Avoidance of Stick‐Slip Motion by Vibration Control

Abstract

This paper deals with the excitation mechanisms of friction induced vibrations and recently found methods to avoid these vibrations. It is remarkable, that mechanisms of excitation and avoidance are closely related and, infact, the presented idea and realization of vibration control is derived from theoretical investigation of excitation mechanism. The basic mechanism will be explained and two methods of vibration control will be demonstrated theoretically and by experiment. The concept of fluctuating normal forces is the basic idea behind the two methods of vibration control. In the first case the fluctuating normal forces are generated by an additional oscillator connected to the basic stick‐slip oscillator. In the second case, fluctuating normal forces are generated directly by a magnetic actuator.

Experimental and numerical analysis of stick-slip suppression with the use of longitudinal tangential vibration

“…The obtained by them experimental tests results indicate that the level of reduction of the stick-slip vibration amplitude by introducing normal vibrations depends on the type of the friction pair material, amplitude and frequency of forced vibration, as well as relative humidity of the environment. Neubauer et al (2005) and Popp and Rudolph (2003;2004) described the possibility of stick-slip reduction by active control of normal to the contact surface vibrations using a normal force with a variable amplitude.…”

Gyroscopic Stabilization

“…The motion of the system sustains itself, an effect which is called self-excitation or self-induced vibration. The reason behind this effect is the presence of negative damping, which results for example from dry friction, see [1], [5], [18]. Another example is the Van der Pol Oscillator (see [13], p. 9), which due to a non-constant damping coefficient, locally has negative damping.…”