On the issue of improving the methodology for confirming maximum safe (design) speed of freight railcars

Abstract

The article provides the analysis of regulatory documents and scientific publications concerning the design speed of rolling stock. The material is provided from the perspective of a methodological approach to establishing the design speed at the level of the maximum value achieved during dynamic and strength tests and track impact tests of the object that meets requirements of technical documentation. Values of strength and dynamic properties of cars obtained during tests performed in track sections with characteristics established in test methods should comply with requirements of regulatory documents. At the same time, during the operation of car running gear, rail geometry and track superstructure, basically have a state that is different from that in which tests were performed. Proceeding from this, in order to ensure traffic safety in operation, permissible speeds are set for tracks of various states and structures. Thus, for freight cars with three-piece bogies, the maximum speed, especially when empty, is limited due to the deterioration of its dynamic properties associated with change in the operation of design parameters and characteristics of bogie elements as well as its rigidity couplings. Due to the deterioration of dynamic properties , the design speed cannot be implemented, including on the track that meets requirements of test methods, on which it was initially confirmed. The maximum permissible speeds of freight cars that are acceptable from the safety point of view are traditionally established based on the results of tests performed since the middle of the last century. When applying innovative freight cars with bogies of a new design, to assess traffic safety, it will be necessary to carry out a large number of tests and to gain operating experience, during which it is necessary to estimate the influence of various factors on traffic safety. In fact, it is necessary to repeat tests to set running speeds, but in a short time, which is very cost-intensive. Based on the foregoing, in order to eliminate the risks associated with safety violation, to confirm the design speed and in order to reduce costs when applying new rolling stock, a full-scale virtual method has been proposed that provides the use of a computer simulation, in which the design speed specified in the technical documentation is set at the stage of rolling stock development, taking into account the operational variability of car running gear and the track state.