Page 108 - Tribology in Machine Design

94 Tribology in machine design

surface area the real area of contact will be given by

so that for an ideal plastic deformation of the surface, the total load will be
given by

To summarize the foregoing it can be said that the relationship between the
real area of contact and the load will be dependent on both the mode of
deformation and the distribution of the surface profile. When the asperities
deform plastically, the load is linearly related to the real area of contact for
any distribution of asperity heights. When the asperities deform elastically,
the linearity between the load and the real area of contact occurs only where
the distribution approaches an exponential form and this is very often true
for many practical engineering surfaces.

3.9. Representation of Many contacts between machine components can be represented by
machine element cylinders which provide good geometrical agreement with the profile of the
contacts undeformed solids in the immediate vicinity of the contact. The geometrical
errors at some distance from the contact are of little importance.
For roller-bearings the solids are already cylindrical as shown in Fig.
3.13. On the inner race or track the contact is formed by two convex

Figure 3.13