Study On Vibration Transfer Characteristics Of Impedance Periodic Structure Based On MRF

With the continuous development of production technology,people put forward higher requirements on the damping.Thanks to the development of smart materials,The study on the vibration transfer characteristics of new smart materials has attracted a lot of scholars’ attention.Magnetorheological fluid(MRF)is the most widely used intelligent material in the field of vibration control,The variable damping force characteristics of MRF are mainly used in the engineering,but little attention has been paid to the impedance characteristics of the fluid.In this paper based on the Biot theory,according to the transient characteristics of MRF under magnetic field,studied the transfer characteristics of vibration in MRF.Construction of MRF periodic structure and the transfer model of vibration in periodic structures is derived.Its main characteristic is that it can adjust the vibration transfer characteristics of MRF by controlling the external magnetic field strength.The main work of this paper is as follows:Firstly,by analyzing the internal structure of MRF,this paper studied the transfer characteristics of vibration.Based on the theory of Biot,the transfer model of vibration in MRF is established,the wave velocity,inverse quality factor and vibration absorption coefficient of the first kind of longitudinal wave and the second kind of longitudinal wave generated in the magneto rheological fluid are calculated,The effects of magnetic field strength,porosity and thickness on the transfer characteristics are studied by numerical simulation.Results show,the increase of magnetic field intensity and porosity will cause the increase of the first wave velocity and the inverse quality factor,and the decrease of the wave velocity and the inverse quality factor of the second wave.The absorption coefficient of the MRF with a certain thickness increases with the increase of magnetic field strength and porosity,and changes with the thickness.Based on the study of the characteristics of the vibration transfer,the possibility of the MRF as a controllable vibration transfer medium is explained.Secondly,based on the Biot theory and the transfer characteristics of multilayer medium,the transfer model of periodic structure is constructed,and the vibration transfer matrix is derived.The vibration level drop and vibration absorption coefficient are calculated,and the effects of the number of cycles,the thickness of the magnetic field and the magnetic field intensity on the vibration characteristics of the periodic structure are studied by numerical simulation.The results show that under the condition of a certain length,the number of cycles determines the vibration transfer characteristics of periodic structures.When the number of cycles is constant,the increase of the thickness of the magnetic field and the magnetic field intensity can increase the vibration level drop of the periodic structure.Then,the experimental device of the magneto rheological fluid periodic structure with the modulation property is set up.The structure of the electromagnet,the impedance tube and the bracket is designed independently,and the interface of the data acquisition system is designed,and the experimental scheme is designed according to the characteristics of the vibration transmission characteristics and the structure of the experimental platform.Finally,according to the experimental scheme,The vibration level drop of single layer MRF and MRF periodic structure was experimentally studied.Compared with the simulation results,the analysis of the experimental data shows that the number of periodic structure,the thickness of the magnetic field and the magnetic field strength of the MRF are consistent with the experimental results.