力学系与湍流国家重点实验室学术报告8.13(报告人：Jianmin Qu）
发布时间: 2010-08-05 04:55:00
SEMINAR SERIES
北京大学工学院 ![]()
力学与空天技术系
力学与空天技术系 湍流与复杂系统国家重点实验室
题目：Stress-Dependent Chemical Potentials and
Their Applications to Crystalline Solids
Jianmin Qu
Department of Civil and Environmental Engineering,
Department of Mechanical Engineering, Northwestern University
Evanston, Illinois, USA
Abstract: Crystalline solids (e.g., metals and ceramics) used in modern applications (electronics, MEMS, fuel cells, nuclear rectors, etc.) are often subjected to multi-physics driving forces (electrical, chemical, radiological, thermal, mechanical, etc.). The interactions of these different fields often determine the reliability and durability of the crystalline solids. To fully understand how the different driving forces interact requires theories and models that are capable of accounting the coupling of multi-physics processes.
In this talk, a framework will be presented that couples the mechanical and chemical (or electrochemical) fields in crystalline solids via the use of stress-dependent chemical potentials. Two examples of practical interest will be used to illustrate the derivations and applications of the coupled theory. The first example is concerned with the interactions between mechanical stresses and ionic transport in the electrolyte of a solid oxide fuel cell. It is found that the non-uniform oxygen vacancy concentration in the electrolyte can generate significant stresses whose amplitude is comparable to the thermal mismatch induced stress in the cell stack. More importantly, significant stress concentration near processing defects (voids and microcracks) occurs due to the presence of ionic fluxes. The second example is on the stress-oxidation interaction in selective oxidation of binary alloys. Again, it is found that internal oxidation induces significant compressive stress which is responsible for the buckling driven fracture failure of the scale layer. Furthermore, the stress in the scale layer also tends to slow down the rate of oxidation.
Brief CV: Jianmin Qu, Walter P. Murphy Professor in the McCormick School of Engineering and Applied Science at Northwestern University, received his Ph.D. in Theoretical and Applied Mechanics from Northwestern University. Before joining the faculty at his alma mater in 2009, Professor Qu was on the faculty of the School of Mechanical Engineering at the Georgia Institute of Technology from 1989 to 2009. Professor Qu’s research focuses on several areas of theoretical and applied mechanics including micromechanics of composites, interfacial fracture and adhesion, fatigue and creep damage in solder alloys, thermomechanical reliability of microelectronic packaging, defects and transport in ionic solids with applications to solid oxide fuel cells, and ultrasonic nondestructive evaluation of advanced engineering materials. He has authored/co-authored one book, 10 book chapters and over 120 referred journal papers in these areas.
主持人：苏先樾教授
时 间：8月13日（周五）上午10:00~11:30
地 点：力学楼434会议室
欢迎广大师生光临！