Experimental Investigation of an Asymmetric Inerter Nonlinear Energy Sink for Vibration Control

Existing structural control devices such as nonlinear energy sinks (NESs) and tuned mass damper (TMD) have demonstrated outstanding control efficacy. However, they are susceptible to changes in structural frequency or excitation and require a large sliding mass or space for implementation, which impedes their widespread practical application. In this study, an asymmetric inerter (ASYMI) NES is proposed to improve control efficiency and reduce the mass of dampers. Based on a 1:8-scale two-story aluminum alloy frame structure constructed in a laboratory, the ASYMI NES is optimized and experimentally investigated. The structural parameters are identified by conducting free-vibration testing on the uncontrolled structure. In the laboratory, an adjustable inerter is designed using a gear-rack mechanism. Two seismic records are applied to the experimental structure in shaking table experiments to analyze the control effect of the ASYMI NES device under ground motion. The experimental results for a structure equipped with the control device is compared to the simulated data to analyze the reasons for the discrepancies between experimental and simulation results. The results revealed that the RMS and peak errors between the simulation and experimental results were both within 10%. Overall, the ASYMI NES demonstrated impressive control capabilities, even if the stiffness does not reach the optimal design stiffness during our experiments, indicating its strong potential for engineering applications.