
135Friction-Induced Instabilities and Vibrations
friction, this phase difference was approximately 0° and 180° for left- and
right-traveling waves, respectively. Thus, for small friction, ε was somewhat
less than μp*V
0
for a right-traveling wave, and hence, the energy dissipated
at the interface was less than the work done in moving the bodies. This extra
energy was the contributor to the self-excited motion that continues to grow
with time. For a left-traveling wave ε > μp*V
0
, the energy dissipated at the
interface was greater than the work done in moving the bodies, forcing the
left-traveling wave to decay. For larger values of friction, the ...