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Numerical Study of Forced Vibration Suppression by Parametric Anti-Resonance

Pešek L., Šulc P., Půst L.

Archives of Acoustics

2016

Vol. 41, No. 3

527--533

The parametric anti-resonance phenomenon as an active damping tool for suppression of externally excited resonant vibration is numerically studied herein. It is well known fact that the anti-resonance phenomenon, i.e. the stiffness periodic variation by subtractive, combination resonance frequency, brings stabilization and cancelling into self-excited vibrations. But this paper aims at a new possibility of its application, namely a damping of externally excited resonant vibration. For estimation of its effect we come both from a characteristic exponent of the analytical solution and numerical solution of forced vibration of 2DOF linear system with additional parametric excitation. The amplitude suppression owing to the parametric anti-resonance is studied on several parameters of the system: a depth of parametric excitation, mass ratio, damping coefficient and small frequency deviations from the parametric anti-resonance.

Active Damping of Stick-Slip Self-Excited Vibration for Selected External Excitation Frequencies

Ryczek B., Bogacz R.

Machine Dynamics Problems

2002

Vol. 26, No. 1

35-42

There are numerous possibilities of active control of vibration in mechanical systems. Nevertheless, a very limited number of them can be applied to self-excited systems. This paper presents mechanisms for the generation of stick-slip self-excited vibration of the system with a relatively complicated, history dependent friction mode. The system is additionally influenced by an external harmonic excitation. The experimentally identified friction model enables the description of various cases of stationary and transient motion. For the majority of parameters the values of the external excitation, the amplitude of the system motion is greater than without it. But according to the theory, for the particular frequency of the external excitation, it is possible to minimise the amplitude more than twice. A discussion on the appropriate choice of excitation frequency is given in the paper.