Global Control of Vibration Using a Tunable Vibration Neutralizer

Abstract

Tunable vibration neutralizers are currently used to control harmonic vibration of structures at the point at which they are attached, and the way in which the characteristics of the neutralizers in#uence their e!ectiveness in this role are reasonably well understood. However, the use of tunable vibration neutralizers to control global vibration of a structure has not been so well explored, and the aim of this paper is to investigate the parameters of the neutralizer that in#uence the control of the vibrational kinetic energy of a structure. It is shown that in general a de-tuned rather than a tuned vibration neutralizer is required at most frequencies, o!ering a sti!ness-like or a mass-like impedance to the structure. However, because this control strategy requires a measure of the global vibration of the host structure, which can be di$cult and/or costly in practice, it is preferable to use a tuned vibration neutralizer. For this to be e!ective it is demonstrated that the tuned neutralizer needs to be appropriately positioned on the structure. If this is the case then such a device can be almost as e!ective as a de-tuned neutralizer over quite a wide range of frequencies. An expression to determine the optimum ratio of the neutralizer mass to the modal mass of the structure is also derived.

Optimal tuning of the tunable translational-rotational dynamic absorbers in global vibration control problems in beams

“…The disadvantage of this method is the possibility of occurrence of the new resonant frequencies in the resulting structure [1,4,7].…”

“…Due to the application in a number of constructions, much attention has been paid to proper selection of parameters of the dynamic vibration absorbers [DVA] -mainly the most common passive tuned mass dampers [TMD] -in beam structures [1][2][3][4][5][6][7][10][11][12]15].…”

“…If it is technically impossible or in the case of distributed loading, an important issue is the correct location of the absorber, especially in the global or non-collocated optimization problems [1,11,13]. To improve the efficiency of vibration reduction there are used systems of tuned mass dampers [MTMD], tuned in the most general case for a single or several resonant frequencies (for broadband excitation) [8][9][10][11]13,14].…”

“…The drawback of such a solution is that there may emerge the new natural frequencies of the resulting structure, depending on the position of absorbers, which coincide with the excitation frequency, so the proper location of the tunable absorbers is very important, the better performance may be also obtained by de-tuning the absorbers [1,4,8].…”

“…The rotational absorbers may significantly improve the vibration reduction because they may be effective even when placed at nodal points of the host structure, where the translational absorbers have no effect; whereas de-tuning may be advantageous by shifting the resonance frequencies beyond the excitation band [1,4].…”