Dynamic Modeling Method Of Planetary Gearbox Considering Stiffness Excitation And Error Excitation

With the advantages of compact structure,high gear transmission ratio and high loading efficiency,epicyclic gear train is one of the key components of mechanical transmission system.Complex and dynamic operating conditions often trigger excessive vibration in planetary gearing.Therefore,to avoid damage,lower service life and increased maintenance costs caused by excessive vibration,it is necessary to conduct relevant investigations on the vibration response of planetary gearing.A planetary gearing dynamics model,considering various excitation effects,was established to match the dynamic response of the planetary gearing in actual operation,which can provide the necessary evidence for condition monitoring and fault diagnosis of the planetary gearing.The rigid-flexible coupling model has the advantages of both lumped-parameter model and finite element model.Therefore,this paper choose the rigid-flexible coupling model of planetary gearing as the research object.The main research contents and innovation points are as follows,(1)To address the problem that the model evaluation is not efficient in the process of constructing the gear meshing model based on the finite element method to calculate the time-varying meshing stiffness of gear pairs,this paper suggests the gear meshing modeling method based on MPC algorithm to achieve the transition of different mesh densities by coordinating the degrees of freedom of nodes,which effectively reduces the number of nodes and cells of the overall model and improves the efficiency of model evaluation while ensuring the calculation accuracy.It is evidenced that MPC algorithm is accurate and effective by comparing the MPC method with the commonly used meshing transition methods.(2)To address the problem that the existing rigid-flexible coupling modeling of planetary gearing with broken tooth fault of sun wheel does not consider the time-varying meshing stiffness excitation,this paper introduces a rigid-flexible modeling method for planetary gearing that considers both damage error excitation and stiffness excitation.The time-varying meshing stiffness is taken into account in the rigid-flexible coupling model under the sun wheel broken tooth fault.Based on this model,we respectively investigated the effect of the change of stiffness on the dynamic response of the system caused by the normal gear meshing and the broken gear meshing.The study results indicate that the time-varying performance considering both two parts of the stiffness can effectively improve the spectral similarity between the simulated and measured signals.(3)To address the rotational and multiplier frequency difference of spectral peaks between the simulated and measured vibration signals generated by the existing rigidflexible coupling model of planetary gearing,this paper introduces the geometric eccentricity error of the sun wheel into the rigid-flexible coupling model of planetary gearing,and proposes a rigid-flexible coupling modeling method of planetary gearing considering both error excitation and stiffness excitation to analyze the influence of gear error on the dynamic response of the system.The study results suggest that the eccentricity error of the sun wheel is one of the factors causing the spectral peaks of the vibration signal spectrum of the planetary gearing at the rotational and multiplier frequency.In addition,the similarity of the low-frequency components between the simulated and measured signals can be effectively improved by considering the geometric eccentricity error of the gear pairs.