| Autor: |
Johnson, A. D. G., Strangwood, M., Otto, S. R. |
| Předmět: |
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| Zdroj: |
Engineering of Sport 5, Volume 2; 2004, p10-16, 7p |
| Abstrakt: |
The compression moulding of the polybutadiene core of most multi-piece golf balls results in a material in a metastable state, which can possess spatially non-homogeneous properties. The cores of three commercial two-piece golf balls were characterised by Shore D hardness and cross-link density (through swell ratio determination in toluene) in the as-received condition and after artificial ageing at 60°C for up to 1600 hours. The balls showed a radial variation in hardness and cross- linking with the centre being softer than the edge; softer cores were seen in the 'distance' ball and harder cores in the 'spin' balls. The 'spin' or 'distance' nature of the ball was characterised by their coefficient of restitution (CoR) in normal impact. CoR was found to decrease with increasing incident speed, whilst increasing with ageing and increasing temperature (particularly after ageing). The variation in CoR was partially explained by variation in core shear modulus with cross-linking, but the largest CoR variation occurred for the ball, whose core showed least hardening and extra cross-linking and vice versa. Thus, prediction of ball performance (CoR) cannot be modelled solely on average core properties, but must include the cover and the spatial nature of core properties. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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