報告題目：

　　1. World of Materials Research in MSE @ Georgia Tech

　　2. Multilayer Optical Structures for Time-Resolved Meso-Scale Sensing of Shock Compression Effects in Heterogeneous Materials

　　報告人：NareshThadhani

　　報告時間：2016年9月29日上午10:00

　　報告地點：研究生樓101報告廳

　　報告人簡介：

　　Professor NareshThadhani is Chair of the School of Materials Science and Engineering at the Georgia Institute of Technology, where he has been on the faculty since 1992. His current research focuses on probing the mechanisms of shock-induced physical and chemical changes and the deformation and fracture response of various materials under shock compression and high-rate impact loading conditions. He has graduated 21 Ph.D. and 18 M.S. degree students. He is Fellow of the American Physical Society and of ASM International. He has authored of more than 300 publications in journals and conference proceedings, and is Editor of Springer Book Series on Shock Compression, Associate Editor of Journal of Dynamic Deformation of Materials and Shock Waves: An International Journal, Key Reader for Metallurgical and Materials Transactions, and Past President of Alpha Sigma Mu.

　　報告簡介:

　　The School of Materials Science and Engineering (MSE) at Georgia Tech (GT) is one of the largest and most diverse materials programs. Our research portfolio spans all classes and forms of materials addressing a multitude of functionalities from structural load-bearing to energy storage and harvesting; and electronic, photonic, and opto-electronic devices to drug delivery and implants. As a world leader in educating the next generation of scientists and engineers, our vision is to define the future of MSE through academic excellence and research innovations focused on envisioning, predicting, designing, and developing materials for tomorrow’s challenges in energy, environment, health and human welfare, infrastructure, security, and transportation.

　　The speech will demonstrate research on the design and testing of novel 1-D photonic crystal sensors based on Distributed Bragg Reflectors (DBRs) which are dielectric stacks composed of alternating layers of high and low refractive index materials, and Optical Micro Cavity (OMC) structures composed of dielectric cavity layer placed between two metal mirror layers. Both structures generate size tunable characteristic spectral properties either through reflectance peak (for DBRs) or reflectance minima (for OMC). The spectral responses of DBR and OMC structure are being investigated under homogeneous and heterogeneous loads, using laser-driven shocks and time-resolved spectroscopy enabled by a spectrograph-coupled streak camera. Optomechanical simulations utilizing a custom multi-physics framework is performed, to correlate predictions to experimental observations. Initial experimental results indicate that the multilayers exhibit a highly time-resolved spectral response to shock compression. Additionally, the multilayers exhibit a spatially-resolved spectral response under heterogeneous shock load. The understanding generated from such spatially and temporally-resolved diagnostics, combined with meso-scale simulations, can help determine the effects of heterogeneities on shock compression of heterogeneous materials.