Vibration isolation using frictional inerters embedded in linkages

This study introduces a novel nonlinear isolator that integrates a tunable inerter within a geometrically nonlinear linkage–spring mechanism and explicitly accounts for the inerter's inherent friction. The isolator is designed to mitigate low-frequency vibration of single-stage systems and flexible-foundation isolation systems commonly found in marine and aerospace engineering. The dynamic responses are calculated using the harmonic balance method (HBM) scheme and verified numerically via the Runge-Kutta (RK) technique. Vibration transmissibilities and power flow metrics are employed to evaluate isolation performance, with experimental validation performed. The results indicate that employing a Jenkins element to model inerter friction yields higher accuracy than the Coulomb and LuGre models by accounting for both energy dissipation and stick–slip effects, thereby better capturing the actual inerter property as shown by experimental observations. When embedded horizontally within the linkage structure, the inerter contributes to low-frequency vibration isolation, outperforming traditional quasi-zero-stiffness configurations in reducing both transmissibility and power flow. Its tunable inertance enables flexible adjustment to different operating conditions. A dynamic interaction between the linkage-spring and the horizontal inerter is identified. With proper parameter tuning, vibration transmission is minimised and effective isolation extends across a wider frequency range, in which the transmissibility is lower than unity. These results offer valuable insights for controlling low-frequency vibrations in practical engineering systems.