(LNM-10月13日11:00)Meso-Scale Diagnostics for Fields of Temperature,Deformation,and Stress in Heterogeneous Materials
Meso-Scale Diagnostics for Fields of Temperature,Deformation,
and Stress in Heterogeneous Materials
报告人: Prof. Min Zhou
The George W. Woodruff School of Mechanical Engineering,
The School of Materials Science and Engineering, Georgia Institute of Technology, USA
The deformation of materials is an intrinsically combined mechanical and thermal process at the microstructural level. The deformation, temperature and stress fields in materials reflect the fundamental mechanisms governing the process. Although fields of deformation are readily measured, especially at larger size scales and slower time rates, temperature fields at small scales and dynamic rates have hitherto been beyond available experimental capabilities. The lack of such measurements represents a significant impediment to the development of new materials for specific applications. Here, I will describe an effort at developing a novel experimental capability for simultaneous measurements of meso-scale temperature and deformation fields at dynamic strain rates. The thermal measurement is a novel first-time ever experimental capability for recording the spatial distribution and temporal evolution of microstructure-level temperature fields. This ground-breaking technique uses a custom-made high-speed infrared (IR) camera with the latest available technology and has spatial resolutions up to 12 microns and time resolutions as fast as 55 microseconds per frame. The visible light (VL) imaging part uses a high-speed digital camera and digital image correlation. The combined IR and VL diagnostics lend itself to analysis of heterogeneous materials. I will also describe a novel technique for measuring stress at the micron level using multilayer optical microcavity structures (OMC). Another complementary technique being pursued is a reflectance-change-based active lighting technique for recording of temperature fields.
Min Zhou is George W. Woodruff Professor of Mechanical Engineering and Materials Science and Engineering at Georgia Tech. He received his Ph.D. from Brown University in 1993 and was a postdoctoral fellow at Caltech between 1993 and 1995. He joined the faculty at Georgia Tech in 1995. His research focuses on material behavior at several length scales, emphasizing molecular dynamics simulations, multiscale continuum modeling, and experiments with laser interferometry and digital diagnostics. Dr. Zhou is a recipient of the US National Science Foundation (NSF) CAREER award and Sigma Xi Society Georgia Chapter Best Paper Award. He is also a Fellow of the American Society for Mechanical Engineers (ASME).