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Visitor Seminar: “Computer Simulations of Mechanical, Thermal, and Mass Transport Across 6+ Length Scales towards Predictive Material Manufacturing”
May 3 @ 10:00 am - 11:00 am
The long-duration space mission demands a paradigm shift from on-ground to in-space ‘born-certified’ manufacturing because material characterization/testing facilities are simply not available there. This is, however, not trivial due to the lack of an approach of correlating in-space manufacturing conditions with the material microstructure evolution in situ. It remains a challenge using traditional single-scale simulation tool to address the complexity induced by the simultaneous occurrence of microscale plastic flow, nanoscale thermal transport, and atomic-level ion hopping in materials when exposed to stresses, heat pulses, ultrasonic vibrations and even a combination of them in space. To meet this challenge, a massively parallelized concurrent atomistic-continuum (CAC) simulation tool has been developed and will be presented in this talk. Built upon a unified atomistic and continuum description of materials, CAC provides us with a self-consistent description of dislocations, phonons, and diffusion in atomistic and continuum domains within one single model. It thus can predict the microstructure evolution in materials under multi-physical stimuli by considering them as a collection of atoms. As a preliminary demonstration, here we will report its potential in quantifying the processing-structure-property relationship of structural alloys to be fabricated through ultrasonic additive manufacturing in space. The mechanisms underlying the interplay between ultrasonic vibration, microscale plastic flow, nanoscale recrystallization, and atomic-scale interface diffusion in materials will be revealed. A validation of the developed multiscale method through in-situ sensing together with its connections with nanowire-based spacesuit fabrications and multiscale computational fluid dynamics will be also briefly discussed.
Dr. Liming Xiong is currently an associate professor in the Department of Aerospace Engineering at Iowa State University. He earned his PhD and M.S. in the Department of Mechanical and Aerospace Engineering at University of Florida and George Washington University, respectively. His research focuses on the development of a multiscale modeling method and its applications in designing advanced materials for aerospace, mechanical, nuclear, chemical, and civil engineering applications. The method that he has developed attracted attentions and collaborations from both academia and industries nationwide. He authored/co-authored 65 peer-reviewed papers in a variety of different areas. In addition to one NASA project, he is currently leading 4 active NSF projects and serving as a guest editor of two high-rank journals.