2017-Sustainable Industrial Processing Summit
SIPS 2017 Volume 5. Marquis Intl. Symp. / New and Advanced Materials and Technologies
| Editors: | Kongoli F, Marquis F, Chikhradze N |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2017 |
| Pages: | 590 pages |
| ISBN: | 978-1-987820-69-0 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Meso-Scale Time-resolved Sensing of Shock-Compression Effects in Heterogeneous Materials
Naresh Thadhani1;1GEORGIA INSTITUTE OF TECHNOLOGY, Atlanta, United States;
Type of Paper: Regular
Id Paper: 32
Topic: 43
Abstract:
Probing the effects of shock-compression in heterogeneous materials consisting of powder mixtures or multi-layered structures used as those used as structural energetic systems, requires meso-scale and time-resolved sensing combining experiments and computations. Impact experiments performed using gas gun or laser-accelerated launching of thin foils coupled with high-speed imaging, stress gauges, and/or interferometry techniques can provide information about evidence of chemical changes based on shifts in the equation of state and/or pressure-volume compressibility. However, these continuum-based diagnostics lack spatial resolution necessary to capture the micro- or meso-scale structural evolution of transition states, extent of reaction, localized changes in reactant configuration(s), or transport processes that lead to reaction. Two-dimensional meso-scale numerical simulations employing actual micrographs of starting reactive constituents imported into a multi-material hydrocode, can provide qualitative and semi-quantitative understanding of the highly-heterogeneous nature of shock-wave interactions with reactants which result in forced/turbulent flow, vortex formation, and even micro-scale dispersion and solid-state mixing as possible processes promoting reaction. However, there is no scale-specific validation of these processes. In our present work we are exploring meso-scale time-resolved diagnostics using quantum dots (QDs) and 1-D multi-layered photonic crystal structures (MLPCs), to experimentally measure spectral signatures which can be used as characteristics of localized stress and strain resulting from shock interactions with heterogeneities. Results of experiments performed on CdTe dispersed in polymer and glass matrix reveal distinct changes in emission intensity and blueshift as a function of shock pressures. Similarly, MLPCs based on Optical Microcavity Structures show time-resolved changes in emission wavelength due to shock loading. The understanding generated through such spatially and temporally-resolved in-situ diagnostics, combined with meso-scale simulations, can enable the design of performance-specific structural energetic/reactive materials.