat-Nasser Early Career Award, Adhesion Society – Young Adhesion Scientist Award, and NSF Career Award. Turner’s research is at the nexus of mechanics, manufacturing, and materials. Ongoing research efforts in Turner’s group include structured materials with tunable adhesion and fracture properties, soft robotic grasping, design of heterogeneous and additively manufactured materials, and manufacturing of flexible hybrid electronics and sensors.
For further information, please contact Dr. Kenneth Liechti at kml@mail.utexas.edu or (512) 471-4164.
