Theoretical and experimental investigation on an improved rack and pinion inerter

Abstract

In recent years, inerter-based vibration absorbers have gained popularity in structural control, offering enhanced structural dynamic performance against dynamic events. In this context, this study focuses on the theoretical and experimental investigation of the dynamic behavior of a novel improved inerter with amplified inertance. This improvement involves integrating a traditional inerter device into a rhombus truss structure composed of rigid rods interconnected by hinges. Specifically, the inerter is connected to the extremities of one diagonal of the rhombus truss and is activated by the movement of an excitation source along the opposite diagonal. This configuration exploits the geometrical amplification effect, dependent on the diagonal ratio of the rhombus truss, to enhance inertial properties, resulting in greater inertance values and improved control performance. To characterize the dynamic behavior of the proposed improved inerter, this study first examines a scale model of a traditional inerter without the rhombus frame to establish its inertance characteristics. Next, the improved version of the rack and pinion inerter is experimentally analyzed under sinusoidal excitations with varying amplitudes, considering two configurations: one that replicates classical inerter behavior without amplification and another that amplifies the inertance. Theoretical models for all prototypes are introduced, and comparisons between measured and theoretical inertance are conducted to verify the reliability of theoretical models in accurately predicting inertance and provide insights into the behavior of inerter-based systems and their potential applications in structural control.