Preliminary investigation of the frictional response of reptilian shed skin

Developing deterministic surfaces relies on controlling the structure of the rubbing interface so that not only the surface is of optimized topography, but also is able to self-adjust its tribological behavior according to the evolution of sliding conditions. In seeking inspirations for such designs...

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Bibliographic Details
Published in:Wear 2012-06, Vol.290-291, p.51-60
Main Authors: Abdel-Aal, H.A., Vargiolu, R., Zahouani, H., El Mansori, M.
Format: Article
Language:English
Subjects:
Anisotropy
Bio-friction
Bio-tribology
Coefficient of friction
Nanostructure
Reptiles
Sheds
Sliding
Snakes
Surface texturing
Tribology
Tribology of skin
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Summary:Developing deterministic surfaces relies on controlling the structure of the rubbing interface so that not only the surface is of optimized topography, but also is able to self-adjust its tribological behavior according to the evolution of sliding conditions. In seeking inspirations for such designs, many engineers are turning toward the biological world to correlate surface structure to functional behavior of bio-analogs. From a tribological point of view, squamate reptiles offer diverse examples where surface texturing, submicron and nano-scale features, achieve frictional regulation. In this paper, we study the frictional response of shed skin obtained from a snake (Python regius). The study employed a specially designed tribo-acoustic probe capable of measuring the coefficient of friction and detecting the acoustical behavior of the skin in vivo. The results confirm the anisotropy of the frictional response of snakes. The coefficient of friction depends on the direction of sliding: the value in forward motion is lower than that in the backward direction. In addition it is shown that the anisotropy of the frictional response may stem from profile asymmetry of the individual fibril structures present within the ventral scales of the reptile. ► The friction profiles of the shed skin are anisotropic. The coefficient of friction exhibits dependence on the direction of sliding. ► Study of the profile of the fibril tips suggest that the observed frictional anisotropy is of geometrical origin. ► Acoustical emission, associated with friction was invariant to the direction of sliding.
ISSN:0043-1648
1873-2577
DOI:10.1016/j.wear.2012.05.015