Events Calendar

Astani Department of Civil and Environmental Engineering Seminar

Speaker: Dr. Chung-Yuen (Herbert) Hui, Proessor, Cornell University

Talk Title: The role of surface stress on the mechanical behavior of soft solids

Abstract: Soft solids are ubiquitous: gels, foams, biomaterials, rubbers, and the stuff that makes up our very bodies. They are orders of magnitude more compliant than conventional engineering materials (e.g., stiff materials such as metals and ceramics). For this reason, the mechanical behavior of stiff solids is controlled by the resistance to bulk deformation: elasticity, plasticity, and the like; the mechanical role of the surface is utterly negligible, as noted by Gibbs. However, the surface of common soft solids carries considerable stress, just as liquids have a surface tension. Consequently, for soft solids, the pervasive influence of surface stress has required re-thinking a wide range of mechanical phenomena and properties. In this talk, I will show examples of phenomena where surface stress has radically changed mechanical behaviour. For example, how small particles interact with soft substrates can be governed more by surface stress than by the elasticity of the substrate. Surface stress can modify adhesion on rough surfaces by flattening them. The contact angle in partial wetting is no longer always governed by Young equation -“ it depends on the surface stress of the solid substrate as well as its elasticity.







Biography: Dr. Chung-Yuen(Herbert)Hui is the Joseph-Ford Professor of Mechanical and Aerospace Engineering(MAE)of Cornell University. He has a Bachelor of Science degree from the University of Wisconsin-Madison majoring in Physics and Mathematics. He received his Master degree in Applied Math and Ph.D.degree in Solid Mechanics from Harvard. He joined the Department of Theoretical and Applied Mechanics(TAM)at Cornell University in 1981 and stayed until 2010, when TAM became part of MAE. His primary research interest is Physics and Mechanics of materials. His recent research is primarily focused on adhesion science, fracture mechanics and mechanics of soft matter. He was the Chairman of Gordon Conference on Adhesion in 2010 and received the Adhesion Society Award for Excellence in Adhesion Science in 2011. He enjoys teaching and received several teaching awards including Tau-Beta-Pi Excellence in Teaching Award.

Host: Dr. Qiming Wang

Location: Zoom: https://usc.zoom.us/j/97228056404; Meeting ID: 972 2805 6404: Passcode: 864779

Audiences: Everyone Is Invited

Contact: Evangeline Reyes