Experimental study, mathematical modelling and dynamical analysis of magnetorheological elastomer materials and structures for vibration control

Abstract

As a smart material, magnetorheological elastomer (MRE) is composed of magnetisable particles dispersed in a non-magnetic medium. Because the mechanical properties of MRE can be continuously, rapidly and reversibly controlled by adjusting magnetic field in a pre-yield regime, there has been increasing research on MRE for mitigation of unwanted vibrations, and yet the application and commercialisation in varies fields are still on a very early stage. Considering the dependence of mechanical properties on strain, frequency and magnetic field the current research on mathematical modelling for MRE is still insufficient to provide guidelines for engineering applications.

In this study, the dynamical properties of MRE were studied by means of shear tests under different driving frequencies (1-80Hz), strain amplitudes (0-6.0%) and magnetic fields (0-500mT). The experimental results have shown that the storage modulus of MRE increases as the frequency increases, but the loss modulus initially increases with frequency (<10Hz) up to a maximum value and then decreases with further increasing frequencies; both the storage modulus and loss modulus decrease with an increase of strain, and they increase with increasing magnetic flux densities until the magnetic saturation occurs. With the full use of gathered information on mechanical property characterisation of MRE, a nonlinear mathematical model is established to describe the complex behaviour of MRE for the dynamical analysis of vibration systems, and a methodology of modelling is proposed for materials to continuously describe the dynamic behaviour in certain region of strain and frequency with a benefit of low requirement for the calculation on parameter identification. A structure of MRE is developed with a high bearing capacity and a good controllability of stiffness to benefit vibration control systems. The dynamical properties of this structure are predicted with the dynamic design and the mathematical modelling, and the results are examined through dynamic tests to validate that the extension of this mathematical model in MRE structures. Furthermore, dynamical analysis is presented for a two-stage vibration isolation system, a vibration absorption system and an isolation system consists of a continuous beam and an MRE isolator to examine the efficiency of MRE absorbers and isolators. Results show that a reduction of the vibration amplitude, the force transmissibility or the power flow transmissibility can be achieved by properly designing dynamical systems and considering the excitation frequency ranges. Comparing with conventional absorbers and isolators, MRE devices can locally and globally improve the performance of vibration control significantly from the perspective of dynamical behaviour, transmissibility or vibratory energy transmission.

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

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