MSE Colloquium: Dr. Richard LeSar, Modeling microstructure formation in additive manufacturing
The work in this talk was developed as part a multi-university program focused on designing metallic alloys to take advantage of the unique processing conditions in additive manufacturing (AM) to create materials with specified microstructures. Our part of that effort was to build the requisite multiscale modeling tools to predict those microstructures, which requires models for both alloy solidification as well as for the processing conditions. Specifically, heat transport, melting, solute transport, and fluid flow are modeled at the macroscale via the Lattice Boltzmann method and accounting for laser absorption and Marangoni flow in the melt pool. At the microscale, alloy solidification is modeled using cellular automata models, with temperature and fluid flow boundary conditions passed from the macroscale, enabling the linking of process parameters, melt pool conditions, alloy thermodynamics, and microstructure. We will present results for titanium binary alloys as well as a steel.
Richard LeSar is a professor in the Department of Materials Science and Engineering at Iowa State University. LeSar earned his B.S. In Chemistry from the University of Michigan and his A.M. (Physics) and Ph.D. (Chemical Physics) from Harvard University. After a long stay at the Los Alamos National Laboratory, first as a postdoctoral fellow and then in a variety of research and administrative positions, LeSar departed to Iowa State, at which he has served as Department Chair and as the Lynn Gleason Professor of Interdisciplinary Engineering. LeSar’s research uses computational methods to study the properties of materials, with a long-term interest in multiscale modeling, spanning from electronic structure methods to theoretical mechanics. His current work is focused primarily on the development and application of polycrystal plasticity calculations based on discrete dislocation mechanics, the development of multiscale simulations of additive manufacturing, and an increasing focus on developing new computational environments for multiscale design. He is currently writing the second edition of his textbook, Introduction to Computational Materials Science, published by Cambridge University Press.