Anisotropic friction of rugby ball surfaces

作者：Fuss Franz K^*; Troynikov Olga

来源：Proceedings of the Institution of Mechanical Engineers - Part J: Journal of Engineering Tribology , 2012, 226(J7): 608-615.

DOI：10.1177/1350650112439163

• Rugby balls
• pimpled surfaces
• coefficient of friction
• directional friction
• surface roughness

In irregular, isotropic surface patterns with randomly distributed roughness elements, the kinetic coefficient of friction is expected to be independent of sliding direction. In regular, anisotropic surface patterns, at least two directions are expected to have different friction coefficients. Five different tackified rugby ball surfaces with different pimple heights and densities were tested; three with irregular (two directions at right angles tested) and two with regular patterns (four directions at 45 degrees angles tested). The friction coefficient and the surface height profile were obtained in a standardised way with the Kawabata friction testing equipment. The average friction coefficients found ranged from 0.94 to 1.25. In the irregular patterns, only one exhibited a significant difference between the two perpendicular directions. In one regular surface, the difference between friction coefficients in two main directions was unexpectedly significant, in the other regular surface, an expected difference in friction coefficient turned out to be non-significant. The coefficient of friction correlated highly with roughness parameters, positively with the arithmetic mean roughness and the average slope of the roughness elements, and negatively with the kurtosis. About 18.3% of the coefficient of friction is accounted for uniquely by the arithmetic mean roughness, 46.1% by a combined contribution of the arithmetic mean roughness and the kurtosis and 0% by unique contribution of the kurtosis.

• 出版日期2012-7