Mechanics of Self-Similar Hierarchical Adhesive Structures Inspired by Gecko Feet - Structural Interfaces and Attachments in Biology - page 215

adhesion, we showed that strong elastic anisotropy allows the adhesion strength to
vary strongly with the direction of pulling. This orientation-dependent pull-off
force enables robust attachment in the stiff direction of the material to be released
by pulling in the soft direction. This strategy can be summarized as “stiff-adhere,
soft-release.”
The complex hierarchical structures in biology provide a rich source of
inspirations for physical sciences and industrial applications. The concepts
discussed in this chapter should be of general value in understanding biological
attachment devices and the design of synthetic adhesive systems in engineering
(e.g., [ 29 , 36 , 52 , 53 ]). While we usually do not expect to capture all of the
bio-complexities in simple models, it is often important to break a complex problem
into many comprehensible sub-problems that can be understood using mechanics
principles. Here we have considered the effects of hierarchical energy dissipation
and elastic anisotropy on robust and releasable adhesion. Many other important
aspects of the problem, such as viscoelasticity and large nonlinear deformation,
have not been taken into account. Much further work will be needed to advance our
current understanding of bio-adhesion mechanisms. The studies on such problems
should be of interest not only to the mechanics community but also to a variety of
other disciplines, including materials science, biology, and nanotechnology.

Acknowledgements The authors gratefully acknowledge stimulating discussions on biological
adhesion systems with many colleagues including K. Autumn, E. Arzt, B. Chen, Q.H. Cheng, L.M.
Dai, R. Fearing, R.J. Full, S. Gorb, P. Guduru, A. Jagota, C.Y. Hui, K. Kendall, R. Spolenak, Z.L.
Wang, Z.Q. Zhang, and Y.W. Zhang. HY acknowledges helpful discussions with Dr. Patrick Klein
on the FEM simulations using Tahoe. Support of this work has been provided by the Max Planck
Society, Brown University, the A*Star VIP Program in Singapore, the National Natural Science
Foundation of China (11072273), and the Program for New Century Excellent Talents in China.

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Uber die Ber

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