Engineering Physics Colloquium
Thursday, January 16
106 Engineering Research Building
Speaker: Dr. Yuhang Hu, Harvard University
"Poroelastic Materials: From Fundamental Mechanics to Novel Applications"
Abstract: Poroelastic material is a two-phase system consisting of a porous solid skeleton filled with liquid. The poroelasticity was originally developed for studying the consolidation of soils. In this study, I explore its applicability on polymeric gels, which are composed of cross-linked polymer networks swollen in an aqueous solution. Gels have broad applications in many engineering fields, but are difficult to characterize through mechanical tests because of their soft and brittle characters. Among various testing methods, indentation is recognized as the most practical technique. However, interpreting data from indentation measurement is not trivial. In this talk, I will show that within the theory of poroelasticity, the force relaxation curves from indentation can be obtained in remarkably simple forms, enabling indentation to be used with ease as a method for determining the elastic constants and diffusivity of gels. Besides material characterization, I also explore the novel applications of poroelastic materials. In one example, I will show that the surface topography of a poroelastic material can be continuously tuned from a perfectly smooth one to a rough one due to the liquid's ability to flow and configure in response to the matrix deformation. In particular, I will demonstrate simultaneous control of the material's transparency and its ability to continuously manipulate various low-surface-tension droplets from free-sliding to pinned. In another example, I will show that the liquid's ability to flow and reconfigure also provides a unique gating mechanism. The micro pores of a poroelastic membrane can be se lectively opened and closed for gas and liquid transport while the liquid layer coating around the pores almost completely prevents fouling inside the pores. These novel properties of poroelastic membranes can benefit many industrial and biomedical applications.
Biography: Dr. Yuhang Hu is currently a postdoctoral fellow In Wyss Institute of Bioinspired Engineering and School of Engineering and Applied Sciences at Harvard working with Professor Joanna Aizenberg. She received her bachelor's degree from the Department of Engineering Mechanics at Shanghai Jiao Tong University, China in 2005, and master's degree in Mechanics and Structures from the Department of Civil and Environmental Engineering at Nanyang Technological University, Singapore In 2007. She obtained her Ph.D. in Solid Mechanics from Harvard University working with Professor Zhigang Suo and Professor Joost Vlassak In 2011. Dr. Hu's research focuses on the mechanics of soft materials and bioinspired materials. Her study involves analytical and numerical modeling, mechanical tests, materials design, and fabrication.