Smart Base Isolator Based On Magnetorheological Elastomer And Performance Test

As a stiffness variable smart material, magnetorheological elastomer (MRE) has received lots of attention in recent years. MRE can be made into base isolators to replace traditional rubber bearings in vibration reduction. By adjusting intensity of magnetic field, intelligent control can be achieved rather than passive control. Intelligent control algorithms are always built on the base of an accurate mechanical model and a basic understanding of its mechanical properties. This paper aims at setting up an accurate, effective mechanical model to describe the relationship between the displacement and force of MRE base isolators.Firstly, basic mechanical properties of MRE are studied. The material experiments on mechanical properties are carried out to get relaxation curves and hysteretic loops. Influences by magnetic field, strain amplitude, and frequency have been studied. The results show that there are obvious MR effects, relaxations and nonlinear phenomena.Secondly, phenomenological models, namely five-parameter general Maxwell model, three parameter Kelvin-Voigt model and five parameter fractional derivative model, are set up based on these data to describe the changes in material introduced by magnetic field, strain amplitude, and frequency. All three phenomenological models can express the relationship between share strain and share stress accurately. Among these the five parameter fractional derivative model performs most excellently. The model of base isolator is built on the basis of the five parameter fractional derivative model.Thirdly, design procedures, consisting of mechanical design and magnetic field design, are discussed. The mechanical procedures are built based on existing regulations of base isolator are discussed in the fourth part while the magnetic part takes both theoretical calculation and finite element analysis into consideration.At last, the performance test is carried out to examine the accuracy of the mechanical model and feasibility of the design method. Sinusoidal loads with different amplitude and frequency, sweep loads with different amplitude and random load are applied to the isolator to acquire the force-displacement curves. Comparisons between experiment and calculation are made on force-displacement curves and magnetic field intensity to verify the accuracy of the mechanical model and design procedures.