Geometry underlies the mechanical stiffening and softening of an indented floating film
arXiv:1804.02421 · doi:10.1039/D0SM00250J
Abstract
A basic paradigm underlying the Hookean mechanics of amorphous, isotropic solids is that small deformations are proportional to the magnitude of external forces. However, slender bodies may undergo large deformations even under minute forces, leading to nonlinear responses rooted in purely geometric effects. Here we study the indentation of a polymer film on a liquid bath. Our experiments and simulations support a recently-predicted stiffening response [Vella & Davidovitch, Phys. Rev. E 98, 013003 (2018)], and we show that the system softens at large slopes, in agreement with our theory that addresses small and large deflections. We show how stiffening and softening emanate from nontrivial yet generic features of the stress and displacement fields.
arXiv comment22 pages, 14 figures (including SI)
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