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Vibration transfer characteristic of gradient-like structure based on magnetorheological fluid

In this paper, a gradient-like structure composed of magnetorheological (MR) fluids is proposed, and its vibration transfer characteristic is studied through the modeling, numerical calculation and experimental test. Under the action of an externally applied magnetic field, the MR fluid exhibits the liquid-solid transformation property: the process of transformation between solid and liquid in fact is the change of vibration-transfer impedance. Therefore, based on this property, the gradient-like structure is constructed by controlling the external magnetic field. Based on the wave equation of one-dimensional elastic wave propagation, the wave equation of elastic wave transfer in the gradient-like structure is established. In order to describe the relationship between the complex shear modulus and Lame constant of MR fluid and magnetic field intensity in the wave equation, the equivalent parameter model of MR fluid is established based on the theory of elasticity and viscoelastic materials. Then, the experimental set-up is built to modify this model through experiments. Afterward, the discretization method of continuous medium and transfer matrix method are adopted to solve the wave equation, and the expression of vibration level drop is obtained. Through the numerical calculation, the trend of vibration level drop varying with the frequency of incident elastic wave and the intensity of magnetic field for the gradient-like structure is obtained. Finally, the vibration transfer characteristic of the gradient-like structure is studied experimentally, and the influence of magnetic field intensity on the vibration transfer characteristic of the gradient-like structure is analyzed. The results show that the numerical results are in good accordance with the experimental results, thereby verifying that the numerical model is accurate. And the gradient-like structure has a better attenuation effect on the elastic wave than the MR fluid under the action of a uniform magnetic field, and has an excellent tunable property as well.