Use of Inerter-based Vibration Absorbers for Suppressing Multiple Cable Modes

A common approach to the mitigation of vibrations of structural cables, e.g. on cable-stayed bridges, is to install a viscous damper transverse to the cable axis quite close to one end. The damping coefficient can be optimized for suppressing vibrations in one cable mode but the damper is then sub-optimal for other modes. This paper proposes the use of a passive inerter-based vibration absorber for suppressing multiple unwanted cable vibration modes. The inerter has the property that the force between its two terminals is proportional to their relative acceleration. A previous study has shown that inerter-based vibration absorber configurations can provide greater modal damping ratios than a viscous damper alone for vibration modes around the first undamped natural frequency. In this study, a finite-element model of a taut cable, together with a generic absorber is built. The absorber is located close to one end of the cable and represented by a general positive-real impedance function. The absorber layouts for maximizing the modal damping ratios over lower-frequency modes while perverting deterioration those for higher-frequency modes are identified. It will be shown that, compared with traditional viscous dampers, the proposed inerter-based vibration absorbers can give enhanced damping performance over multiple modes.