Dynamic Characteristics Analysis Of Two Stage Gear Rotor Transmission System With Multi Source Excitation Coupling

Multi stage gear rotor drive system is an indispensable part of power mechanical equipment.Geometric eccentricity of gears,the initial bending of shaft and the backlash have a very important influence on the performance of the whole system.As the increasing needs of society for the performance of rotating machinery,it is of great guiding significance and engineering application value for the design and processing of multi-stage gear rotor drive system to grasp the regular pattern of multi-source excitation factors and diverse conditions on the transient response of multi-stage gear rotor drive system.In this paper,a two-stage gear rotor transmission system composed of involute spur gears is studied.The time-varying meshing stiffness and the two-stage assembly phase relationship of the gears are taken into account,and the influence of the geometric eccentricity of the gears,the initial bending of the shaft section and the backlash on the system is also considered,The dynamic model of a two-stage gear rotor transmission system with multi-source excitation coupling is established by using the finite element method.The Newmark integral method is used to solve the problem.The natural characteristics and mode coupling of the system are studied through modal analysis.The effects of various excitation factors on the dynamic performance of the two-stage gear rotor transmission system are compared and explored.Finally,the vibration characteristics experiment is carried out to verify the relevant conclusions.The main conclusions are as follows:1.The two-stage gear-rotor transmission system is concerned as the object.The algorithms of engaging frequency and eigenfrequency are listed.The inherent characteristics of the system are analysed,and the influence of speed and two-stage assembly phase relationship on the natural characteristics of the system is discussed.The results turn out that: in the two-stage transmission system,there are not only the bending and torsion coupling of the same stage transmission,but also the bending and torsion coupling,bending and bending coupling,torsion and torsion coupling among different stages.The susceptibility of distinct natural frequencies to speed is various,and the higher frequencies are more susceptible to the velocity.When the assembly phase angle is different,different natural frequencies of the system can also change.2.The dynamic properties of the two-stage gear rotor system with only considering the eccentricity of the gear are discussed.The influence of the inflexibility of the support,the rigidity of the shaft and the assembly phase angle on the dynamic performance of the system are investigated.The research shows that the eccentricity of the gear can bring about the reduction of the smoothness in the running process.As the increase of eccentricity,the fluctuation magnitude of the two-stage dynamic engagement force is proportional to the eccentricity,and the peak vibration of the gyrofrequency increases and gradually dominates the resonances,the modulation effect is becoming more and more notable.As the increase of supporting inflexibility,the constraint at the bearing is further enhanced.Under the same speed and load,the system will produce stronger vibration.When the drive shaft is a nonflexible shaft,it will produce more severe vibration than the flexible shaft,and the flexible transmission shaft can absorb and suppress the vibration.The assembly phase angle of the system has a certain impact on the dynamic properties of the system.As the raise of the angle,the peak of the first stage dynamic engagement force first declines and then rises with the adding of the assembly phase angle.The peak of the second stage dynamic engagement force climb up and then decline,and then increases,the bearings live load of the system also raises little by little.3.The impact of initial bending and backlash on the dynamic properties of the twostage gear rotor system are studied.The results reveal that: the initial bending of the shaft has a great effect on the stationarity of the system;as the initial curvature raises,the fluctuation of the engagement force becomes more striking,the crest value caused by the through frequency of the bearing is gradually gathering,and the modulation is more notable.As the increase of the revolution velocity,the larger the backlash is,the greater the impact on the engagement performance of the system is.4.Taking into account the geometric eccentricity of the gears,initial bending of shaft and backlash,the kinetic model of two-stage gear rotor system with multi excitation coupling is created,and the dynamic properties under multi-source excitation is analyzed.The results turn out that: with the increase of load torque,the fluctuation amplitude of the vibration response of the system will heighten,the first level meshing force presents a serrated periodic fluctuation,the second level meshing force shows a beat vibration phenomenon,and as the load increases,the beat vibration phenomenon gradually weakens.As the adding of the revolution velocity,the engagement force and bearing dynamic load increase apparently.When the damping of the whole system increases,the peak value and amplitude of the two-stage engagement force response of the system gradually decrease,which suppresses the fluctuation of the bonding force to a certain extent.