ON SURFACE FRACTURE OF RAIL HEADS
Journal Title: Наука та прогрес транспорту - Year 2017, Vol 0, Issue 4
Abstract
Purpose. The formation of crack-like defects in rails of railway tracks is a serious problem for engineering practice because of the danger of creating emergency situations. The purpose of this work is to establish theoretically the characteristic angle of propagation of surface cracks in the rail heads of railway rails, which is basic in the formation of typical surface contact fatigue damages, such as pitting, «checks» and «squat». It is also necessary to find the conditions for determining this angle. Methodology. The investigations were carried out on the basis of the method of singular integral equations. The rail damaged by the surface crack was modeled with a half-plane with an edge cut, and the action of the wheel on the rail by unidirectional repeated translational movement along the edge of the half-plane of the Hertzian contact forces with the tangential component. The problem of determining the stress intensity factors in the vicinity of the crack tip in the rail head was reduced to a system of two real singular integral equations which were solved numerically by the Gauss-Chebyshev mechanical quadrature method. The complexity of the problem consists in the fact that the boundaries of the contact areas and the opening of the crack faces are unknown beforehand and they change when the model contact forces move. These boundaries were determined simultaneously with solving the integral equations of the problem from additional conditions by the iteration method. Findings. The presence of the characteristic angle of propagation of mode II surface cracks in the rail head has been established theoretically and the conditions for its determination have been put down. The results obtained are in good agreement with engineering and experimental data. Originality. For the first time, the values of the characteristic angle were theoretically determined, under which at the initial stage, the surface contact fatigue cracks propagate in the head of the railway rail under the action of the wheels. Conditions for determining this angle have been also put down. Practical value. The received data are of great importance for engineering practice, since they reveal the nature of surface contact fatigue defects under various operating conditions and allow to predict their contact strength and durability.
Authors and Affiliations
O. P. Datsyshyn, H. P. Marchenko, A. Y. Glazov
Keywords
Related Articles
- EP ID EP232174
- DOI 10.15802/stp2017/109539
- Views 91
- Downloads 0
RESEARCH PREMATURE DESTRUCTION OF CONCRETE SLEEPERS ON THE MAIN LINES OF PUBLIC COMPANY «UZ»
Purpose. The study aims to identify the causes of premature destruction of concrete sleepers of one of Ukrainian producers. Methodology. Applied microstructural, fractographic, X-ray microanalysis revealed causes of tran...
THE SUBGRADE HETEROGENEITY CONSIDERATION OF A RAILWAY TRACK WHEN DETERMINING ITS STRESS-STRAIN STATE
Purpose. Increase of the speed and train carrying capacity causes the increase in the load on the railway track and, in turn, loads on the subgrade. This makes it necessary to clarify the calculation methods, both the up...
CALCULATION OF MAGNETIC CHARACTERISTICS OF TRACTION ELECTRIC ENGINE WITH THE USE OF IMPROVED UNIVERSAL MAGNETIC CHARACTERISTICS
Purpose. The article is aimed to develop a technique for calculating the magnetic characteristics of uncompensated traction electric motors (TEM) at any degree of attenuation of excitation based on the approximating expr...
ЗАЛЕЖНІСТЬ ВЕЛИЧИНИ ЗНОСУ ПАРИ ТЕРТЯ «П’ЯТНИК – ПІДП’ЯТНИК» ВІД ПРОБІГУ ВАНТАЖНОГО ВАГОНА
Мета. Дослідження спрямоване на розгляд взаємодії циліндричних поверхонь пари тертя «п’ятник – підп’ятник» вантажного вагона. Необхідно теоретично дослідити процес зносу та отримати залежність величини зносу підп’ятника...
DETERMINATION OF THE LOADING OF CONTAINERS IN MIXED TRAINS WHEN TRANSPORTING BY TRAIN FERRIES
Purpose. The study is aimed at determination of the loading of containers in mixed trains when transporting by train ferries. Methodology. In order to achieve the objective the author studied accelerations (as components...