| Space cable net-frame structures have the advantages of light weight,easy folding,large shrinkage ratio.They are widely used in satellite communications,deep space exploration and other fields.After this type of structures are deployed and locked in orbit,they will be in a complex and changeable space environment for a long time.At the same time,they may be affected by the attitude adjustment of spacecraft body and the impact of space junk debris.It is prone to continuous violent vibration,which seriously affects its on-orbit performance.Therefore,this paper studies dynamic analysis and vibration control of space cable net-frame structures from the following three aspects.(1)The dynamic spectral element model of space cable net-frame structure is established.Based on the spectral method and the virtual work principle,the spectral element equations of space cable and beam elements are established.The spectral element model of space cable net-frame structure is established through the element group set,and the loop truss antenna structure is used as an example to verify correctness of the space cable net-frame structure dynamic spectral element model.The response histories in time domain of the cable internal node and the cable-beam coupling node in each direction are analyzed through FFT opposite transformation.The results show that the vibration amplitude of cable internal node is much larger than that of cable-beam coupling node.The cable internal node and the cable-beam coupling node vibrate in all directions.When studying their vibration control,the vibration energy in each direction of nodes must be considered comprehensively.(2)The band gap optimization method of space cable net-frame structure is studied.Firstly,the equivalent dynamic spectral element model of super-element structure is established for the periodic space cable net-frame structure,and a numerical example is given to verify it.The super-element structure is expanded into a periodic space cable net-frame structure along the axial direction.Through the analysis of influence factors of space cable net-frame structure band gap,the sensitive structural parameters affecting the band gap are revealed.The structural parameters are taken as design variables.The ratio between the lower limit frequency of the band gap and the band gap width is used as the objective function to establish a band gap optimization model.The results show that optimizing structural parameters can effectively adjust the position of the structural band gap,that is,optimizing structural parameters can significantly improve the passive vibration control effect of space cable net-frame structure itself.(3)The piezoelectric actuation vibration control of space cable net-frame structure is studied.Firstly,the power flow model of space cable net-frame structure is established and the dynamic spectral element model of piezoelectric actuator is deduced.By introducing the frequency domain PD feedback control law,The weighted sum of power flow of total nodes is used as the energy index and the optimization model of piezoelectric actuator position and the optimization model of gain coefficient are established.Taking the overall structure as the object,the piezoelectric actuation vibration control effect is verified.The results show that when the single actuator is configured,the attenuation amplitude of vibration can reach 91.3% within 5s and when the multiple actuators are configured,the attenuation amplitude of vibration can reach 94% within 2s.The position of the actuators should be close to the basic excitation source to effectively reduce vibration and we can improve the vibration control effect of structure through optimizing the feedback gain coefficients. |
PDF Full Text Request