| Nonlinear energy sink,as one of passive vibration control devices,can achieve high energy dissipation rate in a unidirectional and irreversible way.Because of its light weight,wide damping frequency and other characteristics,NES has a broad application prospect.In this paper,different structures of nonlinear energy traps and nonlinear and asymmetric vibration subsystems with nonlinear energy traps are studied.particle swarm optimization(PSO)is applied to optimize the nonlinear energy trap with the structural parameters of nonlinear and asymmetric vibration subsystems or the transmitted energy difference.In this paper,particle algorithm is used to obtain the optimal vibration absorption efficiency of nonlinear energy trap,which provides theoretical basis and data reference for active or semi-active control of NES.The main research contents are as follows:Particle swarm optimization(PSO)algorithm is used to study the variation of optimal parameters of NES with impact load.The optimal vibration absorption efficiency and optimal parameters of NES are compared and analyzed under the conditions of only changing stiffness and simultaneously changing damping and stiffness.The results show that the vibration absorption efficiency of the optimized NES with two degrees of freedom is slightly better than that of the NES with one degree of freedom.With the increase of impact load,the optimal stiffness of the two NES gradually decreases and the optimal damping gradually increases.Considering passive devices,the vibration absorption efficiency of NES with two degrees of freedom is obviously better than that of NES with one degree of freedom.If control is added to keep NES in the optimal parameters all the time,the efficiency advantage of NES with two degrees of freedom is very small,and there are many control parameters.The variation law of optimal parameters of parallel pure cubic stiffness and parallel non-smooth NES is studied,and the vibration absorption efficiency of them is compared and analyzed.The dynamic equations of the system connecting parallel NES with pure cubic stiffness and parallel non-smooth NES are derived by using Hamilton principle,and the optimal vibration absorption efficiency and optimal parameters of the two NES are obtained by using particle swarm optimization(PSO)and compared and analyzed.The results show that NES with pure cubic stiffness before optimization shows slightly higher vibration absorption efficiency under moderate load,but with the increase of impact load,the vibration absorption efficiency of non-smooth NES is better than that of pure cubic NES.Furthermore,the variation law of the optimal vibration absorption efficiency of the two NES with load shows that the optimized non-smooth NES has better vibration absorption efficiency under large impact load.The non-reciprocity of energy transfer in a nonlinear asymmetric vibration subsystem and its control method are studied.Firstly,the slow-changing equation of the system is derived by the complex variable averaging method,and then the semi-analytical solution of the system is obtained by the least square method.The correctness of the calculation process is verified by comparing the semi-analytical solution with the numerical solution obtained by Runge Kutta method.The change of non-reciprocity under different excitation amplitudes is analyzed.The results show that under large excitation amplitude,no matter whether the left vibrator or the right vibrator is excited,chaos can appear near the resonance frequency.In addition,the difference between the energy transfer to the left and the energy transfer to the right is used to further analyze the non-reciprocity of energy transfer in the oscillator subsystem.Finally,the parameters of the structure are optimized by particle swarm optimization to maximize the energy difference between the left and right linear oscillators,and the variation law of the energy difference is studied. |
PDF Full Text Request