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A Variational Perspective on Wrinkling Patterns in Thin Elastic Sheets: What sets the local length scale of tensile wrinkling?

Robert V. Kohn, NYU, Gergen Lecture
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Wednesday, March 20, 2019
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12:00 pm - 1:00 pm
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Robert V. Kohn (New York University, Courant Institute)
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Math Department presents Gergen Lectures Seminar

The wrinkling of thin elastic sheets is very familiar: our skin wrinkles, drapes have coarsening folds, and a sheet stretched over a round surface must wrinkle or fold.

What kind of mathematics is relevant? The stable configurations of a sheet are local minima of a variational problem with a rather special structure, involving a nonconvex membrane term (which favors isometry) and a higher-order bending term (which penalizes curvature). The bending term is a singular perturbation; its small coefficient is the sheet thickness squared. The patterns seen in thin sheets arise from energy minimization -- but not in the same way that minimal surfaces arise from area minimization. Rather, the analysis of wrinkling is an example of "energy-driven pattern formation," in which our goal is to understand the asymptotic character of the minimizers in a suitable limit (as the nondimensionalized sheet thickness tends to zero).

What kind of understanding is feasible? Read the complete abstract at https://math.duke.edu/events/82667-variational-perspective-wrinkling-patterns-thin-elastic-sheets-what-sets-local-length