| The application of flexible rod to space probe-cone docking impact process belongs to flexible multi-body dynamics problem. In addition, it includes study of impact transient dynamics. Therefore, it is a great difficult problem. From now on, the study of flexible probe impact problem is still in the primary stage, the thorough research work has a greater challenge.The flexible multi-body dynamics system containing oblique collision is used as the research object. Theoretical modeling, simulation calculation and ground based experiment is used jointly to solve this problem. The complicated nonlinear dynamics in space flexible docking process is revealed comprehensively by theoretical modeling of flexible probe docking impact process, simulation analyzing of frequency characteristic and vibration characteristic and by ground based experiment of space probe-cone docking process. The main research content and contributions of this dissertation are as following:(1) The theoretical model of docking impact dynamics based on flexible beam is built according to the Lagrange Analytical Mechanics theory. The contact problem is solved by using Hertz point-surface contact model. Assumed Modes Method is introduced to describe the deformation of flexible beam. Runge-Kutta numerical method is used to solve this theoretical model. Results of the theoretical model give a reasonable description of the first impact situation.(2) The simplified probe-cone docking impact model is built using finite element method. By time-frequency domain analyzing of simulation results, the relationship of flexible impact frequency characteristic and vibration modals is discovered. By comparative analyzing of finite element method and theoretical model results, the correctness of theoretical model in describing the first impact situation is verified. By changing the stiffness of flexible rod, the influence of stiffness to impact process is discussed.(3) The ground based impact experiment system of probe-cone docking mechanism is designed. The whole scheme of the system, which includes the composition of the experiment system, experiment process, experimental sample and design of related devices, is given. The method of choosing accelerometer sensor is introduced in detail. The measuring method of docking impact force using accelerometer and data processing method is discussed. Results of experimentation show the correctness of theoretical model in one hand, and show the feasibility of experimental method in another hand.(4) The structure optimization work is developed based on flexible docking impact theoretical model. Genetic Algorithm is used as the optimization algorithm. The collision buffer performance is compared between ordinary straight docking probe and optimized probe based on finite element method. The results of comparison show the validity of optimization result. Two types of large deformation docking probe are designed through reasonable bold design. Their buffering characteristic is analyzed based on Pro/E and MSC.Patran/Dytran joint modeling. Some valuable conclusions are obtained by buffer characteristic comparing between large deformation probe and ordinary straight probe. Under the guidance of these conclusions, a composite structure docking probe with spring and soft-rod is designed. The performance advantage of composite structure probe is verified by ground impact experiment. |
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