Physics of Nonlinear Mechanics

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Technical SummaryThis award supports theoretical and computational research and education where techniques from statistical and computational physics are applied to a variety of nonlinear problems in the mechanics of solids, mainly but not exclusively involving fracture.Some particular questions to be addressed include: How do cracks choose their direction? What are the fracture properties of graphene? Why does the method of creating graphene with tape work? How does rubber behave when stretched at high rates, and how does this behavior affect fracture? What are the laws of adhesion and friction that govern practical attempts to build optical nanostructures? These questions come from many different subdisciplines of physics and engineering, but are unified by underlying theoretical techniques, by a common set of numerical tools, and by an overarching theme of materials research which seeks to answer: How do macroscopic phenomena follow from microscopic foundations?Parts of this research may have engineering applications. The PI will provide support to instructors around the world after completion of a second edition of a textbook on condensed matter physics. He will complete a textbook for an undergraduate course on how to conduct scientific research. He will use techniques from statistical physics to analyze data from high-stakes public school tests and develop new ways to assess schools and teachers. He will continue to oversee the preparation of science and mathematics teachers at his home institution, as well as a rapidly growing national network of universities replicating the UT Austin program.Nontechnical SummaryThis award supports theoretical research and education with the aim of understanding how the behavior of materials follows from underlying physical laws. In particular, the PI aims to understanding the atomic-scale underpinnings of mechanical behavior, such as how solids stretch, bend, flow, and fracture. One of the outstanding problems in the theory of fracture is how cracks choose which direction to go. The problem is particularly difficult when the cracks are moving fast, and particularly important when the crack is an earthquake that may or may not hit a densely populated area. Some hints at how to proceed come from experiments on the rupture of rubber, and the PI will actively pursue these hints. Another problem concerns the formation of graphene, a promising candidate material for electronic devices of the future. It was first obtained by pulling on graphite with adhesive tape. Why does such a simple process work? Can it be optimized to make very large strips of graphene? The PI will try to answer that.A second part of the proposal concerns education. The PI is just finishing a graduate text on the whole field of Condensed Matter Physics, and will provide supporting materials. He is finishing an undergraduate text on how to conduct scientific research, and will provide supporting materials. He is applying techniques from statistical physics to the analysis of high-stakes test scores, which may influence how these scores are used to evaluate teachers, schools, and districts.