SUBJECT: Ph.D. Dissertation Defense
BY: Amirreza Keyhani
TIME: Thursday, July 9, 2020, 3:00 p.m.
PLACE:, Online
TITLE: Mesoscale Thermo-mechanical Response of Traditionally and Additively Manufactured Energetic Materials to Dynamic Loading
COMMITTEE: Dr. Min Zhou, Chair (ME)
Dr. Richard Neu (ME)
Dr. Antonia Antoniou (ME)
Dr. Shuman Xia (ME)
Dr. Julian Rimoli (AE)


The thermo-mechanical responses of traditionally manufactured polymer-bonded explosives (PBXs) and an additively manufactured energetic material (AMEM) simulant under dynamic loading are studied. The AMEM simulant is unidirectionally printed using direct ink writing (DIW) of a high solid-loaded photopolymer and cured under UV-light exposure. To analyze the thermo-mechanical response and ignition behavior of PBXs, a cohesive finite element framework is used. The analyses focus on material behavior at various levels of constituent friction and plasticity, and load intensity. The time to ignition is analyzed and quantified, providing explicit expressions for the ignition probability as a function of load intensity, load duration, and constituent properties. AMEMs have a wide range of structural characteristics and process-inherent heterogeneities which are hitherto difficult to precisely control. Therefore, it is essential to understand how these features affect AMEMs' response under dynamic/shock to tailor these materials for applications. To study the thermo-mechanical response of the AMEM simulant, quasi-static mechanical tests, intermediate strain rate Split-Hopkinson pressure bar (SHPB) experiments integrated with simultaneous high-speed visible and thermal imaging, and high strain rate x-ray phase-contrast imaging (PCI) experiments are performed. The experiments capture deformation modes and corresponding temperature signatures in the AMEM simulant. However, the effects of microstructural attributes and frictional and inelastic dissipation cannot be quantified experimentally due to limitations of available diagnostics. Therefore, experimentally-informed finite element simulations are also performed to gain the quantification. The microstructural attributes are found to significantly affect the development of hotspots. This dissertation establishes trends in and quantification of the relations between structure and response of a class of AMEM simulants.