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MEAM Seminar: “Wrinkles, Spaghetti, and Knots”
April 16, 2019 at 10:30 AM - 12:00 PM
Buckling, twisting and fracture are ubiquitous phenomena that, despite having been studied for centuries, still pose many interesting conceptual and practical challenges. In this talk, I will summarize recent theoretical and experimental work that aims to understand the role of curvature and torsion in wrinkle pattern selection, fragmentation cascades and knots. First, we will show how changes in curvature can induce phase transitions and topological defects in the wrinkling patterns on curved elastic surfaces. Thereafter, we will revisit an observation by Feynman who noted that dry spaghetti appears to fragment into at least three (but hardly ever two) pieces when placed under large bending stresses. Using a combination of experiments, simulations and analytical scaling arguments, we will demonstrate how twist can be used to control binary fracture of brittle elastic rods. Finally, in the last part, we will try to shed some light on how topology and torsion affect the stability of knots.
Associate Professor of Physical Applied Mathematics, Massachusetts Institute of Technology
Jörn Dunkel is Associate Professor of Physical Applied Mathematics at MIT. He joined the MIT mathematics faculty in 2013 as an Assistant Professor. Jörn received Diplomas in Physics (2004) and Mathematics (2005) from the Humboldt University Berlin, and completed his PhD at the University of Augsburg (2008). After two years of postdoctoral research at the Rudolf-Peierls Centre for Theoretical Physics in the University of Oxford, he spent three years as a Research Associate at DAMTP in the University of Cambridge. Working at the intersection of statistical and biological physics, Jörn’s current research focuses on how physical properties of individual cells or microorganisms determine self organization, development and biological function in multicellular complexes. To this end, his group is developing and investigating mathematical models that describe dynamical behavior and structure formation in microbial and soft matter systems. Jörn was elected to a Junior Research Fellowship in Physics at Mansfield College, University of Oxford in 2008, and was named Research Fellow at Murray Edwards College, University of Cambridge in 2011. He is the recipient of the 2011 Gustav Hertz Prize of the German Physical Society. In 2015 Jörn was awarded an Alfred P Sloan Research Fellowship and an Edmund F. Kelly Research Award. He received a Complex Systems Scholar Award from the James S. McDonnell Foundation in 2016.