硕博专题演讲公告

1、碩博專題演講公告題目：Dynamic Growth of Microvoid in Crystalline Materials Study by Dislocation Dynamics and Continuum Mechanics主講人：Dr. T. Calvin Tszeng學歷：Ph.D. University of California, Berkeley, Department of Mechanical Engineering (1987/12)博士論文：Residual Stress Calculations by Finite Element Method in Manufa

2、cturing.指導教授：Shiro KobayashiM.S. National Tsinghua University, Department of Power Mechanical Engineering (1981/6)B. S. National Tsinghua University, Department of Power Mechanical Engineering (1979/6)經歷：Berkeley Materials Research, Piedmont, CA. Founderand President (2004/8 )University of Californi

3、a, Berkeley, Department of Mechanical Engineering, Visiting Professor, (2004/82005/5) Southwest Research Institute (SWRI), San Antonio,（2004）Illinois Institute of Technology, Chicago, Illinois, Department of Mechanical, Materials and Aerospace Engineering, Research Associate Professor, (2004/6 2005/

4、6); Assistant Professor (1998/8 2004/6)University of Nebraska Lincoln. Assistant Professor, Department of Mechanical Engineering (1997/81998/8)Scientific Forming Technologies Corporation, Columbus,Ohio. Principal Research Scientist (1993/3-1997/8)時間：10月12日(五) 下午15:0016:00地點：成功校區測量系經緯廳摘要：Nucleation a

5、nd growth of microvoids are fundamental to the incipient fracture in engineering materials. This study is aiming at capturing the physics and its length-scale dependence of microvoid growth in high strain rate tensile loading. By examining the micromechanics of dislocation along slip planes for both

6、 prismatic loop and shear loop in single crystal, the study quantitatively shows that dislocation emission is the viable mechanism of void growth in high strain rate loading. A dynamic model of void growth is developed by considering conservation of local energies, including plastic dissipation asso

7、ciated with gliding dislocations. The growth rate reaches a steady value that depends primarily on applied stress, mass density and magnitude of lattice friction. Higher dislocation immobility leads to more localized plastic deformation surrounding the void, and a higher growth rate. The same subjec

8、t is also being studied in the framework of continuum mechanics. In the process, a decades old mechanics problem is solved, that is associated with the expansion of a cylindrical void. The present work provides solutions to several outstanding issues common to all the prior publications on this subj

9、ect. The continuum models reconcile with the dislocation dynamics model at loading exceeding a threshold. A new phenomenon of unstable void growth is identified when materials are subjected to repeated, inter-critical loading. The characteristics of void growth are similar to that of fatigue failure

10、, but featuring an instability threshold. The theoretical development is being substantiated by experiments using laser shock peening.歡迎參加!材料科學及工程學系主辦碩博專題演講公告題目：Nanostructured electrode materials for fuel cell applications 主講人：孫嘉良博士學歷：Ph.D.交通大學材料所（2002/10）博士論文：鐵電記憶體場效式電晶體應用之鐵電薄膜材料製程及特性研究指導教授：陳三元博士M.

11、S.交通大學材料系（1999/6）B. S.清華大學材料系（1998/6）經歷：中央研究院原子與分子研究所博士後研究員（2003/1）Visiting Worker, Institute for Chemical Processing and Environmental Technology, National Research Council, Canada (2006, Research Advisor: Dr. Barry MacDougall)時間：10月12日(五) 下午16:0017:00地點：成功校區測量系經緯廳摘要：From former United States Vice

12、President Al Gores “An Inconvenient Truth” to recent booming oil price, looking for clean energy sources becomes a significant, inevitable way to fulfill a growing global populations demand without sacrificing our environment. 1 Particularly for transport, to date fuel cells remain one of the most p

13、otential solutions as clean power sources of electric vehicles. In the beginning of this talk, the operational principles of low temperature fuel cells like direct methanol fuel cells and proton exchange membrane fuel cells will be briefly introduced. 2 The conceptual products and prototypes demonst

14、rated by well-known companies will be shown. As a materials scientist, I will then focus on and discuss the academic studies of nanostructured electrodes consisting of catalysts, carbons and polymers for fuel-cell applications. From calculations, controlled syntheses, characterization to integration

15、, one will be surprised about the multidisciplinary knowledge researchers need and how much we can investigate in this field. Besides selected important works, several papers from close groups will be highlighted. 3-5 Towards the commercialization of fuel cells, there are not only challenges but als

16、o fruitful achievements awaiting us. Reference: Energy 2007. (c) Leeb, S. and Leeb, D. The Oil Factor: Protect Yourself and Profit from the Energy Crisis; Business Plus: 2005. (d) Leeb, S. and Leeb, D. The Coming Economic Collapse: How You Can Thrive When Oil Costs $200 a Barrel; Business Plus: 2007. 2. Handbook of Fuel Cells, Fundamentals, Technology and Applications; Vielstich, W., Lamm, A., Gastei