Page 257 - Tribology in Machine Design
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242 Tribology in machine design
influence on the film thickness. The highly viscous fluid passes through the
parallel zone until the pressure and the viscosity get back to normal at the
exit. This means a decrease in thickness of the film. The inlet and exit
regions are effectively independent. They meet at the end of the parallel
zone with a discontinuity in the slope of the surface which is associated with
a sharp peak in the pressure.
6.7. Analysis of line In this section line contact lubrication is presented in a way which can be
contact lubrication directly utilized by the designer. The geometry of a typical line contact is
shown in Fig. 6.5. The minimum film thickness occurs at the exit of the
region and can be predicted by the formula proposed by Dowson and
Higginson for isothermal conditions
where G = a£ is the dimensionless material parameter, K=[/i 0
(V, + V 2)~\/2ER is the dimensionless speed parameter, W=w/ERL is the
dimensionless load parameter, a is the pressure-viscosity coefficient based
Figure 6.5