| The locomotive traction gearbox transmission system,as the core component of the locomotive and rolling stock,is used to transform the traction power with high speed and low torque of the traction motor into the traction power with low speed and high torque.As the load-bearing component of the gear transmission system,the gearbox body not only bears the internal excitation from the meshing gear pair,but also is affected by the external excitation caused by factors such as track irregularities.According to statistics,the main form of failure of the gearbox case is fatigue damage,and with the development of locomotives and vehicles in the direction of high speed and heavy load,higher requirements are put forward for the fatigue performance of the gearbox case.Therefore,the fatigue durability analysis of the gearbox is of great significance to improve the operating mileage of rolling stock.This article takes a certain type of locomotive traction gearbox case as the research object,comprehensively considers the internal and external excitation of the traction gearbox case,and analyzes the fatigue life of the case.First,use Abaqus to perform modal analysis on the simplified traction gearbox case and generate the corresponding sub-structure model.After processing,the Fbi flexible body file of the gearbox box body is obtained and imported into Simpack to create the rigid-flexible coupling dynamics model of the whole vehicle including the flexible gearbox box body.Considering the time-varying stiffness excitation,error excitation,meshing impact excitation and other factors of the meshing gear pair,the dynamic simulation of the transmission system is carried out,and the rationality of the gearbox transmission system created above is verified through time domain analysis and frequency domain analysis.The gear tooth meshing force is solved under different load conditions,and the change law of the gear pair meshing stiffness is analyzed.In the post-processing process of Simpack,the displacement time history and stress time history of each node of the gearbox case were obtained based on the dynamic stress recovery,which verified the reliability of the gearbox case strength.Based on the inverse Fourier transform and random number method,the track irregularity power spectrum density function is converted into track irregularity line spectrum space distance domain samples,different track lines are established in Simpack,and the irregularity spectrum is added to the track line.Next,the vehicle dynamics analysis was carried out,and the safety of the locomotive dynamics model created was verified through three standards of non-linear critical speed,derailment coefficient and wheel load reduction rate.A comparative analysis was carried out under three working conditions of without gearbox transmission system,rigid gearbox transmission system and flexible gearbox transmission system,and the influence law of gearbox transmission system on the vibration characteristics of locomotives and vehicles was obtained.Based on the box dynamic stress time series obtained from the above-mentioned vehicle rigid-flexible coupling dynamic analysis,the fatigue life of each node of the gearbox is calculated by using the fatigue cumulative damage theory.The fatigue damage analysis method of the gearbox case obtained from the above research provides a theoretical basis for the structural optimization and lightweight of the traction gearbox case in the future. |
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