Influence of the Axle Box Elastic Element on the Life of the Bogie Side Frame at 25 Tonnes Axial Load

Purpose: To assess the influence of the elastic elements of the axle box unit in the 18-9891 model bogie on the service life of the side frame based on the digital modelling, experimentally determined fatigue limits and the results of running tests. Methods: Running-dynamic-strength tests, accelerated bench tests of the fatigue strength of the bogie side frames, dynamic digital modelling using the Universal Mechanism software product. Theoretically obtained dependencies of the dynamic coefficient of the unsprung parts and the experimentally obtained values of the fatigue limit allowed determining the influence of the elastic connection in the axle box unit on the dynamic stress equivalent amplitude. Results: Based on the results of the digital dynamic modelling, the dependencies of the vertical dynamics coefficient of the bogie unsprung parts, both in a loaded and in an empty car, on the elastic bracket deflections in the axle box unit were obtained. The fatigue limit and the amplitudes of the dynamic stresses for the side frames with elastic elements in the axle box unit were determined experimentally, from which the service life of the side frames was predicted. The discrepancy between the experimental data on the dynamic stress coefficient of the unsprung parts of the bogie and that of the digital modelling showed that the results converged within 5-8%. Based on theoretical and experimental studies, the influence of the elastic brackets in the bogie axle box unit on the service life of the side frames has been estimated and the possibility of reducing their metal consumption has been demonstrated. Practical significance: The increased service life of the bogie side frame with elastic elements has been confirmed, and the possibility of increasing the service life and inter-repair runs for the 18-9891 freight bogie according to the criterion of the fatigue limit of cast elements has been demonstrated. The possibility of reducing the metal consumption of the side frame has been demonstrated.