Study On Vibration Transfer Characteristics Of Impedance Quasi - Periodic Structure Based On Magnetorheological Fluid

Magnetorheological fluid is a kind of intelligent material,belonging to the category of complex fluid.Under the action of the magnetic field,the particles inside the magnetorheological fluid will change from free distribution to ordered state in the direction of the magnetic field.This structural change causes the physical properties of the magnetorheological fluid(such as rheological properties,damping and impedance,etc.)to change,and this process is reversible.The research shows that the magnetic field can be controlled by adjusting the external magnetic field,so the magnetorheological fluid has a wide application prospect in the field of intelligent vibration control.In this paper,four quasi-periodic structures of magnetorheological fluid resistance are constructed based on the continuous and adjustable impedance of magnetorheological fluid under magnetic field,and the transmission characteristics of elastic wave in four kinds of quasi periodic structures are studied by theoretical modeling,numerical simulation and experimental tests.This article mainly has carried on the following work:Firstly,by analyzing the internal structure of the magnetorheological fluid,aiming at the problem that transition of solid-liquid two-phase morphology of magnetorheological fluid,the transmission characteristics of elastic wave in magneto rheological fluid medium are studied by using Biot theory.And the influence of magnetic field strength and porosity on elastic wave transmission was numerically analyzed by Matlab software.The results show that the magnetic field strength and the porosity of the magnetorheological fluid can increase the attenuation effect of the elastic wave.Secondly,in order to analyze the transmission properties of quasi periodic structure,the equivalent transfer model of of magnetorheological fluid when zero field and magnetic field effect were constructed.Taking the inverse quality factor as the evaluation index,the feasibility of the equivalent transfer model is verified by comparing with the Biot model.Then,based on the equivalent transfer model,the transfer matrix of the basic unit of the quasi periodic structure(the uniform impedance and the continuous change of the impedance)were derived by using the theory of elastic dynamics and layered discretization.Then,based on the transfer matrix of the basic unit of the quasi-periodic structure,the transfer models of Fibonacci,Cantor,Thue-Morse and Double-periodic quasi-periodic structures were constructed respectively,and the transmission characteristics were analyzed by Matlab.The results show that with increase of frequency and magnetic field intensity,the attenuation effect of elastic wave of four kinds of quasi periodic structure are enhanced;compared with magnetorheological fluid structure in zero field effect,quasi periodic structure have better effect on attenuation of elastic wave.Finally,the experimental platform of the quasi-periodic structures based on magnetorheological fluids was built.The transmission characteristics of elastic wave in Fibonacci,Cantor,Thue-Morse and Double-periodic quasi-periodic structures based on magnetorheological fluids were studied by using vibration level as the evaluation index.The results show that with the increase of magnetic field strength and frequency,the attenuation of elastic wave of Fibonacci,Cantor and Thue-Morse and Double-periodic quasi-periodic structure are enhanced.When the thickness and magnetic field are the same,the vibration attenuation effect of Thue-Morse quasi-periodic structure is the best.The experimental results are in good agreement with the theoretical results,which verifies the correctness of the theoretical model.