Advances in Modeling and Simulation of Micromechanical Response of Materials, with an Emphasis on 3-D Microstructure

Friday, Nov. 20, 2015, 3:00 pm

Mechanical Engineering
Distinguished Seminar Series
Sidney & Marian Green Classroom
(3550 MEK – Mechanical Engineering Kennecott Bldg.)
Reception to follow at 4:00 pm

A. D. (Tony) Rollett, Ph.D.
Department of Materials Science & Engineering
Carnegie Mellon University
Pittsburgh, PA

Abstract: There have been substantial advances in modeling and simulation of microstructure in 3-D. These have been accompanied by equally significant advances in characterization techniques, with serial sectioning, synthetic microstructure generation and synchrotron radiation all contributing strongly. Image-based methods for solving elastic, viscoplastic and elasto-viscoplastic problems are now available to complement finite element methods. The image-based methods sidestep the difficulty of generating meshes that conform to 3-D microstructures while preserving mesh quality. The FFT-based simulations originated by Pierre Suquet and Ricardo Lebensohn provide an example. The resolution available permits many aspects of heterogeneity in deformation to be investigated.  Materials can also be orientation mapped non-destructively in 3-D thanks to penetrating radiation at synchrotrons, which permits microstructural evolution to be characterized. High Energy X-ray Diffraction Microscopy (HEDM) is a prime example of this approach. Synthetic microstructure generation with tools such as Dream.3D now includes distributions of orientation, grain boundary character and grain morphology, even fitting the tails of distributions.  Examples are given of 3-D printed metals, 3-D studies of twin creation during grain growth as it affects grain boundary engineering (GB-E), experiment-simulation comparisons of mechanical twinning in Zr, orientation change and gradients in tensile tests of copper, fatigue crack initiation in superalloys, spatially varying strain and orientation gradients in steel, and tin whisker formation.

Bio: After serving as the department head, 1995-2000, Dr. Rollett is currently a professor in the Department of Materials Science & Engineering at Carnegie Mellon University in Pittsburgh, PA. He received his M.A. in metallurgy & materials science from Cambridge University, UK, in 1976 and his Ph.D. in Materials Engineering from Drexel University, Philadelphia, PA in 1987. Prior to Carnegie, he was the Deputy Division Director, Materials Science & Technology Division at Los Alamos National Laboratory. Rollett is the recipient of numerous honors: Cyril Stanley Smith Award, TMS, 2014; Chercheur d’Excellence (Outstanding Researcher) at the University of Lorraine, Metz, France, 2012; Brahm Prakash Professor at the Indian Institute of Science (Bangalore). 2011, Fellow of TMS, 2011; Fellow of the Institute of Physics (UK), 2005; Howe Medal for Best Paper in Metallurgical Transactions A, 2004; Fellow of ASM-International, 1996; Award for Technology Transfer from the Federal Laboratories Consortium, 1989. His current research program emphasizes quantification of microstructure, especially in three dimensions, and its impact on properties and processing using both computational and experimental techniques.

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