Numerical Simulation Analysis and Experimental Research on Damping Performance of a Novel Magnetic Fluid Damper

Wenrong Yang,Xiaorui Yang,Jianzheng Su,Dejie Wei,Qingxin Yang,Luigi Di Sarno

doi:10.1155/2021/6629802

Abstract

Considering the low-frequency and large-amplitude vibration characteristics of the high-rise structure, a tuned magnetic fluid rolling-ball damper is proposed to suppress the vibration of the structure. By adjusting the external magnetic field to control the natural rolling frequency of the ball, the purpose of tuning vibration reduction is achieved. Firstly, the working principle of the damper is theoretically analysed, a three-dimensional (3D) magnetic-fluid-solid multiphysical field coupling mathematical model of the damper is established and the governing equations of multiphysical field coupling are derived. Secondly, the magnetic field distribution and operating characteristics of the damper are simulated and analysed. Finally, the effectiveness of the model is verified by experiments, and the damping performance of the damper with two kinds of magnetic fluid is tested and compared. The results show that the magnetic-fluid-solid multiphysical field coupling model can accurately simulate the working characteristics of the damper. The maximum damping force of the damper is about 12% of the elastic force of the structure, which can increase the damping ratio of the structure by about two times, effectively reduce the vibration response time, and suppress the vibration of the high-rise structure.

Highlights

Ferrofluid, called magnetic fluid, is a kind of colloidal stable liquid composed of magnetic nanoparticles, carrier fluid, and surfactant. e surfactant is coated on the surface of magnetic nanoparticles to prevent the mutual attraction of solid nanoparticles from causing aggregation, and due to Brownian motion, magnetic nanoparticles are uniformly dispersed in carrier liquid [1, 2]
To verify the results of numerical analysis and test the damping performance of the tuned magnetic fluid rollingball damper, a single-layer steel frame structure is used to simulate the single-degree-of-freedom system for the free vibration experiment and harmonic forced vibration experiment. e frame structure is made of 1 mm-thick phosphorous copper plate and the height adjustable range is 300 mm to 500 mm
In this study, based on the vibration characteristics of highrise structure, a tuned magnetic fluid rolling-ball damper is presented to suppress the wind-induced vibration of highrise structure. e multiphysical field coupling analysis of the damper is carried out, and the magnetic–fluid–solid multiphysical field coupling model of the damper is established, which can accurately simulate the working characteristics of the damper

Summary

Introduction

Ferrofluid, called magnetic fluid, is a kind of colloidal stable liquid composed of magnetic nanoparticles, carrier fluid, and surfactant. e surfactant is coated on the surface of magnetic nanoparticles to prevent the mutual attraction of solid nanoparticles from causing aggregation, and due to Brownian motion, magnetic nanoparticles are uniformly dispersed in carrier liquid [1, 2]. Rough the establishment of the magnetic-fluid-solid multiphysical field coupling model of the damper and the simulation study, the working characteristics of rolling ball and magnetic fluid were explored, and the natural sloshing frequency of the damper was theoretically and numerically analysed. Based on the magnetoviscosity characteristic of magnetic fluid, the viscosity of magnetic fluid can be changed by controlling the external magnetic field, and the frictional shear stress between the boundary layer of magnetic fluid and the inner surface of the ball can be changed, so as to control the natural rolling frequency of the ball and change the resonance characteristics of the structure to achieve the purpose of tuning vibration reduction. According to equation (1), after the size of the damper is determined, the natural rolling frequency of the ball can be adjusted by only changing the input current in the induction coil to achieve the purpose of tuning vibration reduction

Multiphysical Field Coupling Mathematical

Experiments and Results

Conclusions