Dry friction of microstructured polymer surfaces inspired by snake skin

Abstract

SummaryThe microstructure investigated in this study was inspired by the anisotropic microornamentation of scales from the ventral body side of the California King Snake (Lampropeltis getula californiae). Frictional properties of snake-inspired microstructured polymer surface (SIMPS) made of epoxy resin were characterised in contact with a smooth glass ball by a microtribometer in two perpendicular directions. The SIMPS exhibited a considerable frictional anisotropy: Frictional coefficients measured along the microstructure were about 33% lower than those measured in the opposite direction. Frictional coefficients were compared to those obtained on other types of surface microstructure: (i) smooth ones, (ii) rough ones, and (iii) ones with periodic groove-like microstructures of different dimensions. The results demonstrate the existence of a common pattern of interaction between two general effects that influence friction: (1) molecular interaction depending on real contact area and (2) the mechanical interlocking of both contacting surfaces. The strongest reduction of the frictional coefficient, compared to the smooth reference surface, was observed at a medium range of surface structure dimensions suggesting a trade-off between these two effects.

Static and dynamic friction of hierarchical surfaces

“…We start with a periodic regular succession of grooves and pawls. This pattern has already been studied both experimentally [20,21] and numerically with a slightly different model [34]. Our aim is therefore to first obtain known results so as to validate the model.…”

“…In general, the purpose of research in bio-inspired materials is to improve the overall properties (e.g., mechanical) by mimicking nature and exploiting mainly structural arrangements rather than specific chemical or physical properties. In this context, nano-and bio-tribology are an active research field in terms of both experiment, theory and simulations [14][15][16][17][18][19][20][21].…”

Numerical investigation of the tribological performance of micro-dimple textured surfaces under hydrodynamic lubrication

“…The benefits of surface texturing and the effects of texturing parameters on tribological performance have been experimentally and theoretically investigated over the past two decades. Experimental investigations by means of friction tests were performed to study the influence of surface texturing on load-carrying capacity, friction forces and the friction coefficient [2–4]. Meanwhile, theoretical models were established to describe the mechanism behind surface texturing to improve the tribological performance of lubricated contacts [5–9].…”

Coupling effect of morphology and mechanical properties contributes to the tribological behaviors of snake scales

“…The insights gained from the investigations of snake epidermis have inspired various design mimicking natural systems (Abdel-Aal and El Mansori, 2011; Abdel-Aal and El Mansori, 2013; Baum et al, 2014a; Baum et al, 2014b; Cuervo et al, 2016; Greiner and Schäfer, 2015; Mühlberger et al, 2015). For instance, it has been suggested that a surface texture resembling the scale microstructures of the Python regius is able to benefit the lubrication of cylinder liners (Abdel-Aal and El Mansori, 2011).…”

“…For instance, it has been suggested that a surface texture resembling the scale microstructures of the Python regius is able to benefit the lubrication of cylinder liners (Abdel-Aal and El Mansori, 2011). The frictional examination on polymer surface with snake-inspired microstructures has revealed that the special ventral surface ornamentation of snakes cannot only lower friction coefficient, but also generate anisotropic friction, which might be another adaptation to sliding locomotion (Baum et al, 2014a; Baum et al, 2014b).…”