E. Brommundt, FRICTIONAL OSCILLATOR WITH SELF-EXCITATIO N WITH MONOTONICALLY INCREASING COEFFICIENT OF FRICTION, Zeitschrift fur angewandte Mathematik und Mechanik, 75(11), 1995, pp. 811-820
A three degrees of freedom oscillator is suggested, which can develop
self-excited oscillations for a coefficient of friction which grows mo
notonical with respect to the frictional velocity.