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Fig. 1. Transverse wrinkles appear in a stretched flat sleeve (a), while no wrinkles occur in a stretched cylindrical sleeve (b). (c) Sketch of the experimental setup and geometry of an open cylindrical shell. (d) Zebra lines (parallel and straight lines) are projected on the surface of tested sample. Wrinkles are smoothed with increasing curvatures kappa=h/r at the same stretching strain epsilon=0.1: (e) kappa=0, wrinkling, (f) kappa=0.001, a coupling behavior of wrinkling and bending, (g) kappa=0.0017 global bending with smooth surface. In three cases, L=10cm, w=5 cm and h=50 μm.
FROM:
Ting Wang (1), Yifan Yang (1), Chenbo Fu (1), Fei Liu (1), Kui Wang (2) and Fan Xu (1)
(1) Institute of Mechanics and Computational Engineering, Department of Aeronautics and Astronautics, Fudan University, 220 Handan Road, Shanghai 200433, PR China
(2) School of Traffic and Transportation Engineering, Central South University, Changsha 410075, PR China
“Wrinkling and smoothing of a soft shell”, Journal of the Mechanics and Physics of Solids, Vol. 134, Article 103738, January 2020, https://doi.org/10.1016/j.jmps.2019.103738
ABSTRACT: Transverse wrinkles usually occur in a uniaxially tensile elastic membrane and will be smoothed upon excess stretching. This instability-restabilization response (isola-center bifurcation) can originate from the nonlinear competition between stretching energy and bending energy. Here, we find a crucial factor, the curvature, which can control effectively and precisely the wrinkling and smoothing regimes. When the sheet is bent, the regime of wrinkling amplitude versus membrane elongation is narrowed, with local wrinkling instability coupled with global bending. There exists a critical curvature, where no wrinkles appear when the value is beyond this threshold. The curvature effects on wrinkling-smoothing behavior have been quantitatively explored by our theories, computations and experiments. The models developed in this work can describe large in-plane strains of soft shells to effectively capture this transition behavior, which build on general differential geometry and thus can be extended to arbitrarily curved surfaces. Our findings may shed light on designs of wrinkle-tunable membrane surfaces and structures.
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