Study On Dynamic Response And Quiescence Impact Of Magnetorheological Damper

Magneto-rheological(MR) damper is a damping controllable device with the advantages of structural simplicity, quick response, low power consumption and large dynamic range. It is promising in automotive, civil engineering and national defense industry. The dynamic response is one of the most important characteristics of MR damper, which is significant for the practical effectiveness in applications. In this thesis, the testing method and influence factors on dynamic response of MR damper are discussed, and the impact after a long-term quiescence. The main content of the study is as follows:①The MR fluid and its properties are introduced, and the classical applications of MR damper are described. After the reviewing of the state-of-art on MR damper dynamic response and current driver, the existing problems are summarized, and the main work in this paper is introduced.②Based on flow mode and shear mode, parallel duct model and Bingham fluid model, the damping force formula is derived, and the theoretical relation with piston velocity, applied current is clarified. The dynamic response definition is proposed combining with the actual operational characteristics of MR semi-active suspension, some important points of testing method are studied, and the influence factors of dynamic response is analysed.③The current source features for dynamic response testing of MR damper are pointed out. The current driver is analysed, and the small-signal model of the current driver is built with the load of MR damper. Based on the three-terminal PWM switch model, the related transfer functions are listed. In order to improve dynamic response and eliminate steady-state error, the compensation network is designed based on frequency characteristics. The simulation of the current drive is studied based on Saber.④According to the different excitation signals, two trigger devices for current source are designed combining with the dynamic response of auto MR damper. One is for the approximate trigger position during testing under triangle wave excitation. Another is for high accuracy demand. The current source is tested, its output characteristics and response time are analysed.⑤The dynamic response is studied on the long-term quiescence MR damper according to the testing method and testing system proposed in this paper. The classical response time of MR damper is acquired, and some influence factors for dynamic response are studied, such as long-term quiescence, applied current, and piston velocity.