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Analysis of the conditions for the exhaustion of the stability margin in the rail track of freight cars with three-piece bogies

Domin Yurii V., Domin Rostysla Yu., Cherniak Ganna Yu., Nozhenko Volodymyr S.

Archives of Transport

2021

Vol. 57, iss. 1

119--129

The research on improvement of methodical approaches to definition of the probable reasons of infringement of conditions of stability of freight cars from derailment is carried out. Using a basic computer model of the dynamics of a freight car, the influence of the characteristics of the technical condition of their running gear and track on the indicators of empty cars stability from derailment was studied through the computational experiment. The article presents the main statements of the research methodology, which provides the analysis of probable causes of derailment of freight cars by conducting a series of numerical experiments with logging the progress of calculations and saving the results. Factor analysis was used to interpret the calculated data with an assessment of each of the factors influence or their combination on the probability of derailment. The developed procedure of the simulation experiment provides a step-by-step study of the freight cars derailment conditions, including factors structuring and ranking, development of experimental plan, calculating coefficients of wheel pairs resistance to derailment from rails, provided that the wheel flange rolls onto the rail head, and determining the degree of influence of relevant factors on the dynamic stability of cars from derailment. A comparative analysis of the stability of cars in rail tracks was performed using the introduced concept of the combined coefficient of stability of wheel pairs against derailment. Determining the probable causes of car derailment is based on scanning the parameter field. The results of the parametric study revealed the degree of influence on the freight cars stability of running gear technical condition characteristics. In particular, it is determined that the most dangerous in terms of stability loss of empty cars in the track is the exceeding of the wedges of the vibration dampers.

Use of piezoelectric foils as tools for structural health monitoring of freight cars during exploitation

Płaczek M., Buchacz A., Wróbel A.

Eksploatacja i Niezawodność

2015

Vol. 17, no. 3

443--449

Work presents a task of piezoelectric foils application for structural health monitoring of freight cars during their exploitation. Results of laboratory tests conducted on a created in scale laboratory model of the freight car are presented. The possibility of inferred from the dynamic response of the model about the changes in its technical condition was verified. During the first test the model was treated as a half-determined system. In order to excite vibrations a pendulum was used. Measurements were carried out using accelerometers. During the next stage of carried out tests the dynamical response of the model was measured while the object was driving. In order to measure vibrations of the system a Macro Fiber Composite (MFC) piezoelectric foil was used. It was glued on the surface of the model. A series of tests of the model with and without load, as well as with an obstacle on the rail track was carried out. Measured signals were juxtaposed on charts and analysed.

W pracy przedstawiono zagadnienia dotyczące zastosowania folii piezoelektrycznych do monitorowania stanu technicznego wagonów towarowych w trakcie ich eksploatacji. Przedstawiono wyniki badań laboratoryjnych prowadzonych na utworzonym w skali modelu węglarki. Określono możliwość wykrycia zmian stanu technicznego wagonu na podstawie analizy jego odpowiedzi dynamicznej. W pierwszym etapie badań obiekt traktowano jako półokreślony, w celu wymuszenia drgań stosowano wahadło. Pomiar odpowiedzi dynamicznej układu w poszczególnych punktach pomiarowych przeprowadzono z użyciem akcelerometrów. Kolejnym etapem badań był pomiar odpowiedzi dynamicznej modelu w trakcie jazdy. W celu pomiaru drgań konstrukcji nośnej modelu zastosowano przetwornik piezoelektryczny typu Macro Fiber Composite (MFC), który naklejono na powierzchni modelu. Przeprowadzono ciąg badań modelu bez obciążenia oraz z obciążeniem, a także z przeszkodami umieszczonymi na jednej bądź obu szynach. Otrzymane przebiegi zestawiono na wykresach oraz omówiono wyniki badań.