Oppositely oriented series multiple tuned mass dampers and application on a parallel machine tool

Passive vibration control of the parallel machine tool is challenging due to its closely spaced vibration modes and position-dependent dynamics. Owing to the advantages of significant vibration suppression, high robustness, and no need for additional damping materials, the series multiple tuned mass dampers (MTMDs) appear to be an effective solution to this problem but suffer from large-sized structure and significant parasitic vibrations. This paper proposes a novel type of oppositely oriented series MTMDs with a compact structure and minimized parasitic vibrations, with the effectiveness and robustness of the traditional type retained. An analytical model of the parasitic and primary vibrations of the series MTMDs is presented for quantitative geometry design. The dynamics of the actual main structure and the analytical MTMDs are integrated, followed by the parameter optimization and performance evaluation of the MTMDs considering the effect of background vibration modes. The oppositely oriented series dual-mass TMDs are implemented to suppress the machining vibrations of a parallel machine tool. Modal tests indicate that 72.7% amplitude of the target mode is reduced by the series dual-mass TMDs, which shows a 10.8% improvement compared to the SDOF TMD with equal damper mass. A maximum of 70.1% vibration reduction is achieved in slot milling experiments.