Micro-hysteretic component of rubber friction generated by
harder, apparently smooth track surfaces is studied in this contribution.
Experimental and theoretical results of [6] obtained at
room and elevated temperature suggest that the friction of nitrile
rubber sliding on apparently smooth steel surface may be dominated
by micro-hysteresis. These friction test results, however,
were not compared with similar results taken from the literature.
A possible reason for this is that the little experimental result
available in this category (almost without exception) focuses on
the room temperature behavior only. Here an attempt has been
made to collect and analyze experimental results on microhysteresis
generated by apparently smooth surfaces. In addition,
friction test results of [6] obtained at T¼25 and 80 °C has also been
reanalyzed and compared to literature results. The coefficient of
friction decreased with increasing ambient temperature in all the
cases but the change in friction was drastically different. In other
words, the temperature dependent micro-hysteresis-based explanation
of Mofidi et al. for the temperature dependency of coeffi-
cient of friction is not of universal validity in case of apparently
smooth surfaces. The contribution to the friction from the area of
contact and rubber wear was not analyzed in [6], but due to the
very unfavorable lubrication conditions it seems possible as well
that the friction measured is, at least in part, due to these phenomena.
The present study shows clearly both the weak points of
already existing friction tests and the need for a comprehensive
testing program on the apparently smooth surface generated
hysteretic contribution to rubber friction. Additionally it is found
that none of experimental results discussed here proves the
dominancy of micro-hysteresis for the sliding pair of Mofidi et al.
and the real contribution of micro-hysteresis is likely considerably
lesser than suggested in [6]. All of these prove that the role of
micro-hysteresis is not fully understood for apparently smooth
surfaces.
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