Active Nonlinear Energy Sink Using Integral Force Feedback

Excessive vibrations in mechanical structures can cause many problems such as reducing structural integrity and compromising the commissioning of precise instruments. Tuned mass dampers (TMDs) are often employed to suppress undesirable vibrations. However, they are known to be effective only in a frequency band limited around one vibration mode and to be sensitive to the variation of primary structures. Alternatively, nonlinear energy sinks (NESs) can be used as they do not have a preferential resonance frequency making them more robust and capable of damping multiple resonances. In this paper, the performance of an active nonlinear energy sink (ANES) is investigated, which is realized using a novel integral force feedback controller. Unlike the traditional NES, which is realized by a cubic spring, a dashpot and an inertial mass, the proposed ANES is equivalent to a mechanical system which consists of a cubic root inerter, a dashpot and a linear spring. Because of the full analogy with a mechanical network, the stability of the proposed active system is guaranteed. Although the form of the proposed ANES is different from that of traditional NESs, it is found that the targeted energy transfer phenomenon also occurs with the ANES and the control effectiveness is similar to traditional NESs.