
120 Friction-Induced Vibration and Self-Organization
Barber (1969) observed that the temperature remained constant at a par-
ticular point for a relatively long period and then increased considerably
for a period of a few seconds. A large number of these uctuations were
recorded. This experiment also showed that the normal load was not uni-
formly distributed over the nominal contact area, but rather was concen-
trated into a relatively small area whose location changed every few seconds.
Barber concluded that any non-uniform loading over the surface causes a
corresponding non-uniform generation of frictional heat and the tempera-
ture eld assoc ...