{"620325":{"#nid":"620325","#data":{"type":"event","title":"Phd Defense by Jason Allen","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003ETHE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EGEORGIA INSTITUTE OF TECHNOLOGY\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EUnder the provisions of the regulations for the degree\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003EDOCTOR OF PHILOSOPHY\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003Eon Wednesday, April 24, 2019\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E12:00 PM\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cstrong\u003Ein Love 295\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003Ewill be held the\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EDISSERTATION DEFENSE\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003Efor\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EJason Allen\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E\u0026quot;Towards the Development of Dual Phase Constitutive Relations for Ti-6Al-4V Based on the Mechanical Threshold Stress Model\u0026quot;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee Members:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Hamid Garmestani, Advisor, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Steven Liang, ME\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Naresh Thadhani, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Preet Singh, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. David McDowell, ME\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EAbstract:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EHigh-speed machining of Ti-6Al-4V parts\u0026nbsp;often subjects the workpiece surface to increased\u0026nbsp;temperatures, high strains and strain-rates and can lead to phase transformations, recrystallization, growth and\u0026nbsp;grain size\u0026nbsp;gradients.\u0026nbsp;The description of the mechanical behavior of dynamic processes depends greatly on a constitutive model being able to account accurately for changes in the flow stress with variations in strain-rate and temperature that occur during processing. The Mechanical Threshold Stress (MTS) model\u0026nbsp;is a physical-based internal state variable model that accounts for this behavior remarkably well.\u0026nbsp;While much work has been invested in parameterizing the MTS model for various material systems, relatively little attention has been given to dual or multiphase systems. Additionally, most applications of the MTS model have been used to describe bulk material behavior without regard to the constitutive behavior at the slip system level.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ETo properly model the constitutive behavior, modifications were made to the MTS model to 1)\u0026nbsp;extend applicability to high-strain rate behavior where thermal dislocation activation transitions to dislocation drag mechanisms and 2)\u0026nbsp;more accurately model the initial work-hardening at the onset of plastic deformation.\u0026nbsp;Using these modifications, single-crystal MTS models for the alpha- and beta-phases of the Ti-6Al-4V system were then\u0026nbsp;developed\u0026nbsp;at the slip system level for use within the Viscoplastic Self Consistent (VPSC) crystal plasticity model to describe the stress-strain behavior of polycrystalline dual-phase Ti-6Al-4V undergoing high strain-rate compression over a wide range of temperatures.\u0026nbsp;Simulations using these models\u0026nbsp;were also carried out to describe the surface texture evolution of the\u0026nbsp;Ti-6Al-4V alpha- and beta-phases\u0026nbsp;undergoing high-speed machining processes.\u0026nbsp;\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Towards the Development of Dual Phase Constitutive Relations for Ti-6Al-4V Based on the Mechanical Threshold Stress Model\u0022"}],"uid":"27707","created_gmt":"2019-04-11 16:07:24","changed_gmt":"2019-04-11 16:07:24","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2019-04-24T13:00:00-04:00","event_time_end":"2019-04-24T15:00:00-04:00","event_time_end_last":"2019-04-24T15:00:00-04:00","gmt_time_start":"2019-04-24 17:00:00","gmt_time_end":"2019-04-24 19:00:00","gmt_time_end_last":"2019-04-24 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":""}}}