讲座题目：New Tunable Reusable Energy Damping System

报告人：Prof. Guoxin Cao

时 间：9月24日（周五）下午3:30
地 点：力学楼434会议室

报告内容摘要：
      Energy damping system (EDS) is required to absorb/damp mechanical energy when they are under the external mechanical load, which are widely used for protecting against the damage caused by impact or blast load, e.g. protection layer of electronics, car bumper and helmet. Due to a long response time, a localized deformation under high loading rate and unable to reuse, the conventional EDS is not effective to resist the high-speed loads (e.g. blast or high-speed impact), and, thus, developing a new EDS is very necessary.
      A new tunable reusable energy damping system was developed, which is based on the nanoporous particles with nonwetting liquid sealed inside a container. The working mechanism of the new EDS is as follows: Under the normal condition, the nonwetting liquid is outside of the nanopores; and when the system is under the external load, the nonwetting liquid will be pressed into the nanopores. The work done by the external load can be converted into the solid-liquid interfacial energy and internal friction energy (dissipated as heat), and, thus, the mechanical energy is damped. Due to the high specific surface area/mass ratio, this system has the potential of becoming ultrahigh performance EDS.
       Both the numerical and experimental studies are employed to understand the mechanism of energy damping and the effects of the system parameters on the energy damping performance, e.g. the nanopore size, liquid flow rate inside nanopore, liquid viscosity and solid-liquid surface interaction energy. The results show that the new EDS can be a potential candidate to effectively damp the mechanical energy for both static and dynamic loads. In addition, by adjusting the system parameters, the system can be not only tunable to resist the different pressure levels to make it more effective for all purpose protections but can also be reused to protect against the repeatable loads.

报告人简介：
      Dr. Guoxin Cao is currently working as an associate professor (PH.D advisor) in the Department of Mechanics and Aerospace Engineering at College of Engineering of Peking University. He got his PH.D. in the Department of Material Science and Engineering at Clemson University in 2004, and then, he worked as a Postdoctoral Research Scientist in the Department of Civil Engineering and Engineering Mechanics at Columbia University. Before joining Peking University, he worked as a research assistant professor in the Department of Engineering Mechanics at the University of Nebraska-Lincoln. His research areas are mainly about multiscale simulations of the advanced materials and systems, nanomechanics and biomechanics. He has authored and co-authored over 50 journal papers, and some of them are published in the high profile journals, such as PRL, JACS, Nanoletter and JMPS.