Seminar: Nicholas Zabaras

Materials Process Design and Control Laboratory Sibley School of Mechanical and Aerospace Engineering, Cornell University

Uncertainty Quantification in Multiscale Deformation Processes

Thursday, January 19, 3:00 PM
Room 823 Benedum Hall

 

Abstract: We will introduce and discuss several problems relevant to predictive multiscale deformation processes. Starting with a material point, we will address methods for quantifying uncertainty in polycrystal microstructures and computing the probability distribution of the observed macroscale properties. We will emphasize mechanical properties including fatigue indicator parameters for superalloys. The mechanical response and properties of a deformed workpiece are sensitive to the initial microstructure associated with each macropoint. Microstructures are random in nature and location-specific. This location-dependence dramatically increases the dimensionality of the stochastic input (curse of dimensionality). To quantify and capture the propagation of uncertainty in multiscale deformation processes, a data-driven bi-orthogonal decomposition strategy is introduced. The multiscale random field representing the random microstructure is decomposed into a few modes in different (macro and meso) scales, simultaneously. As a result, the stochastic input complexity is remarkably simplified. An example of a multiscale forging problem is provided to show the merit of this methodology and to study the effects of uncertain initial grain size distribution and texture on the macroscopic properties. In closing, we will briefly introduce a number of upcoming directions in predictive materials modeling including graph-theoretic approaches.

BIO: After completing doctoral work in Theoretical and Applied Mechanics, Professor Zabaras joined the faculty of the Mechanical Engineering Department at the University of Minnesota, Minneapolis, MN. He became a Cornell faculty member in 1991. Zabaras is a Fellow of the American Society of Mechanical Engineers, and member of the American Physical Society, the American Academy of Mechanics, the Society for Industrial and Applied Mathematics and the Minerals, Metals & Materials Society. He received a Presidential Young Investigator Award from the National Science Foundation in 1991.