In situ Sensing Methodologies for Powder Blown Laser Directed Energy Deposition Additive Manufacturing

Abstract: Process monitoring is essential for process repeatability and qualification, and for AM components can serve to help qualify the final parts themselves. For powder blown laser DED, mass flow is a crucial parameter whose measurement has proven to be particularly difficult, often with large errors. Similarly, current research approaches for defect detection in AM parts using optical, thermal, and acoustic monitoring have shown promise, but tend to be limited to qualitative assessments rather than quantitative ones. With these challenges in mind, we are working to develop a 4-mechanism sensing approach using coupled acoustic, capacitive, inductive, and piezoelectric techniques with the goal of reducing mass flow measurement errors and eventually measuring the composition of mixed powder flows. We are also developing a magnetic computed tomography system for in-situ quantification of defects and their layer-by-layer evolution, including formation, migration, and annihilation.

Bio: Aaron Stebner works at the intersection of manufacturing, machine learning, materials, and mechanics. Prof. Stebner joined the Georgia Tech faculty as an Associate Professor of Mechanical Engineering and Materials Science and Engineering in 2020. Previously, he was the Rowlinson Associate Professor of Mechanical Engineering and Materials Science at the Colorado School of Mines (2013 – 2020), a postdoctoral scholar at the Graduate Aerospace Laboratories of the California Institute of Technology (2012 – 2013), a Lecturer in the Segal Design Institute at Northwestern University (2009 – 2012), a Research Scientist at Telezygology Inc. establishing manufacturing and “internet of things” technologies for shape memory alloy-secured latching devices (2008-2009), a Research Fellow at the NASA Glenn Research Center developing smart materials technologies for morphing aircraft structures (2006 – 2008), and a Mechanical Engineer at the Electric Device Corporation in Canfield, OH developing manufacturing and automation technologies for the circuit breaker industry (1995 – 2000). He has won numerous awards, including an NSF-Career award (2014), the Colorado School of Mines Researcher of the Year Award (2017), and a Visiting Professor Fellowship from the Japan Society for the Preservation of Science (JSPS, 2019). Stebner serves as a board member of the ASM International Organization on Shape Memory and Superelastic Technologies (SMST) and an international advisory committee member of the International Conference on Martensitic Transformations (ICOMAT). Stebner is an Associate Editor for the journal Additive Manufacturing.

Bio: Zach Brunson is a Research Engineer in Georgia Tech’s Mechanical Engineering department, working with Professor Aaron Stebner at the Advanced Manufacturing Pilot Facility (AMPF). Prior to Georgia Tech, Zach was a graduate teaching fellow and research assistant at the Colorado School of Mines in Golden Colorado where he received his Ph.D. (2021) and M.S. (2019) in Mechanical Engineering studying theoretical and experimental mechanics of inelastic anisotropic and asymmetric materials. Zach received his B.S. (2013) in Mechanical Engineering from the University of Colorado in Boulder Colorado and prior to pursuing a graduate degree, gained experience working as a measurements field engineer in the petroleum industry. Zach’s primary research focuses include sensor development for process monitoring and part qualification in additive manufacturing systems and theoretical and experimental mechanics of materials.

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