MAE Colloquium: Nathan Barton, Ph.D. (Lawrence Livermore National Laboratory), "Modeling Failure in Ductile Metals under Dynamic Loading"


Kimball Hall B11


ABSTRACT I present results from investigations of microstructural effects on failure of ductile polycrystalline metals. A subset of the computational models make use of a crystal-mechanics-based constitutive model that includes porosity evolution. This formulation includes nucleation behavior that is fully integrated into a robust numerical procedure, enhancing capabilities for modeling small length scales at which nucleation site potency and volume fraction are more variable. Anisotropic crystal response and interactions among the crystals produces heterogeneities that influence damage and failure response, and spatial resolution of the polycrystal allows for investigation of various types of nucleation site distributions. By focusing validation efforts on models that connect directly to experimentally measurable features of the microstructure, we can then build confidence in use of the models for components prepared under different processing routes, with different chemical compositions and attendant impurity distributions, or subjected to different loading conditions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 (LLNL-ABS-664056). BIOGRAPHICAL SKETCH Nathan Barton is the Group Leader of the Materials Modeling and Simulation Group in the Computational Engineering Division, and is the ASC/PEM Strength & Damage program element lead. Nathan earned a BS degree in mechanical engineering from the University of Illinois, graduating summa cum laude in 1996. Nathan’s PhD work was conducted through the Deformation Processes Laboratory at Cornell University, with support from a National Science Foundation graduate fellowship. After completing his PhD, Nathan spent several years at the University of California in San Diego before joining LLNL as a staff member. Nathan’s achievements were recognized in 2015 when he was selected to be among the first cohort to receive the LLNL Director's Early- Mid-Career Recognition Award, and in 2017 when he was named a Fellow of the American Physical Society. Nathan's fields of interest center around computational mechanics of materials; with emphasis on multi-scale methods, crystal plasticity, multi-phase materials and phase transformations, dynamic behavior, large-scale computing, and connections to diffraction based experiments. In addition to his program oversight responsibilities, Nathan remains technically engaged in a variety of activities.