Abstract
The gearbox shell is a key component of class A of high-speed trains. In engineering applications, the fatigue life prediction of the gearbox shell is a critical issue to be addressed. It is not feasible to obtain fatigue life results for the gearbox shell experimentally because of its long design life, lack of actual failure data, complex structure, high test cost, and material dispersion. Therefore, the cross-scale method was introduced to accurately predict the fatigue life of the gearbox shell. In this study, the entire gearbox shell is divided into two scales of “material structure.” Firstly, the S-N curve is plotted within the material layer, based on the data from the rotating bending fatigue test. Secondly, the finite element model of the gearbox shell is established within the structural layer via the simulation platform. The characteristics and random vibration of the established model are analyzed and presented. Additionally, the first ten-order frequency of modal analysis and power spectral density responses of the gearbox are obtained. The fatigue life of the gearbox shell and the safe running distance of the train are calculated by using the three-interval method and the linear cumulative damage rule, respectively, by combining the fatigue analysis from the material layer with the simulation analysis from the structure layer. Finally, to illustrate the application of the proposed method, a group of small-scale test examples is provided. The proposed method can be used in fatigue life prediction more effectively than the single finite element simulation method.
Highlights
Fatigue damage failure is caused by the reciprocating oscillation of the gearbox when the train is running, while tensile damage failure is due to its static load and external impact on the gearbox
Its characteristics include long design life, lack of actual failure data, a complex structure, high test cost, inability to conduct an independent test for a single shell, and material dispersion [3]
Because the high-speed train gearbox shell has the characteristics of long design life, lack of actual failure data, complex structure, high test cost, disabled to conduct an independent test for a single shell, material dispersion, and so on, it is not suitable to obtain fatigue test data via the traditional test method and the finite element simulation technology
Summary
As a key component of class A of high-speed trains, the gearbox has an important influence on the safe operation of high-speed trains [1]. e gearbox is located at the bottom of the train and is suspended on the moving shaft. The S-N curve model of the material layer is established by fitting 11 sets of experimental data under different stress amplitudes. To determine the S-N curve of the gearbox shell material of a high-speed train [14], standard samples must be cast according to the material composition of the gearbox shell and a rotating bending fatigue test must be conducted. In the rotating bending fatigue test, the samples used are high-strength aluminum alloy A356, which is the same material as that of the gearbox shell of a high-speed train. The number of cycles under other stress amplitude conditions could be calculated and converted into logarithmic form to obtain 11 sets of processed experimental data. E logarithmic relationship between the number of fatigue cycles of the gearbox shell material and the stress amplitude is expressed as equation (6): lgN 17.76904 − 5.58984lgS.
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