Contact instabilities of anisotropic and inhomogeneous soft elastic films

Gaurav Tomar and Ashutosh Sharma
Phys. Rev. E 85, 021603 – Published 15 February 2012

Abstract

Anisotropy plays important roles in various biological phenomena such as adhesion of geckos and grasshoppers enabled by the attachment pods having hierarchical structures like thin longitudinal setae connected with threads mimicked by anisotropic films. We study the contact instability of a transversely isotropic thin elastic film when it comes in contact proximity of another surface. In the present study we investigate the contact stability of a thin incompressible transversely isotropic film by performing linear stability analysis. Based on the linear stability analysis, we show that an approaching contactor renders the film unstable. The critical wavelength of the instability is a function of the total film thickness and the ratio of the Young's modulus in the longitudinal direction and the shear modulus in the plane containing the longitudinal axis. We also analyze the stability of a thin gradient film that is elastically inhomogeneous across its thickness. Compared to a homogeneous elastic film, it becomes unstable with a longer wavelength when the film becomes softer in going from the surface to the substrate.

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  • Received 24 November 2011

DOI:https://doi.org/10.1103/PhysRevE.85.021603

©2012 American Physical Society

Authors & Affiliations

Gaurav Tomar1,* and Ashutosh Sharma2

  • 1Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560 012, India
  • 2Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208 016, India

  • *gtom@mecheng.iisc.ernet.in

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Vol. 85, Iss. 2 — February 2012

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