{"638757":{"#nid":"638757","#data":{"type":"event","title":"PhD Defense by Travis J. Voorhees","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003ETHE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nGEORGIA INSTITUTE OF TECHNOLOGY\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nUnder the provisions of the regulations for the degree\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nDOCTOR OF PHILOSOPHY\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\non Tuesday, September 22, 2020\u003Cbr \/\u003E\r\n12:00 PM\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003Evia \u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E\u003Ca href=\u0022https:\/\/teams.microsoft.com\/l\/meetup-join\/19%3ameeting_MzkwNjcwZjgtOTc4Yi00ZmNkLWFmM2QtNTIwZDA4MTE5OGM0%40thread.v2\/0?context=%7b%22Tid%22%3a%22482198bb-ae7b-4b25-8b7a-6d7f32faa083%22%2c%22Oid%22%3a%2211c4be9e-0787-48f5-8d5e-9cda1b0c7a2b%22%7d\u0022 title=\u0022https:\/\/teams.microsoft.com\/l\/meetup-join\/19%3ameeting_MzkwNjcwZjgtOTc4Yi00ZmNkLWFmM2QtNTIwZDA4MTE5OGM0%40thread.v2\/0?context=%7b%22Tid%22%3a%22482198bb-ae7b-4b25-8b7a-6d7f32faa083%22%2c%22Oid%22%3a%2211c4be9e-0787-48f5-8d5e-9cda1b0c7a2b%22%7d\u0022\u003EMS Teams Video Conferencing\u003C\/a\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E(Click hyperlink to attend)\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nwill be held the\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nDISSERTATION DEFENSE\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nfor\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nTravis J. Voorhees\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u0026quot;High Precision Measurements And Modeling Of How Brittle Granular Materials Behave Under Shock Compression\u0026quot;\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nCommittee Members:\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Naresh Thadhani, Advisor, MSE\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EDr. D. Anthony Fredenburg, Co-advisor, Los Alamos National Laboratory\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Min Zhou, ME\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Kimberly Kurtis, CEE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Preet Singh,\u0026nbsp; MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cbr \/\u003E\r\n\u003Cstrong\u003EAbstract:\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe objective of this research is to develop a model or modeling approach that can accurately predict the dynamic compaction behavior of brittle powders as a function of measureable initial state parameters. To generate the framework for a predictive model, the dynamic compaction behavior of a model brittle powder, CeO\u003Csub\u003E2\u003C\/sub\u003E, is investigated using a combined experimental and computational approach. The Hugoniot states of CeO\u003Csub\u003E2\u003C\/sub\u003E powder at four initial pressed densities are measured via plate impact experiments and used to calibrate continuum compaction models. Empirical fitting parameters for the continuum compaction models are investigated for correlations with the CeO\u003Csub\u003E2\u003C\/sub\u003E powder initial density. The single fitting parameter of the \u003Cem\u003EP\u003C\/em\u003E-\u003Cem\u003E\u0026alpha;\u003C\/em\u003E Menikoff-Kober compaction model,\u003Cem\u003E P\u003Csub\u003EC\u003C\/sub\u003E\u003C\/em\u003E, is shown to exponentially increase with increasing initial density,\u0026nbsp;\u0026rho;\u003Csub\u003E00,\u003C\/sub\u003E\u0026nbsp;and is replaced in the model with a functional form, \u003Cem\u003EP\u003Csub\u003EC\u003C\/sub\u003E\u003C\/em\u003E(\u0026rho;\u003Csub\u003E00\u003C\/sub\u003E), producing a semi-empirical predictive compaction model.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ETo investigate the applicability of compaction models to nonplanar compression scenarios, three commonly used continuum compaction models are calibrated to the experimentally measured planar impact Hugoniot data and used to computationally design validation experiments. Two validation experiments are executed on 3.95 and 4.03 g\/cm\u003Csup\u003E3\u003C\/sup\u003E CeO\u003Csub\u003E2\u003C\/sub\u003E powder targets using the pulsed power driver PHELIX. In situ measurements of the CeO\u003Csub\u003E2\u003C\/sub\u003E densification response are performed with proton radiography and analyzed against the model predictions. Compaction behavior is found to be best captured with a \u003Cem\u003EP\u003C\/em\u003E-\u003Cem\u003E\u0026alpha;\u003C\/em\u003E model, which calculates CeO\u003Csub\u003E2\u003C\/sub\u003E powder bulk densities within 80-99% of experimental values but overpredicts densification at the cylindrical target\u0026rsquo;s outer radius and center by up to 20%.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe contribution of CeO\u003Csub\u003E2\u003C\/sub\u003E powder strength to its nonplanar compaction response is investigated using an elementary porous strength model. This porous strength model is employed by calibrating a strength model for solid CeO\u003Csub\u003E2 \u003C\/sub\u003Ethen applying a linear transformation with respect to porosity to define porous CeO\u003Csub\u003E2\u003C\/sub\u003E strength.\u0026nbsp; Preliminary simulations of the PHELIX experiment using decoupled compaction and strength models show improved accuracy in late-time density calculations. Additional research into which strength models and solid-to-porous transformation methods produce the most accurate results are necessary to further improve this modeling approach.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe overall outcomes of the work described in this dissertation include (1) an experimental and computational approach that can be used to generate semi-empirical predictive compaction models for brittle and granular materials, (2) a greater understanding of how brittle granular materials compact and deform under both planar and nonplanar shock compression, and (3) discernment between compaction modeling approach accuracies in extrapolated regions of phase space. Extensions of this research may allow the development of a physics-based predictive model for the dynamic compaction of brittle powders.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"High Precision Measurements And Modeling Of How Brittle Granular Materials Behave Under Shock Compression"}],"uid":"27707","created_gmt":"2020-09-03 18:12:07","changed_gmt":"2020-09-03 18:12:07","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2020-09-22T13:00:00-04:00","event_time_end":"2020-09-22T15:00:00-04:00","event_time_end_last":"2020-09-22T15:00:00-04:00","gmt_time_start":"2020-09-22 17:00:00","gmt_time_end":"2020-09-22 19:00:00","gmt_time_end_last":"2020-09-22 19:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}