Research On Dynamics Of Nonlinear Energy Sink Under Stochastic Excitation

For space vehicles,working conditions of sensitive instruments and load in spacecraft are directly or indirectly affected by the complex and changeable dynamic environment.Therefore,aircraft and components of vibration suppression has been one of the key issues in the field of aerospace engineering.In recent years,due to high efficiency and robustness of vibration suppression under certain conditions,nonlinear absorber has shown great promise in the field of engineering application and received extensive attention by researchers gradually.From the perspective of damping parameters and nonlinear forms of nonlinear energy sink,the conditions of targeted energy transfer are investigated,and the mechanism of targeted energy transfer under the stochastic excitation is discussed.The main contents are summarized in the following aspects:Aiming at the problem of energy transfer in the system of structural damping,the relationship between energy transfer and dissipation and structural parameters of the system is derived based on the complex variable average method.The effect of system damping on energy transfer and dissipation is discussed from the point of view of energy flow in the system.The necessary conditions to satisfy the damping of the coupled NES system triggered targeted energy transfer are presented.A nonlinear stiffness coefficient design method of energy sink is proposed based on those to ensure the best efficiency of vibration suppression.Several numerical simulation examples are completed to verify the validity of method.In order to improve the practicability of the energy sink in the field of engineering,the energy transfer of the bilinear hysteretic nonlinear energy sink with sinusoidal excitation is investigated based on the phase trajectory method.A nonlinear analysis method based on Hilbert transform is proposed,in which the system parameters are unknown,and the nonlinear characteristics of the system are analyzed by the vibration response.Considering that the external sinusoidal excitation frequency is hard to meet the requirements of the hysteresis nonlinear energy sink,the vibration suppression characteristics of the energy sink in the non-resonant region are studied based on the improved incremental harmonic balance method.Considering that the energy transfer and dissipation of the system subjected to narrow band random excitation,and based on the stochastic averaging method,the system is written in a standard form of Ito equation.The solution of the probability density related to the structural parameters of the system is obtained by the path integral method.Combining with energy sink conclusion under determine excitation,response of system and trigger conditions of targeted energy transfer are analyzed when the narrow-band excitation amplitude and disturbance intensity and quality than the same order of magnitude.By comparison with the numerical analysis of the energy dissipation rate of the optimal linear damper,the effect of energy sink under a narrow band random excitation on the vibration suppression is evaluated.For the problem of vibration suppression of a single degree of freedom system with a nonlinear attachment under a harmonic excitation and white noise,frequency response function only by sinusoidal excitation system is solved by complex variable average method and two points tracing algorithm,and the mechanism of targeted energy sink of energy sink under the white noise is predicted.Based on four order stochastic differential Runge-Kutta method,evolution of Poincare mapping with different strength of white noise is analyzed and the characteristics of response of the system subjected to white noise is discussed.By means of wavelet transform,the possibility of targeted energy transfer in the system with a energy sink is revealed under the condition of small noise intensity.Based on the meshless method of radial basis function,the probability density evolution law of the system is studied and analyzed,and the mechanism of vibration suppression of the energy sink under stochastic disturbance is expounded.