title: Ribbon curling via stress relaxation in thin polymer films.
abstract: The procedure of curling a ribbon by running it over a sharp blade is commonly used when wrapping presents. Despite its ubiquity, a quantitative explanation of this everyday phenomenon is still lacking. We address this using experiment and theory, examining the dependence of ribbon curvature on blade curvature, the longitudinal load imposed on the ribbon, and the speed of pulling. Experiments in which a ribbon is drawn steadily over a blade under a fixed load show that the ribbon curvature is generated over a restricted range of loads, the curvature/load relationship can be nonmonotonic, and faster pulling (under a constant imposed load) results in less tightly curled ribbons. We develop a theoretical model that captures these features, building on the concept that the ribbon under the imposed deformation undergoes differential plastic stretching across its thickness, resulting in a permanently curved shape. The model identifies factors that optimize curling and clarifies the physical mechanisms underlying the ribbon's nonlinear response to an apparently simple deformation.
authors.affiliation: Department of Mathematical Sciences, Durham University, Durham DH1 3LE, United Kingdom;
authors.forename: Chris
authors.initials: C
authors.lastname: Prior
authors.affiliation: Département de Physique, Ecole Normale Supérieure, 75005 Paris, France;
authors.forename: Julien
authors.initials: J
authors.lastname: Moussou
authors.affiliation: Department of Mathematical Sciences, Durham University, Durham DH1 3LE, United Kingdom;
authors.forename: Buddhapriya
authors.initials: B
authors.lastname: Chakrabarti
authors.affiliation: School of Mathematics, University of Manchester, Manchester M13 9PL, United Kingdom;
authors.forename: Oliver E
authors.identifier: http://orcid.org/0000-0003-0172-6578
authors.initials: OE
authors.lastname: Jensen
authors.affiliation: Manchester Centre for Nonlinear Dynamics and School of Physics & Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom anne.juel@manchester.ac.uk.
authors.forename: Anne
authors.identifier: http://orcid.org/0000-0003-3342-7388
authors.initials: A
authors.lastname: Juel
keywords: elasticity; mechanics; plasticity; stress relaxation; yield
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