Title: Crumpling dynamics and the evolution of damage networks

Author (Talk): Omer Gottesman, Harvard University

Abstract:

When describing the dynamics of a sheet of paper being crumpled one may be tempted to only take the elastic response of the thin sheet into account and consider only those deformations which minimize the elastic energy of the crumpled sheet. However, most materials yield and deform plastically, leaving permanent scars in the thin sheet. Indeed, the simple process of crumpling a sheet of paper with our hands results in a complex network of interconnected permanent creases of many sizes and orientations, along which the sheet preferentially bends. Thereby, history dependence is introduced into the system. I will present an experimental study of the dynamics of crumpling. Specifically, we investigate how a crease network evolves when a thin elastoplastic sheet is repeatedly crumpled, opened up and then re-crumpled. Is there a maximally crumpled state after which the sheet can be crumpled without further plastic deformations? Can the pre-crumped sheet be deformed into a sphere without the creation of new creases and therefore fold rather than be crumpled?

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