Study On Propagation Characteristics Of Ultrasonic Wave In Magnetorheological Materials

Magnetorheological materials(MRMs) are smart materials. The properties ofMRMs such as mechanical properties, rheological properties, magnetic properties,electrical properties and optical properties have been researched all around the world,especially the mechanical properties and device development, for example themagnetorheological damper device which is widely used in automobiles, machinery andother fields. However, there are just a few literatures about acoustic properties ofMRMs. Therefore, the study of propagation characteristics of ultrasonic wave in MRMsin domestic is not only novel, but also provides inspiration and foundation for the futuredevelopment of new magnetic control ultrasonic devices.Considering the phenomenon that the propagation characteristics of ultrasonic inmagnetorheological fluid(MRF) are significantly influenced under different conditions,the theory of ultrasonic propagation in solid-liquid two phase mixture medium isstudied，and an experimental apparatus is designed and fabricated to study suchpropagation characteristics of ultrasonic in MRMs. In this thesis, the influences ofexternal conditions on the propagation characteristics of ultrasonic are studied.Specifically, it includes:1) The research status of propagation characteristics of ultrasonic in magneticfluids and MRF are analyzed as well as the defects and deficiencies at home and abroad.The background and significance of the subject are expounded, on the basis of whichthe main research content is illustrated.2) The propagation characteristics of ultrasonic in the medium are studied, and theexpression of velocity and attenuation when ultrasonic wave propagation in two-phasemedium is analyzed. The relationship between the acoustic attenuation and velocity insolid-liquid two-phase system is established with the ECAH model.3) The experimental system is designed. The designed experiment device can notonly adjust the size of the magnetic field by changing the current size, but also canchange the size of angle θ which is between the direction of magnetic field andultrasonic. Ultrasonic generating circuit and receiving circuit are designed, andsimulated by ORCAD software. The circuits are used in the experiment aftermanufactured and tested successfully. 4) When magnetic induction intensity range of0-0.2T and the angle θ is0°,30°,60°,90°,120°,150°,180°, propagation characteristics of ultrasonic in MRF andmagnetorheological viscoelastic fluid(MRVF) are studied through the experiments. Thepropagation characteristics are compared when ultrasonic spread in MRF and MRVF.Besides, hysteresis effect exhibited by the modulation magnetic field does on theultrasonic velocity and amplitude is found, and the ultrasonic velocity and amplitudehave the same tend with the magnetic induction intensity when two angles arecomplementary.5) The qualitative interpretations of above-mentioned phenomena are givenaccording to propagation mechanism of ultrasonic in inhomogeneous media as well asthe structure mechanism of MRMs. The magnetic-chain structure formation in MRMschanges when the size and direction of the magnetic field are changed, which leads tothe velocity and amplitude of ultrasonic changing correspondingly. The investigationresult shows that the propagation velocity and amplitude of ultrasonic in MRMs aretightly associated with the strength of chain structures and its orientations, and exhibitapparent hysteresis.