A passive self-tuning vibration neutraliser

Abstract

This paper proposes a new passive self-tuning vibration neutraliser, which contains a mass, a spring, a lever, a lever fulcrum and a passively self-tuning device. The mass and spring are connected to the two ends of the lever. The other end of the spring is attached to the primary structure. The effective stiffness and mass are dependent upon the position of the fulcrum, which is self-tuneable passively based on the primary structure response. A self-tuning rule is defined for the working of the passively self-tuning device. Specifically, the position of the fulcrum (or the lever ratio) stays unchanged when the displacement of the primary structure is less than a prescribed threshold. Otherwise, the self-tuning device will be kept triggered until an appropriate position of the fulcrum is researched and consequently the displacement is less than the threshold. The self-tuning device is essentially a passive feedback-control system, requiring no sensors, actuators, and external energy. Such a passive self-tuning vibration neutraiser is designed and constructed. Theoretical analyses reveal that a zero can be assigned at the excitation frequency over a broad range to a frequency response function of the primary structure coupled with the proposed neutraliser. It is demonstrated numerically and experimentally on a simply supported beam that the proposed neutraliser exhibits highly-effective, robust and broad-bandwidth performance in control.