Dynamic Analysis And Vibration Control Of A Flexible Four Linkage Mechanism

With recent development of industry, considerable attention has been paid to the investigation of the dynamic analysis and active vibration control of flexible mechanisms in order to achieve high-speed and lightweight machines with accurate performances. Inhibiting the flexible vibration of flexible lightweight connecting rod mechanism is a key point while designing products in package-mechanism, aerospace and the military field. The FEM is introduced to model the governing equations of the flexible four-linkage mechanism which is one typical part of package-mechanism and used widely in other machines. Then, several numerical methods are employed to solve the deferential equation. The active vibration control is studied in this dissertation.Dynamic modeling of four-linkage mechanism containing the flexible connecting rod using FEM, the coupling effects of rigid motion and flexible vibrations are considered. Calculating the strain energy include the shear deformation, the influence of horizontal deformation to tension and compression strain energy. Therefore, the model describes the dynamic behavior of flexible linkage mechanism systems operating at high speeds more accurately.In this study, numerical integration method is utilized to solve the dynamic system which are time-varying coupling and can't be solved by real mode technique. Wilson-θtechnique of direct differential method is used to compute the response of dynamic system. Besides, QDA and KES approaches are applied to solve the simplified model, At last, software ADAMS is used for modeling and analyzing the flexible four-linkage mechanism, and the result shows that there are some elastic vibration in connecting rod, thus affect the stability of output link more or less. Through comparing with the responses of flexible four bar linkage solved by above mentioned three methods, it can be seen that, the numerical result of QDA is more closely to ADAMS result than KES technique.Experimental investigations are carried out to the flexible four-linkage mechanism based on experiment equipment whose connecting rod was remanufactured. The result of the experiment proved the modeling method which is introduced in chapter two and the response result in chapter three are correct.An active vibration controller is designed by using sliding mode control theory. Through changing the control input function, the sliding mode controller not only satisfies the control requirement but also eliminates the dynamic deflections of output link. Simulation result proves the validity of the method.