Determination of characteristics of fatigue cracks growth in the axles of railway carriages
Ескіз недоступний
Дата
2023
DOI
doi.org/10.20998/2079-0775.2023.2.13
Науковий ступінь
Рівень дисертації
Шифр та назва спеціальності
Рада захисту
Установа захисту
Науковий керівник
Члени комітету
Видавець
Національний технічний університет "Харківський політехнічний інститут"
Анотація
Providing damage resistance is the most important requirement presented to railway axles. This paper provides a detailed review of the characteristics of resistance to fatigue crack growth in axles made of EA4T steel (25CrMo4). This steel is typical for axles of high-speed rolling stock. Resistance to fatigue crack growth is defined by the nature of the Paris-Erdogan curve da/dN=CKm, the parameters of which are the coefficient C and the exponent m. Determination of these parameters is based on the results of fatigue tests with the samples or with full-scale axles having cracks. The analysis of numerous scientific papers has shown that for the specified steel there is a significant scatter in the values of these parameters. This scatter is caused by a number of factors, the main of which are: the difference in test objects (from small samples of the SE(B) type to full-scale rolling axles 190 mm in diameter); the difference in loading methods (tension-compression, flat bending, circular bending); the variation of mechanical properties of EA4T steel. In the paper the models of surface fatigue crack geometry are analyzed and semi-elliptical shape of crack front line is selected as the most acceptable. The significant scatter in the values of the parameters m and C prevents to establish reliably the residual life of axles with cracks, which is an important characteristic for practical forecasting of axle survivability. The technique for parameters m and C optimization in view of semi-elliptical shape of the crack front line has been developed. The relationship linking the parameters m and C has been established. The method for determining the residual life of the axle by the criterion of non-destruction is proposed. The dependence between the residual life and the value of the parameters of the Paris-Erdogan equation in the development of fatigue failure is established. The procedure for axles monitoring timeframes setting to prevent their fatigue failure is discussed.
Опис
Ключові слова
parameters of Paris-Erdogan equation, fatigue crack, residual life of axle, параметри рівняння Періса-Ердогана, втомна тріщина, залишковий ресурс осей
Бібліографічний опис
Khomiak Yu. Determination of characteristics of fatigue cracks growth in the axles of railway carriages / Yu. Khomiak, O. Kibakov, I. V. Gerasymov // Вісник Національного технічного університету "ХПІ". Сер. : Машинознавство та САПР = Bulletin of the National Technical University "KhPI". Ser. : Engineering and CAD : зб. наук. пр. – Харків : НТУ "ХПІ", 2023. – № 2. – С. 122-128.