A Parametric Study Analysing the Effect of Bolster Suspension Parameters on the Carbody Dynamic Response in a Freight Wa
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ORIGINAL PAPER
A Parametric Study Analysing the Effect of Bolster Suspension Parameters on the Carbody Dynamic Response in a Freight Wagon Fitted with Three‑Piece Bogie M. Pandey1 · B. Bhattacharya2 Received: 9 December 2018 / Revised: 8 April 2019 / Accepted: 9 April 2019 © Krishtel eMaging Solutions Private Limited 2019
Abstract Background The carbody of a rail vehicle has different natural frequencies in empty and loaded conditions in different fundamental vibration modes. Moreover, the vertical and lateral track excitation in vertical and lateral directions have several dominant frequency modes. In the case of a freight wagon fitted with three-piece freight bogie, the problem of suspension design is more challenging. The lateral stiffness of the bolster springs is dependent on load, as well as to the spring group height. The damping force is load dependent and is dependent on stiffness/deflection of the bolster springs, the stiffness of the friction control spring (snubber springs) and the coefficient of friction between the surface of the wedge block and the side frame/bolster. There is large variation between the tare weight and the gross weight. Method This paper attempts to analyse the effect of different bolster suspension parameters of a three-piece bogie on the freight carbody dynamic responses in various modes. Multibody models in New and Untried Cars Analytic Regime Simulation (NUCARS) consisting of eleven bodies and seventy connections have been used for the study. The models for empty and loaded wagon contain forty-nine degrees and fifty-two degrees of freedom, respectively. Attempts have been made to validate the simulation models as per the methodology provided by the EN 14363:2016 standard. Effect of 36 bolster suspension combinations has been analysed. Results Snubbing force plays a very important role in the dynamic response analysis. The simulation study suggests that the choice of wedge friction coefficient is challenging as it is affecting the dynamic responses in various modes differently. High coefficient of friction is adversely affecting the vertical and lateral dynamic responses in empty condition and lateral dynamic response in loaded condition. But it is favourably affecting the vertical response in loaded condition. Increase in lateral stiffness is found to be affecting the lateral dynamic response adversely. Selection of the bogie vertical stiffness is very much involved. Conclusion The optimisation of carbody dynamic response for a freight wagon fitted with three-piece bogie can be formulated as a many-objective optimisation problem wherein four of the representative dynamic response acceleration modes, i.e. vertical acceleration on straight track in empty and loaded condition, lateral acceleration on 2° curve in empty and loaded condition, may be selected as objective functions. Keywords Carbody dynamic response · Bolster suspension parameters · Friction control springs · Load-dependent damping · Lateral stiffness · NUCARS
Introduction * M. Pandey [email protected] 1
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