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The wheelset and its components (the axle and the wheel) are subject to technical regulation. Therefore, in order to establish the assigned service life in accordance with TRCU 001/2011 (Technical Regulations of the Customs Union) and the examination frequency taking into account the durability parameters of rolling stock components in accordance with VNIIZhT RD 27.05.01-2017, it is necessary to assess the operational loading obtained from the running testing results, with respect to the part strength characteristics which are calculated during the bench tests. At present, to estimate the stress-strain state (SSS) in various machine-building structures, the strain measurement method is widely used, which allows to assess their performance with high accuracy. However, determining the SSS of a wheelset is not only a difficult task due to the constant rotation and movement of the wheelset relative to the bogie, but also expensive due to the employment of special non-contact measuring systems. Development of a dynamic model using modern software systems allows determination the stress-strain state of the wheelset elements by creating dynamic models as a system of perfectly rigid and elastic bodies connected by strength members and hinges. To confirm the adequacy of the parameters obtained in the simulation, verification is carried out according to the results of running dynamic strength tests. Thus, using the obtained model of the rolling stock and the track it is possible to make life and durability assessment as well as optimize the main rolling stock components. On the example of a freight gondola car model, a diagram of the dependence of dynamic stress amplitude distribution on the frequency of the occurrence in the wheel has been obtained, and considering the results of the earlier bench tests of standard specimens and full-scale wheels the period has been determined for durability from the moment of crack initiation in the wheel up to its fracture, as well as the assessment of the safety factor for durability is given.

The deterministic evaluation of the durability of railway rolling stock structures according to fatigue safety factors, established by regulatory requirements, does not fully take into account the random nature of loads that cause the accumulation of fatigue damages, the operation rate (operating time), does not allow to evaluate the operating life and its depletion over the service lifetime. At the same time, with the development of heavy and high-speed traffic, as well as due to the introduction of technical regulations, the task to evaluate and substantiate the assigned service lifetime and operating life of railway vehicles are becoming more important. The subject of the study, the results of which are presented in this article, was the fatigue strength of elements of locomotive basic parts. The purpose of the work was the prediction of their limit state by the operating life of critical elements. In the present work, design and experimental studies have been performed with running dynamic and strength tests of the locomotive in the entire range of operating speeds of its running, determining the stress-strain state of structures using strain-gauge methods, calculating safety factors with the probabilistic estimate of the fatigue strength of parts. According to results obtained, the influence of the operation loading performance on the fatigue strength margin and its depletion during the element operating life is shown. According to the results of this work, it can be concluded that main indicators of the strength, operating life and service lifetime of the locomotive make it possible to compare and link their key parameters for the subsequent analysis, substantiation, rating and control of safe operating life of railway equipment.