Design, testing and analysis of a pivoted-bar inerter device used as a vibration absorber

In this paper a new design for a small scale inerter-based dynamic vibration absorber (IDVA) is presented, based upon a pivoted-bar mechanism. There are several new innovations in this study. The first is to design, build and test an inerter-based device that does not need to be grounded, or placed between different parts of the structure in order to create relative motion. Instead, the relative motion is created between an auxiliary mass and the host structure. Secondly, the pivoted-bar mechanism is designed to act as a pure inerter, and avoids unbalanced inertance effects such as those that occur in the dynamic antiresonant vibration isolator (DAVI). Thirdly, the effects of parasitic mass are minimised by using (i) the appropriate device arrangements, (ii) numerical optimisation, and (iii) fine tuning of the device by adding small additional masses. Fourth, the optimum device damping values are obtained by using a gel damper that can be modelled as a hysteretic damper. In addition, the design uses frictionless flexure hinges that have a small amount of stiffness that can affect the device performance. It is shown how this can also be compensated for using the design optimisation and fine tuning strategies. Detailed design and analysis methodologies are provided, in order to extend the existing work on inerters towards practical design and implementation. In terms of applications, it is anticipated that the design would be suitable for small-size restricted-space applications. A prototype of the design for a small-scale and relatively high frequency application is manufactured. Experimental and numerical results show that the device provides a 18% improvement in performance compared to a classical tuned mass damper (TMD).