Research On Dynamic Characteristics Of Planetary Gear Transmission With Crack

Gear transmission is widely used in the equipment manufacturing industry due to its advantages such as high efficiency,long service life,large power and High accuracy.But under long term fatigue load,the gear is damaged easily.And the tooth root crack,as one of the most common failure forms of gears,will break the gear system;even break all the drive system.Therefore,acquaintance with the form reason of crack and mastering working dynamic characteristics of cracked gear system are of great theoretical significance and potential engineering value for fault monitoring,identifying and diagnosing.This thesis focuses on the dynamic characteristics based on the time-varying meshing stiffness with tooth root crack,and takes the dynamic characteristics of single planetary gear as the object of study,establishes the dynamic model of 2K-H planetary gear.Then the effects of crack and crack parameters on the dynamic characteristics of planetary gear system are investigated.And the main works are as follows:1?Based on the gear meshing stiffness,deduce the calculation equations with tooth root crack using potential energy method,which including Hertzian contact stiffness,fillet foundation stiffness,shear stiffness,bending stiffness and axial compressive stiffness.And the influence of various crack parameters and friction on the time-varying meshing stiffness of gears with cracks is discussed.The results show that the existence of cracks will reduce the time-varying meshing stiffness.And crack length has the greatest influence on the time-varying mesh stiffness.2?Taking the dynamic characteristics of single planetary gear as the object of study,using lumped mass methodthe,the dynamic model of the 2K-H planetary system with 21 degrees of freedom is established,considering time-varying meshing stiffness and damping factors.Variable step size Runge-Kutta method is adopted using Matlab to solve the dynamic response of the system.3?Based on the dynamic model,considering the effect of crack on the meshing stiffness,Analysis the dynamic characteristics of planetary gear system with crack.Finding that the crack has little influence on the inherent characteristics and modes,but the time domain signal of the vibration response will be impacted obviously,and the frequency band will appear in the frequency domain.The appearance of the crack will reduce the dynamic meshing force,which provides an important theoretical basis for the diagnosis and identification of the crack.