Torsional Vibration Suppression Of Long-shaft-rotor-system Based On Multi-stable Nonlinear Energy Sink

Long-shaft-rotor-system will inevitably produce torsional vibration during operation,which will affect the normal operation of rotating machinery.In order to ensure the safety of the equipment,it is necessary to suppress the torsional vibration of the long-shaftrotor-system.As a common vibration suppression structure,torsional vibration absorber can be divided into passive and active types:passive vibration absorbers are simple in structure,but the effective vibration absorption frequency band is narrow;active vibration absorbers have a bandwidth of vibration suppression frequency,but the structure is complex and the reliability is low.The proposal of the nonlinear energy sink(NES)solves the obvious shortcomings of the two types of traditional vibration absorbers,but still has the problem of a narrow energy threshold,which limits its wide range of engineering applications.Based on the above background and problems,in order to expand the energy threshold of NES,a multi-stable nonlinear energy sink(MNES)structure is designed and applied to the rotor system for torsional vibration suppression analysis.The main research contents of this thesis are as follows:(1)The establishment of the rotor-MNES system model.MNES is designed for the torsional vibration suppression of the long-shaft-rotor-system.The principle of positive and negative stiffness of the MNES structure and the overall stiffness characteristics are analyzed,and then the dynamic model of the rotor-MNES system is established.(2)Analysis of the effect of MNES torsional vibration suppression.According to the established dynamic model of the rotor-MNES,simulation analysis of the effect of MNES on the torsional vibration of the rotor system under transient excitation and steady-state excitation conditions is analyzed.(3)Analysis and optimization of the parameters of MNES.The torsional stiffness,moment of inertia and other parameters of the MNES were changed,and the influence of each parameter on the vibration suppression effect of the MNES was analyzed;the parameters with greater influence were selected and the genetic algorithm was used to optimize the parameters of the torsional vibration suppression of the rotor system by the MNES,and the MNES obtained the best vibration suppression parameters.The MNES is compared with the linear vibration absorber,and the broadband vibration suppression capability of the MNES is verified.(4)Test verification of MNES torsional vibration suppression.A test bed for the multi-disk rotor system and the MNES coupling system was built;the vibration reduction of the rotor system when the MNES with different parameters was added and the comparison with the torsional vibration suppression effect of the linear vibration absorber were verified through experiments;The broadband vibration suppression capability of MNES is verified.The research shows that the designed MNES can effectively reduce the torsional vibration of the long-shaft rotor.The results of the study can provide a reference for the vibration suppression of the long-shaft rotor system in actual engineering.