Novel smart magnetorheological elastomer vibration controller: experiment, modelling and development

Abstract

Magnetorheological elastomer (MRE) is a new kind of smart material. MRE materials are composed of micro-sized ferromagnetic particles and non-magnetic elastomer. The stiffness and damping properties of MRE can be controlled continuously, rapidly and reversibly by an external magnetic field which makes MRE as an ideal material for vibration control. Currently, the applications of the materials are at an exploratory stage. Challenges include a better understanding of the dynamic behaviour of MRE materials, to accurately and continuously model the dynamic properties of MRE and to use MRE properly in the engineering application.

In this thesis, the dynamic shear and compression mechanical properties of MRE are investigated. Three different MRE samples with 10%, 30% and 50% iron particle concentrations are used for dynamic properties testing. MRE samples are tested at different strain amplitudes, frequencies, magnetic fields and pre-strain amplitudes. The experiment results show that the dependence of the pre-strain is an important parameter that needs to be considered. The new findings are large prestrain amplitude deteriorates the controllability of MRE; coupling effects between pre-strain amplitude and magnetic field, frequency and strain amplitude, strain amplitude and magnetic field on the dynamic mechanical properties are obvious. These coupling effects are considered for modelling the dynamic properties of MRE. Based on the experimental results, a nonlinear mathematical model is proposed to describe the dynamic properties of MRE. The mathematical model considers the dependences of pre-strain, frequency, strain amplitude, magnetic field and their coupling effects. The proposed mathematical model can accurately and continuously model the dynamic shear and compression properties of MRE. A hybrid shear and squeeze MRE based isolator is designed. The MRE isolator is optimised to have a compact size, lower power consumption and high load-bearing capacity. The isolation performance of the hybrid MRE isolator is experimentally and numerically studied. By comparing with the experimental results and simulation results, it is found that the resonance frequencies of the isolation system shifted from 30.1 Hz to 36.8 Hz at a magnetic field of 500 mT. With a simple on-off control, the maximum force transmissibility of the hybrid MRE isolation system is reduced from 6.6 to 3.2 (51.5%).

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ORCID for Yeping Xiong: orcid.org/0000-0002-0135-8464

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