Indentation of ultrathin elastic films and the emergence of asymptotic isometry

Abstract

We study the indentation of a thin elastic film floating at the surface of a liquid. We focus on the onset of radial wrinkles at a threshold indentation depth and the evolution of the wrinkle pattern as indentation progresses far beyond this threshold. Comparison between experiments on thin polymer films and theoretical calculations shows that the system very quickly reaches the Far from Threshold (FT) regime, in which wrinkles lead to the relaxation of azimuthal compression. Furthermore, when the indentation depth is sufficiently large that the wrinkles cover most of the film, we recognize a novel mechanical response in which the work of indentation is transmitted almost solely to the liquid, rather than to the floating film. We attribute this unique response to a nontrivial isometry attained by the deformed film, and discuss the scaling laws and the relevance of similar isometries to other systems in which a confined sheet is subjected to weak tensile loads.

5 pages, close to published version

References in corpus (1)

• The Liquid Blister Test

Cited by in corpus (5)

• Indentation metrology of clamped, ultra-thin elastic sheets
• A sheet on deformable sphere: "wrinklogami" patterns suppress curvature-induced delamination
• Indentation of a floating elastic sheet: Geometry versus applied tension
• Sculpting liquids with ultrathin shells
• A unified geometric framework for axisymmetric thin sheet buckling