You're invited to a seminar with Dr. Shuai Shao, an Associate Professor of Mechanical Engineering at Auburn University, titled "Understanding the High Cycle Fatigue of Additively Manufactured Metallic Materials."

Abstract: The uncertainties surrounding the fatigue, especially high cycle fatigue (HCF), of additively manufactured (AM) metallic materials have been a major roadblock for their adoption in the safety-critical, structural applications. Even in the fully machined and polished condition, the HCF life of these materials is not only often inferior to their wrought counterparts but also exhibits significantly more scatter, making the prediction of fatigue life a challenge. This behavior originates from the unique micro-/defect-structural characteristics of AM materials, strongly influencing the initiation of fatigue cracks, which constitutes a major fraction of the total life. While many reports in the literature highlight the detrimental role of volumetric defects, including gas-entrapped pores, key holes, and lack-of-fusion defects, the fatigue of AM materials is much more complex. On one hand, the fatigue failure of certain AM materials in machined surface condition, such as Ti-6Al-4V, can almost always be traced back to one or a group of volumetric defects. On the other hand, the fatigue crack initiation of some other AM alloys, such as Inconel 718, is known to be less sensitive to the presence of defects. For defect-sensitive materials, the size, shape, and location of volumetric defects may, to a large degree, dictate the initiation of fatigue cracks and therefore the fatigue life. For defect-insensitive ones, fatigue failure is often seen to initiate from microstructural features, such as those leading to the operation of persistent slip bands. Accordingly, this talk is divided into two parts and presents knowledge recently generated by the National Center for Additive Manufacturing Excellence (NCAME) regarding the HCF behavior of these two material classes, with emphasis on Ti-6Al-4V and Inconel 718.

Biography: Dr. Shuai Shao received his Ph.D. in Mechanical Engineering from Washington State University in 2012. He worked in the Los Alamos National Laboratory as a post-doc for over three years after graduation. In Feb 2016, Dr. Shao joined the Center for Advanced Vehicular Systems (CAVS) at Mississippi State University as a post-doc, where he acquired his current research interest in additive manufacturing. In Jan 2017, he joined the Department of Mechanical and Industrial Engineering of Louisiana State University as an assistant professor. Since Fall 2019, he has been an Associate Professor and subsequently a tenured Associate Professor of Mechanical Engineering at Auburn University, where he is also a core faculty member of NCAME. Dr. Shao’s overall research theme concerns with understanding the role of generalized defects (including both manufacturing-induced and crystallographic) in the deformation and degradation of metallic materials, especially the ones fabricated via advanced manufacturing technologies. Over his academic career of 6 years, he has authored/co-authored 100+ peer-reviewed articles in prestigious journals and book chapters, which have resulted in 3600+ citations. He has been actively organizing scientific symposia at international conferences including TMS, MS&T, and ASTM ICAM. He has served/is serving as the PI and Co-PI of multiple research projects funded by DOE, NASA, NSF, DOD, NIST, and FAA. Most of his research activities focus on understanding and modeling synergistic effects of microstructure and defects on the deformation and degradation of additively manufactured metallic materials. He has been privileged to serve on the proposal review panels and as a reviewer for several national and international agencies, including NSF, Swiss National Science Foundation, and Austrian Science Fund. Notable awards won by Dr. Shao include “2023 Auburn Alumni Engineering Council Research Awards for Excellence (Senior Category)”, “2020 ASTM Additive Manufacturing Young Professional Award”, “2019 LSU Mechanical Engineering Outstanding Teacher Award”, and “2019 LSU Alumni Association Faculty Research Award.”