Characterising stochastic friction in railway draft gear

Abstract

The draft gear is a key component in a railway train system. The stochastic feature of dry friction in the draft gear has been observed by many researchers, however, characterisation studies in this regard have not been published. This paper used a state-of-the-art laboratory testing rig to measured draft gear forces and deflection responses to sinusoidal force inputs. Measured data were then inversed into values for Coefficient of Friction (CoF). The inverse method was developed based on a friction-wedge-spring draft gear model. The results show that CoF values have a range from 0.22 to 0.47; however, the majority of values are located above 0.34. Normal distribution fitting of the CoF values show that they have a mean of 0.42 and a deviation of 0.02. Weibull distribution fitting shows that they have a scale parameter of 0.43 and a shape parameter of 22.48. The normal distribution stochastic friction was used to model a friction draft gear. A simulation was conducted, and the results show that simulations using the stochastic model can better match the measured data than using conventional deterministic friction.