Research On Rigid-flexible Coupling Dynamics Of Flexible Cone-probe Docking Mechanism

In this paper,a new kind of flexible cone composed of the thin-walled plates based on space probe-cone docking mechanism for medium and small-sized spacecraft is presented.The rigid-flexible coupling dynamic model of docking impact dynamics,which takes into account the additional stiffness terms,is derived based on large deformation contact theory.Furthermore,the correctness of the model is verified by experiment.A set of equations are established to predict the large deformation contact problem of a thin plate contacting an elastic sphere under several common boundary constraint based on the basic theory of elastic mechanics,the basic equation of circular thin plate with large deformation and the kind of reciprocal theory.On this basis,comparison of the results with the Hertz theory is presented.The obtained results show that the relative penetration derived in the paper is less than that given by the Hertz theory in the case of identical force,while the radius of contact area does not change significantly,which indicates that the Hertz theory is not applicable to the elastic sphere in contact with the circular thin plate with large deformation.For the space flexible probe-cone docking mechanism,the theoretical model of docking impact dynamics,which takes into account the additional stiffness terms,is built successfully based on Lagrange Analytical Mechanics theory and large deformation contact theory.Finite element method is employed for discretization of the thin-walled plate.In addition,the influence of the initial velocity of the active satellite,the thin-walled plate thickness,the thin-walled plate Young’s modulus,the docking probe radius and the initial contact point are analyzed in detail.The obtained results show that traditional dynamic model without considering the additional stiffness terms will get unstable results.The method proposed in this paper can correctly predict the dynamic behavior of the system.For the space flexible probe-cone docking mechanism,Kane method and large deformation contact theory are used to obtain the governing equations.The Assumed Modes Method is considered in order to discretize the thin-walled plate.These equations are then coded into a computer program and solved using fourth-order Runge-Kutta methods.The obtained results show that Kane method makes the modeling more simple as compared with Lagrange method by saving large numbers of integral operation.An impact experimental system is designed in order to prove the correctness of the large deformation contact theory proposed in this paper.The piezoelectric pressure transducer and the force measuring instrument are applied to control the output of the screw force.The surface displacements of the thin-walled plate are measured precisely by the three coordinate measuring machine.Results of the theoretical model show a good agreement with the experimental results.In order to prove the correctness of theoretical model,a new impact testing system is designed to investigate the impact phenomenon of this docking mechanism.The active and passive satellites float on the air-bearing platform in order to simulate the space docking operation.The air-lubricated linear guide that is able to make the active satellite exactly move in a setting velocity supplies the active satellite the driving force.In the experiment,the acceleration time history can be measured by the accelerometer,and the time history of impact force can be calculated indirectly.Results of the theoretical model are found to be in good agreement with the experimental results.