In order to explore the accuracy difference between the equivalent structural stress method and the nominal stress method on the welding fatigue characteristics of the cab

a heavy-duty truck's fully floating air spring cab was taken as the research object

and road load spectrum data of the test site was collected

a rigid-flexible coupling virtual platform model was built and verified. The dynamic fatigue simulation load spectrum data of the cab interface point is solved with the virtual iteration method. The equivalent structural stress method and nominal stress method are used to simulate and analyze the fatigue of seam weld and spot weld of the cab. The results show that the equivalent structural stress method is more conservative than the nominal stress method

and the accuracy of the equivalent structural stress method is higher. The maximum relative error with the bench test result is 33.5%. The equivalent structural stress method is insensitive to the grid. The equivalent structural stress method has the characteristics of identifying the stress concentration effect at the welding position. Finally

the structure and welding process of the dangerous parts of the cab are improved. The fatigue life of cab seam weld and spot weld are increased by 6 times and 3.2 times The effectiveness of the improved scheme was verified by bench test.