Research On Goodman-Smith Fatigue Method And Its Application In Rail Vehicles

The extensive use of welded structure effectively reduces the dead weight of the bogie frame,and the fatigue strength check of welded structure is the key content of product design.In order to apply the Goodman-smith fatigue method to the fatigue strength evaluation of welded structures,this paper improves the Goodman-Smith fatigue limit diagram by combining three typical joints.Taking a certain type of bogie frame as the research object,static strength analysis,modal analysis and Fatigue analysis,mainly to complete the following contents:First of all,the current situation of bogie fatigue assessment at home and abroad is studied,and the fatigue development process,common methods and standards of fatigue assessment are briefly introduced.Secondly,the Goodman-Smith fatigue method is deeply studied,and the source,drawing principle and drawing method of the Goodman fatigue limit diagram are clarified.The finite element models of three typical joints were established,and the fatigue limit diagram provided in UIC ORE B12/RP17 standard and the fatigue limit provided by BS standard were used to evaluate the fatigue strength of welded joints.The evaluation criteria are too loose.The fatigue limit diagram was improved according to the data provided by the BS standard,and the improved 8-sided Goodman-Smith fatigue limit diagram was obtained,and the fatigue strength of three welded joints was evaluated using the improved fatigue limit diagram.The calculation results and the results before improvement in contrast,the results show that: using the BS standard fatigue data to improve,effectively improve the accuracy of the fatigue limit diagram for the fatigue assessment of welded structures.Thirdly,combined with UIC 615-4 standard and JIS4208 standard,the static strength analysis is carried out,and the modal analysis is carried out on the unconstrained model.Finally,three methods are used to analyze the fatigue of the key welds.The calculation results show that the fatigue evaluation results of the bogie using the improved fatigue limit diagram are closer to the evaluation results of the BS standard.Through the improvement of the Goodman-Smith fatigue method,the safety factor obtained by the Goodman-Smith fatigue method is reduced from 2-3 times of the BS standard safety factor to about 1.1 times before reaching the tensile pulsation cycle.Goodman-Smith fatigue limit diagram for structural fatigue strength assessment.The research content of this paper provides a theoretical basis for the fatigue strength evaluation of welded structures,and has important engineering significance for the fatigue design of rail vehicle bogie frames.