报告人：密西西比州立大学 刘宇澄 教授
时 间：2019年6月5日上午 9:00-10:30
题 目：Experimental Analysis and Computational Modeling of Electroplasticity of Nonferromagnetic Ductile Metals
A multi-physics Internal State Variable (ISV) theory that couples the thermo-elasto-visco-plastic-damage model of Bammann with electricity-related electromagnetic phenomena was formulated with internally consistent kinematics, thermodynamics, and kinetics. An innovative methodology to experimentally distinguish the ElectroPlastic (EP) effect from the thermal expansion was developed and applied to experimentally validate the proposed theoretical electro-mechanical model. Three series of quasi-static uniaxial tension experiments with titanium, copper, and zinc were conducted and a quadratic dependence of the EP stress drop on the electric current density was observed. This study experimentally confirmed the existence of EP as an electron-dislocation interaction phenomenon. The significance of the non-EP effects in the electro-mechanical coupling problems was estimated. The experimental procedure limitations were thoroughly discussed as well as the sensitivity and uncertainty, associated with each of the model parameters. Conclusions and suggestions for future work supplement the study. This piloting work on electro-mechanical coupling opened new horizons for modeling and experimental observation of the electroplastic effect.
Dr. Yucheng Liu is the Jack Hatcher Chair Professor in the Department of Mechanical Engineering (ME) at Mississippi State University (MSU) and he currently serves as Graduate Coordinator in that department. Prior to joining MSU in 2014, Dr. Liu was the Assistant Professor of the ME Department at the University of Louisiana at Lafayette (UL Lafayette). Dr. Liu received his PhD degree from the University of Louisville in 2005 and Bachelor’s Degree from the Hefei University of Technology in 1997, both in Mechanical Engineering. Dr. Liu’s research has historically focused on the areas of multiscale material modeling and simulation, high strain rate performance of materials, vehicle systems design and analysis, and hydropower and wave energy technology. His current research interests and activities center on gaining a better understanding of the process-structure-property-performance relations of structural materials through advanced multiscale theoretical framework and integrated computational and experimental methods. To date, Dr. Liu has published about 200 peer reviewed publications, including more than 100 peer reviewed journal articles. He has been the PI and co-PI for over 40 research projects funded by NSF, DOD, DOE, NASA, FAA, Louisiana Board of Regents, and industry with the total amount of $8.2M. Dr. Liu has served as a panelist or a reviewer for several NSF, DOD, NASA, and DOE programs. Dr. Liu is a Professional Engineer registered in Ohio State and holds active membership in ASME, SAE, AAAS, and ASEE. Dr. Liu received the Junior Faculty Researcher of the Year of the College of Engineering at UL Lafayette in 2013, the Outstanding Senior Faculty Research Award from the ME Department in 2016, and MSU Faculty Research Award in 2018. He was elected ASME Fellow in 2017, named to the Jack Hatcher Chair in Engineering Entrepreneurship in 2018, and promoted to Full Professor in 2019.