Based on the contact nonlinear analysis technology,the fatigue problem of the coal hopper car body weld is studied by using the nominal stress method in the AAR standard and the structural stress method in the ASME standard.Firstly,the strength analysis model of the heavy-duty body of hopper car is established.In the model,the solid element with modified D-P constitutive model is used to simulate the granular coal,and the contact element is used to simulate the interaction between the granular coal and the car body structure.The static strength test results of the car body under the main load verify the simulation analysis results of the car body,and the maximum stress error is less than 15％.Then,the nominal stress method is used to analyze the fatigue life of the car body weld under standard and measured load spectrum.The results show that the weld life of the end wall and end funnel plate is the shortest,which is 2.72×106 km.The weld life based on the standard longitudinal load spectrum is less than that based on the measured spectrum,which shows that the standard longitudinal load spectrum is relatively bad.Finally,the structural stress method is used to analyze the stress and life of the car body weld under the standard 100t hopper car load spectrum and measured longi-tudinal load spectrum.The results show that the fatigue life of the weld based on the structural stress method is shorter than that based on the nominal stress method.The main reason is that the fatigue performance parame-ters of the structural stress method are suitable for various joint forms,and the influence of in-plane shear structural stress is considered when analyzing the bearing complex weld.Therefore,the structural stress meth-od is recommended for fatigue life analysis of the welds from the plate base and the chassis area of the car body with complex joint geometry and stress state.
hopper car bodymodified D-P modelload spectrumstructural stressweld fatigue
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