| As a typical passive vibration absorption device,the nonlinear energy sink has good vibration suppression performance under the action of harmonic excitation,plus its advantages of small additional mass,good robustness and frequency bandwidth of vibration suppression.Therefore,it has broad application prospects in the aerospace field.However,with the development of aerospace technology,the complex and changeable aerospace environment and rich dynamic loads have become the main obstacles restricting the development of spacecraft vibration isolation and vibration absorption technology.Therefore,this paper focuses on the application of nonlinear energy sinks in the whole-space vibration isolation technology and the integration of energy harvesting,and further studies its complex dynamic behavior under the combined action of Gaussian white noise and harmonic excitation Two new evaluation indicators: force transmissibility transfer probability density and energy absorption percentage of main oscillator transfer probability density,are proposed to evaluate its vibration suppression performance.For the first time,a non-linear energy sink coupled giant magnetostrictive material integrated system was applied to a random dynamic environment,and its vibration suppression mechanism and energy harvesting efficiency were studied in depth.The specific research content is as follows:The first chapter clarifies the background and significance of the research.The research status of the whole-space vibration isolation technology and the nonlinear energy sink are introduced from two aspects at home and abroad.Finally,according to the shortcomings in the current research work,the research content and innovations of this article are expounded.The second chapter studies the vibration suppression of the linear structure damping system with nonlinear energy sink under the excitation of Gaussian white noise.First,the model is established,in which the linear main structure part is simplified to a single degree of freedom system.Then,the generalized harmonic function method is used to derive the FPK equation and the fourth-order central difference method and the super-relaxation iteration method are used to obtain the numerical solution of the steady FPK equation,that is,the displacement and velocity transfer probability density of the main oscillator and the nonlinear energy sink.The Monte Carlo method is simulated to verify the accuracy of the numerical solution.Finally,the effects of nonlinear stiffness,nonlinear energy sink damping,mass ratio,and external noise intensity on the system's vibration suppression performance are studied respectively,and the effects of these parameters on random bifurcation phenomena are focused on.The third chapter studies the vibration suppression of the linear structure damping system with nonlinear energy sink under the combined action of Gaussian white noise and harmonic excitation.First,the model in Chapter 2 is applied to the dynamic environment under the combined action of Gaussian white noise and harmonic excitation to investigate the universality of the nonlinear energy sink in a complex dynamic environment.Then,according to the dynamic control equation of the model,the FPK equation is derived using the generalized harmonic function method and the numerical solution of the steady FPK equation is obtained by the modified path integration method.For the first time,the displacement and velocity transfer probability density of the main oscillator and nonlinear energy sink,the force transmissibility transfer probability density,and the energy absorption percentage of main oscillator transfer probability density are used as evaluation indicators to comprehensively evaluate the vibration suppression performance of the system.Finally,the effects of external noise intensity,nonlinear stiffness,and nonlinear energy sink damping ratio on the evaluation index are investigated.Chapter 4 studies the vibration suppression and energy harvesting of an integrated system with nonlinear energy sink coupled with giant magnetostrictive materials under random excitation of Gaussian white noise.First,the J-A model is used to derive the energy conversion relationship of the one-dimensional giant magnetostrictive material energy harvester.Then,an integrated model of nonlinear energy sink coupled giant magnetostrictive materials under Gaussian white noise excitation is established,and the mechanical-electric-magnetic coupling governing equations are derived.Secondly,the FPK equation is derived using the generalized harmonic function and the numerical solution of the steady FPK equation is obtained using the fourth-order central difference method and the super-relaxation iteration method.The displacement and amplitude transfer probability densities of the main oscillator under the same parameters and external excitation are compared for the integrated system,the linear system with nonlinear energy sink,and the single-degree-of-freedom linear system.Finally,the effects of noise intensity,damping of linear structure,damping of nonlinear energy sink and nonlinear stiffness on the mean squared value of output voltage and output power are studied.Chapter 5 performs finite element simulation on the whole-space system with nonlinear energy sink.First of all,using ABAQUS finite element software to establish a whole-space reduction ratio model with nonlinear energy sink and a whole-space reduction ratio model without nonlinear energy sink,in which the mass installed on the top of the cone,viscous damping and guide The thin wire drawn by the rod simulates a nonlinear energy sink.Then the acceleration basic excitation of the same Gaussian white noise intensity is applied to both.Finally,the RMS displacements of the satellite and the nonlinear energy sink in the former second-order longitudinal vibration mode of the two are compared,the results verifies the nonlinear energy sink can well suppress the longitudinal vibration of the satelliteChapter 6 summarizes the full study and lists the main research conclusions and prospects for future work. |
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