Inerter-based vibration control devices with Rhombic Configuration for Apparent Mass Amplification

Inerter-based devices are increasingly investigated for vibration control in dynamic systems, where increasing apparent mass can enhance structural response mitigation without a significant increase in physical weight. This work examines the dynamic behavior and experimental characterization of a mechanical inerter integrated within a rhombic frame, exploiting geometric amplification to boost effective inertance. The device combines a traditional inerter mechanism with a truss-like rhombic arrangement, allowing the inertial forces to be amplified through the kinematic properties of the frame. Such amplification is particularly advantageous when the device interacts with secondary systems, enhancing overall vibration suppression. The study focuses on the relationship between the rhombic geometry and the measured inertance, emphasizing discrepancies observed between classical theoretical predictions and experimental results. Harmonic excitation tests are conducted to evaluate frequency-dependent behavior and refine analytical formulations of the inertial response. Results demonstrate that embedding the inerter in a rhombic frame effectively amplifies the apparent mass, while highlighting nonlinearities and experimental uncertainties that complicate inertance estimation. These findings provide insights for the design and modeling of inerter-based vibration control devices in structural systems, showing the potential of geometric amplification for enhanced performance.