Jackson Smith

Advisor: Dr. Naresh Thadhani, School of Materials Science and Engineering, Georgia Tech

will propose a doctoral thesis entitled,

Effects of Shock-Induced Phase Transitions on Spall Failure in Fe-Mn Alloys

On

April 10th 11am-12pm

in

MRDC Conference Room 4404

or

Virtually via MS Teams:

https://teams.microsoft.com/meet/24580206923253?p=4eahVoyrXlghBinrjR

Committee:

Dr. Naresh Thadhani, School of Materials Science and Engineering, Georgia Tech (Advisor)

Dr. Josh Kacher, School of Materials Science and Engineering Georgia Tech

Dr. Levent Degertekin, School of Mechanical Engineering, Georgia Tech

Dr. Nathanial Helminiak, School of Civil and Mechanical Engineering, United States Military Academy

Dr. Jeffrey Lloyd, Branch Chief, Armor Mechanisms Branch DEVCOM Army Research Laboratory

Abstract:

This work will establish the understanding of how shock-induced α (bcc) → ε (hcp) phase transformations modify both shock-wave evolution and subsequent dynamic tensile failure in Fe–Mn alloys. Plate-impact experiments coupled with time-resolved interferometry will be used to systematically examine how increasing Mn content lowers the transformation threshold and alters wave structure, including rise-time broadening and modified release behavior. These transformation-driven changes are expected to correlate with measurable increases in inferred spall strength and discontinuities in post-spall ringing behavior, indicating that phase transformations dissipate shock energy and fundamentally alter the tensile loading path responsible for spall failure. Building on the observation of signatures of these effects in time resolved interferometry profiles, the proposed work will combine volumetric damage evaluation and targeted post-mortem microstructural characterization (SEM/EDS and EBSD) to evaluate how transformation-induced shock dissipation modifies void nucleation, growth kinetics, damage localization, and spall-plane morphology. The proposed approach will isolate the roles of wave-history modification, interface-driven wave interactions, and transformation-induced microstructural evolution in governing spall failure. The expected outcome is a mechanistic understanding of transformation-assisted shock dissipation and interface-mediated wave disruption, enabling predictive design guidance for next-generation Fe-based materials and architected systems that mitigate impact damage without catastrophic failure.