Page 50 - Tribology in Machine Design

Basic principles of tribology 37

Thus, eqn (2.72) becomes

and finally

Thus, the fractional film defect of the compounded lubricant is given by

Following the same argument as in the case of the simple lubricant, it is
possible to relate the fractional film defect for both (a) and (b) to the heat of
adsorption, £ c,
for additive (a)

2.11.4. Load sharing in lubricated contacts

The adhesive wear of lubricated contacts, and in particular lubricated
concentrated contacts, is now considered. The solution of the problem is
based on partial elastohydrodynamic lubrication theory. In this theory,
both the contacting asperities and the lubricating film contribute to
supporting the load. Thus

where W c is the total load, W s is the load supported by the lubricating film
and W is the load supported by the contacting asperities. Only part of the
total load, namely W, can contribute to the adhesive wear. In view of the
experimental results this assumption seems to be justified. Load W
supported by the contacting asperities results in the asperity pressure p,
given by

The total pressure resulting from the load W c is given by

Thus the ratio p/p c is given by

where Fi(d ea*) is a statistical function in the Greenwood-Williamson