Mechanics of Interfaces with Switchable Adhesion

with Kevin T Turner,
Professor and the Department Chair,
Mechanical Engineering and Applied Mechanics,
University of Pennsylvania

March 28, 2:00 PM
North End Center, Room 2420 

Traditionally, adhesive interfaces are optimized to realize strong and permanent bonds. However, emerging robotics and manufacturing applications require interfaces with tunable and switchable adhesion.  Interfaces with switchable adhesion need to be engineered to realize high adhesion strength in one state and low adhesion in the other. 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. Here, a general mechanics-based framework for designing interfaces with switchable adhesion is presented, and several implementations are investigated and experimentally demonstrated. In one class of systems, structured elastic heterogeneity is used to tailor the stress distribution at the interface and hence the effective adhesion strength. Analytical and computational fracture mechanics-based models are used to design systems that can be tuned passively via loading direction or actively via stiffness modulation. In a second class of systems, electrostatic forces are used to control interface behavior.  Mechanics modeling is critical for the designing of electroadhesive systems, and we show that an understanding of interface mechanics can be exploited to realize higher performance electroadhesive devices.   

Kevin T.  Turner is a Professor and the Department Chair of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. He holds a secondary appointment in Materials Science and Engineering and is 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 materials with tunable adhesion, friction, and stiffness for applications in robotics, the design of damage tolerant heterogeneous and additively manufactured materials and printed and biodegradable sensors for IoT applications.