Understanding Symmetry Breaking Instabilities in Crack Propagation
Abstract: Despite their practical relevance and apparent similarities to other instabilities in condensed-matter physics and materials science, dynamical instabilities of propagating cracks remain poorly understood. Instabilities spontaneously break the translation-invariant property of simple planar propagation and generically yield complex crack paths in two and three dimensions. In this talk, I will discuss fundamental progress to understand such instabilities in varied contexts using a theoretical framework that bridges micro and macro scales and offers unique capabilities to predicts arbitrarily complex crack paths without ad hoc path selection criteria. Examples will illustrate how this framework has shed light on long-standing puzzles in materials failure from dynamic instabilities of ultra-high-speed cracks to crack-front segmentation in mixed-mode tensile-shear fracture to crack kinking in biological composites.
Bio: Alain Karma is professor of physics and an arts and sciences distinguished professor at Northeastern University since 1988. He received his PhD degree in physics from the University of California, Santa Barbara, in 1985 and was a Weingart Fellow in theoretical physics at the California Institute of Technology from 1985 to 1988. His research focuses on the development of phase-field models of interface dynamics for a broad range of materials science applications, including alloy solidification, dealloying, grain-boundary migration, nanocrystalline growth, and fracture. His awards include the Condorcet Chair from École Normale Supérieure (2004); Northeastern University Klein Lectureship (2006); American Physical Society Fellow (2007); The Minerals, Metals and Materials Society Bruce Chalmers Award (2008); and the Institute of Materials, Minerals and Mining John Hunt Medal (2016).
All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.