Koshel O. Forecasting the remaining resource and extending the service life of the load-bearing structures of the special rolling stock of railway transport

The dissertation is devoted to the solution of an actual scientific question regarding the possibility of determining the residual resource and extending the period of operation of the load-bearing structures of the special rolling stock of railway transport (dump cars and hopper-dispensers) for further safe operation during the shortage of freight rolling stock in JSC «Ukrzaliznytsia». This dissertation work is devoted to the forecasting of the residual resource of load-bearing structures and the extension of the service life of special rolling stock of railway transport and is relevant for the railway industry, in particular, ensuring the safe operation of this type of rolling stock. Scientific novelty of the obtained results. For the first time, it was proposed as an additional design mode for loading elements of load-bearing structures of dump cars in the process of studying their strength, a mode that simulates the case of loading a structure in the event of a failure (jamming) of one of the pneumatic unloading devices, given that even with a single load in this mode, to take place the initiation of primary fatigue cracks at the most stressed points. Improved: - the principle of determining points of control of stress parameters during experimental studies of the strength of dump wagons based on taking into account data on fatigue defects of load-bearing elements during operation; - a scientific approach to the methods of increasing the structural strength of the elements of load-bearing structures of dump cars and hopper-dosers – based on the analysis of additional stress concentrators that arise after the strengthening of dangerous intersections. - a formula for predicting the maximum service life of wagons, based on taking into account experimental data of stress measurements and stresses obtained during 3D modeling; - the effective coefficient of stress concentration, which takes into account the reduction of fatigue resistance by introducing correction coefficients at each measurement point in comparison with the data obtained by the calculation method in the area in close proximity to the point of gluing the strain gauge. The theory of fatigue strength was further developed based on the consideration of the mechanism of formation of primary defects in the elements of load-bearing structures, which caused the initiation of fatigue cracks, based on the statistical analysis of excess structural loads of the structure during operation. Practical significance of the obtained results: - proposed additional (emergency) calculated mode of loading of load-bearing structures of dump cars during the study of their strength, which simulates the case of structural loading in case of failure (jamming) of one of the pneumatic unloading cylinders, in which case primary fatigue cracks may appear at the most stressed points; - a new design and technical solution for improving the construction of dump cars; - a refined formula for predicting the maximum service life of wagons, based on the combination of experimental stress measurement data and stresses obtained during 3D modeling; - on the basis of the results of strength calculations, changes are proposed to the Internal regulatory document DW-0033. The main results of the dissertation have been implemented: - at the branch «SEI» of JSC «Ukrzaliznytsia» in carrying out strength calculations and analysis of malfunctions of special rolling stock wagons, writing programs and techniques for technical diagnostics of dump cars and hopper-dispensers with the aim of extension of the period of operation; - the program and technique of technical diagnostics of dump cars, strength calculations, analysis of malfunctions of wagons of special rolling stock in the educational process of the SUIT at the department «Wagons and wagon management» in the lecture course of the educational component «Reliability and technical diagnostics of freight cars» for the preparation of students of the 2nd educational degree Master's degree in specialty 273 «Railway transport»; - at the DW of JSC «Ukrzaliznytsia» during the design of new dump cars, strength calculations of the lower frame of the wagon, the method of increasing the structural strength of load-bearing structures, engineering solutions when writing normative documents for the implementation of planned types of repairs. According to the topic of the dissertation, the following were published: 4 scientific articles in Ukrainian publications, which are included in the list of scientific specialized publications approved by the MES of Ukraine, 1 scientific articles in publications indexed in the scientific-metric databases Scopus, 8 articles and abstracts of reports, which additionally reflect the results of the work, 1 patents of Ukraine for the utility model and 1 copyrights for the work.