Title: Studies on critical hunting speed and running safety of conventional railway vehicles moving on curved tracks

Authors: R.K. Sajeev; Sujatha Chandramohan

Addresses: Machine Design Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai – 600036, India ' Machine Design Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai – 600036, India

Abstract: Railway vehicle critical hunting speed (CHS) and running safety are factors to be vitally investigated for the study of its dynamic behaviour. In this paper, a numerical investigation of the nonlinear dynamic behaviour of a railway vehicle running on tracks of various radii is carried out using a mathematical model of the vehicle-track combined system. Using single and two point contact scenarios, nonlinear CHS and running safety of the vehicle are evaluated. The model consists of a 25-degrees-of-freedom system with four wheel-sets, two truck frames, two bolsters and a carbody. The track is idealised as a laterally flexible spring-mass-damper system. The model is solved for the dynamic response in the time domain using Runge-Kutta fourth-order method. Limit-cycle-type oscillation is adopted to evaluate the nonlinear CHS. Furthermore, the influence of material and wheel/rail geometric parameters on vehicle running safety are presented, which is based on derailment quotient and offload factor.

Keywords: CHS; critical hunting speed; running safety; single/two-point wheel-rail contact; nonlinear creep model; curved tracks.

DOI: 10.1504/IJHVS.2021.121807

International Journal of Heavy Vehicle Systems, 2021 Vol.28 No.6, pp.808 - 845

Received: 28 Apr 2020
Accepted: 29 Nov 2020
Published online: 07 Apr 2022 *

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