Research On Vibration Suppression Mechanism Of Multi-stable Nonlinear Energy Sink

Mechanical equipment is often accompanied by vibration during the operation,vibration problems are inevitable when the machine tool is machining parts or the rotor system is rotating at high speed.Especially when the mechanical equipment is over the resonance frequency,the amplitude will increase sharply,and the production equipment will often cause fatigue damage,which greatly reduces the normal service life of the equipment.Therefore,in order to ensure the safe and stable operation of mechanical equipment,it is important to reduce or suppress the vibration of the mechanical system during resonance.The active vibration absorber or the passive vibration absorber is a common vibration damping structure,and there are defects such as limited vibration suppression frequency band and difficulty in adjustment;At the same time,NES and BNES have high requirements on the initial energy threshold when suppressing the transient vibration of the main system.The above problems greatly affect the use range of such damping structures.In order to solve the above problems,this paper proposes a new type of multi-stable nonlinear energy sink and applies it to the vibration suppression research of cantilever beam system.The main contents of the thesis are as follows:(1)A kind of BNES’s structure is constructed based on a large distance permanent magnet mechanism and a leaf spring,And the cantilever beam system is used as the object of vibration suppression.From the two aspects of the transient and steady-state vibration suppression of the main system,the effectiveness of the BNES for vibration suppression is explored through simulation.And the shortcomings of BNES in vibration suppression are put forward.(2)In view of the shortcomings of BNES in suppressing the vibration of the main system,a new MNES structure consisting of a piecewise linear beam and a large-pitch permanent magnet mechanism is proposed based on the BNES structure,at the same time,the stiffness characteristics,nonlinear force,and steady-state equilibrium position of the MNES are described in detail.(3)This paper also applies MNES to the vibration reduction study of the cantilever beam system.The dynamic equations of the cantilever beam system-MNES coupling system are listed by the lumped mass method,and the effectiveness of MNES on the transient and harmonic vibration suppression of the cantilever beam system is investigated by simulation based on the numerical solution algorithm of Longmen Kutta.(4)Under the same free vibration suppression condition of the cantilever beam system,the vibration absorption effects of BNES and MNES are simulated and compared,and the related parameters such as mass and damping which affects the MNES damping effect are simulated.(5)Based on the above simulation analysis,the cantilever beam system-MNES test rig was built and the simulation results of MNES were compared and verified.