An improved Goodman-Smith fatigue limit diagram for railway vehicle base metals and welded structures.

[Display omitted] • The fatigue limit in the GS diagram was corrected using the BS7608 standard.The fatigue limit in the GS diagram was corrected using the BS7608 standard. • Survival probability was incorporated as an optional parameter in the GS diagram. • Conversion equations of fatigue limits for various cycling characteristics were found. • Construction methods that can be applied to GS diagrams of different structure types were proposed. In this paper, an improved method of Goodman-Smith (GS) fatigue limit diagrams for metallic materials of railway vehicles is proposed. Firstly, this method is based on the three traditional GS curves described in the TB/T 3548–2019 standard, coupled with the S-N curve model from the British BS7608 standard, resulting in improved GS curves applicable to different structural configurations. Within this framework, the survival probability p is introduced as a controllable parameter into the improved GS diagrams, and based on this, the conversion equations of yield strength under different cyclic characteristics applicable to different structures are given for the base metal and the welded structure, which are diametrically opposed in terms of the influence of stress ratios, respectively. Finally, fatigue simulation tests were conducted on the bogie frame to verify and validate the improved GS diagrams. It was found that, while meeting the required criteria, the safety margin at the same survival probability reduced to 0.58 times of the original maximum position. Additionally, the coordinates of the inflection points of the improved GS diagrams for different bogie frame structures and their corresponding design criteria were provided. [ABSTRACT FROM AUTHOR]