Erratum to: Tribol Lett DOI 10.1007/s11249-014-0302-7

During typesetting conversion, an expression was incorrectly edited in the list of notations of the above article. L, the Moes dimensionless parameter, should read as follows:

$$ L = G\root{4}\of {U} $$

The publisher would like to apologize for any inconvenience caused.