Assessing the effect of nonlinearities on the performance of a tuned inerter damper

Abstract

SUMMARYIn this paper, the use of a tuned inerter damper (TID) as a vibration absorber is studied numerically and experimentally, with civil engineering applications in mind. Inerters complete the analogy between mechanical and electrical networks, as the mechanical element equivalent to a capacitor and were developed in the 2000s. Initially, inerters were used for applications in automotive engineering, where they are known as J-dampers. Recently, research has suggested that inerter-based networks could be used for civil engineering applications, offering interesting advantages over traditional tuned mass dampers. In the civil engineering context, research has been mainly theoretical, considering ideal inerters. Because the dynamics of an inerter device include nonlinearities, especially at the low frequencies associated with civil engineering applications, the performance of the TID device using an off-theshelf inerter has been experimentally tested in the work presented here. The chosen system, comprising a host structure with a TID attached to it, was tested using real-time dynamic substructuring (RTDS) or hybrid testing. The inerter was tested physically, while the remaining components of the TID device, the spring and damper, together with the host structure, were simulated numerically. Displacements and forces at the interface between numerical and physical components are updated in real time. This numerical-physical split allows the optimisation of the TID parameters, because the values of the spring and the damper can be changed without altering the experimental setup. In addition, this configuration takes into account the inerter's potentially complex dynamics by testing it experimentally, together with the characteristics of the host structure. Developing RTDS tests for physical inertial substructures, where part of the fed back interface forces are proportional to acceleration, is a challenging task because of delays arising at the interface between the experimental and the numerical substructures. Problems associated with stability issues caused by delay and causality arise, because we are dealing with neutral and advanced delayed differential equations. A new approach for the substructuring algorithm is proposed, consisting of feeding back the measured force deviation from the ideal inerter instead of the actual force at the interface. The experimental results show that with appropriate retuning of the components in the TID device, the performance in the TID incorporating the real inerter device is close to the ideal inerter device.

Optimal tuned mass-damper-inerter (TMDI) design for seismically excited MDOF structures with model uncertainties based on reliability criteria

“…The constant of proportionality is termed “inertance” and is measured in mass units (kg). Notably, several different inerter prototypes were devised and experimentally tested over the past decade achieving inertance values orders of magnitude larger than the devices' physical mass, while observing a linear behavior within relatively wide frequency bands of practical interest . These devices are relatively small‐scale tailored for and used in vehicle suspension systems.…”

Experimental and numerical studies of a novel asymmetric nonlinear mass damper for seismic response mitigation

“…For example, TMD was designed to have adjustable stiffness by changing its pendulum length; shape memory alloy springs were employed in TMD to adjust its stiffness property; a certain degree of nonlinearity in TMD stiffness was explored by connecting a spring to a rotating mass or inserting a very small gap between the TMD and the primary mass . In parallel with the studies of adjustable stiffness in TMDs, some methods to adjust the TMD mass and damping have also been studied . To achieve these targets, however, these adaptive TMDs further complicated the configurations, required temperature‐sensitive materials, or were only applicable to specific control situations.…”

Performance‐based seismic design of tuned inerter dampers

“…All these three systems, the TMD, the TID, and the TMDI, could be installed in multi‐degree‐of‐freedom (MDOF) systems, and due to their setup, they would introduce an additional DOF in the original system. Other configurations involving inerters, such as Ikago et al who introduced a tuned viscous mass damper for civil engineering applications, have been proposed in the literature and are discussed by Zhang et al In addition to the earlier studies demonstrating how TIDs can be designed to improve the behaviour of host structures, such as multistorey buildings or stay cables, TIDs have also been tested experimentally using dynamic substructuring emphasising their feasibility and applicability. Besides civil engineering design applications,() inerter‐based vibration absorbers have been considered in the context of a range of practical applications, such as vehicle suspensions,() train suspensions,() or aircraft landing gears .…”