DATE: Wednesday, November 8, 2017
TIME: 12:00 – 1:00pm
Associate Professor, School of Civil and Environmental Engineering
Cornell University, Ithaca, NY
The prediction of crack growth is one of the most technologically important and scientifically intriguing problems in mechanics of materials. Yet, despite decades of research, a comprehensive understanding of the process has remained elusive. As a quintessential multiscale phenomenon, crack growth is both a chemical and mechanical process, involving interatomic bond breakage driven by long range mechanical stress fields. Thanks to growing supercomputing resources and novel concurrent multiscale modeling techniques that can accurately couple quantum and continuum mechanics modeling domains, crack tip processes in real environments are just now becoming accessible to powerful quantum chemistry approaches such as Kohn Sham Density Functional Theory. The majority of our work in this area has been focused on understanding how surface impurity elements influence the behavior of cracks in aluminum, a material that serves as the base of many technologically important alloys whose fracture response is known to be affected by chemical environment. In this talk, I will review our work on this topic and use it to frame our ongoing work.
Derek has worked on mechanistic models of deformation and failure in metals since the start of his PhD at Johns Hopkins in 2002. After a yearlong Postdoc in the solid mechanics group at Brown, he became an Assistant Professor at Cornell, continuing his investigation into the mechanisms controlling the failure of metals via an ONR Young Investigator Award and a Presidential Early Career Award. His sustained effort in this area allowed for a number of new insights into the physical mechanisms that control the failure of metals, as well as new approaches to overcome challenges associated with atomistic-based modeling. His recent work has involved the use of atomistic simulation to predict the motion of dislocations through fields of solutes, precipitates, and high strength lattices at experimental timescales, using novel approaches pioneered in the biophysics community. Complementary to this, a significant component of his work has involved the study of deformation processes in multielement systems and scenarios not accessible to traditional interatomic potentials.