报告题目：

Multilayer Optical Structures for Time-resolved Meso-scale Sensing of Shock Compression Effects in Heterogeneous Materials

报告人:  Naresh N. Thadhani，Professor and Chair

School of Materials Science & Engineering, Georgia Institute of Technology, USA

时间：2016年9月27日(周二)  10: 00-11: 30        

地点：中科院力学所1号楼344会议室

报告摘要：

Heterogeneous materials including geological materials such as soils and rock, to composites such as laminates or energetic particulate compacts, have complex shock compression behaviors due to the interactions of shock waves with the heterogeneities. Many descriptive and predictive models fail to capture the meso-scale mechanisms that drive macroscopic responses to dynamic mechanical loads, due to lack of experimental validation of processes occurring at such length scales. This is particularly challenging for shock compression, where key mesoscale interactions operate on timescales of nanoseconds to microseconds. To address this critical gap, we are investigating 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 that can be clearly observed in reflection either through reflectance peak (for DBRs) or reflectance minima (for OMC). In this presentation, the use of meso-scale in-situ diagnostics employing one-dimensional photonic crystals based on multilayer DBR and OMC structures, for time-resolved meso-scale sensing of shock compression in heterogeneous materials will be discussed. 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.

报告人简介：

Thadhani教授，佐治亚理工学院材料科学与工程学系(MSE)主任，1984年获新墨西哥矿业与技术学院博士学位，1992年加入佐治亚理工学院材料科学与工程系。研究方向主要包括利用冲击改变新材料的物理、化学和力学性能；高速冲击载荷条件下金属、陶瓷、聚合物和复合材料的变形和破坏响应。Thadhani教授因在材料冲击物理研究方面的贡献，当选为Fellow of ASM International and American Physical Society。