Theoretical And Experimental Research On Stiffness Optimization Of Whole-spacecraft Vibration Absorption Based On Nonlinear Energy Sink

Before entering a predetermined orbit,the satellite needs to withstand a series of harsh vibration environments,and these environmental loads can be directly transmitted from interface between satellite and rocket to the satellite,which has a great impact on the satellite's precision equipment.This paper mainly studies the introduction of nonlinear energy sink in the equivalent dynamic model of the whole-spacecraft system to control the vibration of shock and harmonic loading conditions,and optimizes the stiffness of the nonlinear energy sink according to the target energy transfer relationship.The optimal cubic stiffness range is obtained,and then a nonlinear energy sink with cubic stiffness is designed and processed.Finally,the response of the nonlinear energy sink before and after the addition of the nonlinear energy sink is used to compare and analyze the vibration absorption effect of the device to verify the correctness of the designed stiffness range.The specific content includes:Firstly,use the 3D software to establish the whole-spacecraft system model,and then import it into the Ansys finite element simulation software,set the corresponding external excitation and other conditions to simulate the specific working conditions during the launch process,and then conduct modal analysis and harmonious response analysis in turn,through the analysis results of the software we obtain the range of each order mode of the whole-spacecraft system and the response status during the launch process,and then establish a two-degree-of-freedom equivalent model with the same resonance frequency and amplitude according to the frequency response curve obtained by the harmonic response analysis.Secondly,a nonlinear energy sink is introduced into the whole-spacecraft equivalent model to study the response under shock conditions and harmonic conditions.Solve the analytical relationship of the equation by the complex variable averaging method,then use the target energy transfer conditions and the analytical relationship between the parameters to optimize the stiffness of the nonlinear energy sink,derive the optimal cubic stiffness formula,and study the multi-solution to give the upper limit of the optimal cubic stiffness,and finally get an optimal cubic stiffness range.Thirdly,the combination of different springs is used to theoretically construct a spring with pure cubic stiffness;the structural design and processing of the nonlinear energy sink device,and the construction of a spring tension and compression experimental platform;The nonlinear energy sink device separately conducts tensile and compression experiments,and compares the experimental results with the expected theory to verify the correctness of the cubic spring construction theory.Finally,the sinusoidal excitation test was performed on the whole-spacecraft system,and the experimental results were compared with the finite element simulation results.Then the nonlinear energy sink with different stiffness was added to the whole-spacecraft system to perform the sinusoidal excitation test.The test results are compared with the results without the nonlinear energy sink to study the vibration absorption effect of the nonlinear energy sink,and to verify the correctness of the designed stiffness range.