Studying the Railroad Track Geometry Deterioration as a Result of an Uneven Subsidence of the Ballast Layer

A method for calculating impairment of the track geometry under influence of dynamic loads in the course of passing the track unevenness by the rolling stock was developed. The method takes into consideration interrelated short-term processes of dynamic interaction and long-term processes of subsidence of the ballast layer in a mutual influence on each other. Mathematical model of dynamic interaction of the track in the form of a planar three-layer continual beam system with a two-mass discrete system corresponding to the rolling stock is the basis of the first part of the method. This model makes it possible to simulate dynamic loads from individual sleepers to the ballast when the rolling stock passes geometric unevennesses and the track elasticity unevennesses.The second part of the method is based on the phenomenological mathematical model of accumulation of residual deformations formed using the results of laboratory studies of subsidence of individual sleepers in the ballast layer. Peculiarity of this model consists in taking into consideration not only uniform accumulation of residual subsidence from the passed tonnage but also presence of a plastic component of subsidence which depends on the maximum stresses in the history of ballast loading by each sleeper.A new theoretical mechanism of development of the track unevenness was proposed. It takes into consideration not only residual subsidences of the ballast layer but also appearance of gaps under sleepers resulting in a local change of the track elasticity. This mechanism enables taking into consideration the ambiguous influence of subsidences with occurrence of gaps under the sleepers. Subsidence causes an increase in dynamic loads on the track and the ballast layer on the one hand and onset of the gap causes a decrease in the track rigidity and corresponding reduction of dynamic loads on the other hand.Practical application of the developed method was demonstrated on an example of quantitative estimation of long-term uneven subsidences of the ballast layer when changing the sleeper diagra

Development of a Promising System for Diagnosing the Frogs of Railroad Switches Using the Transverse Profile Measurement Method

We have developed a system for diagnosing the frogs of railroad switches, based on the application of modern microcontrollers of the type ESP with high technical characteristics and the simultaneous use of the information technology IoT (Internet of Things). The proposed system has advantages over mechanical systems in terms of the accuracy of data, their operational processing and submission to user in order to analyze technical condition of frogs at railroad switches. The results of measuring the transverse profile of frogs at railroad switches make it possible to take scientifically-substantiated decisions regarding the need for recovery repair of frogs by the method of surfacing and for control over gradual decrease in their carrying capacity, for establishing their actual technical condition and residual resource.We carried out experimental-theoretical research into longitudinal profile of frogs at railroad switches laid on the reinforced concrete bars. It was established as a result that after passing 50–65 million tons of cargo (that corresponds to the medium degree of wear) the trajectory takes the shape of a bump. We observe sharp hollows on the reinforced concrete base in the zone where a wheel rolls from a rail wing onto the core, characterized by significant total inclination. Subsequently, when the passed cargo increases, the number of sinusoidal irregularities grows. At wear close to maximal (80–95 million tons passed), the percentage of unfavorable trajectories (sinusoidal and hollows) grows; at low wear, they make up 49.8 %, at a wear of 5–6 mm and larger – 88.3 %. Sometimes there is a transformation of the sinusoidal irregularities into the wave-shaped ones.We have established characteristic motion trajectories of the center of mass of the wheel over the frog depending on the wear of rail wings and the core of a frog and the passed cargo. A mathematical model was constructed for predicting the wear of frog profile depending on the total weight of passed cargo

Theoretical Study Into Efficiency of the Improved Longitudinal Profile of Frogs at Railroad Switches

We have developed a comprehensive method to prolong the time of operation of frogs at railroad switches, based on the consideration of a longitudinal profile of the frog, the magnitude of dynamic forces and normal stresses.We have improved a longitudinal profile of the frog, brand 1/11, project 1740, by the method of surfacing under field operation conditions. The slopes of a trajectory after the passage of an average statistical wheel over the proposed profile amount to 3.7 ‰ instead of 10 ‰ for a standard profile of the frog.It was established that increasing a load on the frog to 60 % at the expense of a deflection under the frog beam leads to the accelerated disarrangement of the frog, as a result of fatigue defects at the rolling surface, while the cost of frog operation in this case increases by five times.We modeled a dynamic interaction between the rolling stock and a standard, as well as the proposed, longitudinal profiles of frogs. Calculation of dynamic processes of the nonlinear interaction between the rolling stock and a standard profile of the frog and the profile restored by surfacing, showed that the magnitude of forces for the proposed frog at the motion speed of 150 km/h is 50 % lower compared with a standard longitudinal profile. At linear simulation of dynamic additions of forces, the magnitude of forces decreases for the proposed profile to 30 %.We employed a graphical method to calculate the magnitudes of axial inertia moments and the moments of resistance in the characteristic cross sections of the frog. The estimation of the stressed-strained state of the frog was performed using equations of five moments for a continuous beam on elastic point supports. It was established that stresses at the static calculation of the frog are low and are much less than the maximum permissible magnitude of stresses for a given grade of steel. Therefore, we can argue that the frog works under a load at the expense of existing reserve of strength

Исследование динамических колебаний балки на упругой диссипативной основе под действием подвижной нагрузки при прохождении силовой неровности пути

Сисин, М. П. Дослідження динамічних коливань балки на пружній дисипативній основі під дією рухомого навантаження при проходженні силової нерівності колії / М. П. Сисин, В. В. Рибкін, О. М. Патласов // Вісн. Дніпропетр. нац. ун-ту залізн. трансп. ім. акад. В. Лазаряна. — 2004. — Вип. 5. — С. 188—193.UK: У даній статті розглядається модель залізничної полотнини, що являє собою балку на пружній інерційній підставі під впливом квазистатичного навантаження, що рухається. Дослідження цієї моделі проводиться в умовах руху навантаження на колію з неоднорідністю гнучкості основи під рейками.RU: В данной статье рассматривается модель железнодорожного полотна, которая представляет собой балку на упругом инерционном основании под воздействием движущейся квазистатической нагрузки. Исследование этой модели проводится в условиях движения нагрузки на пути с неоднородностью гибкости основы под рельсами.EN: A railway track model is considered in this paper. The model is a beam on elastic inertial basis with variable longitudinal elasticity under the influence of moving quasistatic loading. The investigation of the model is carried out on conditions that the loading moves on the track with the inhomogeneity of basis elasticity under the rail