Corrugation On Railway Rails - A Linear Model For Prediction

Abstract

A model is presented to predict the initial phase of the formation of corrugation. The basic idea of the model is a feedback loop between high-frequency dynamics of wheelset and track coupled by the contact mechanics and a damaging process (wear). The model allows for the prediction of local corrugation growth rates, corrugation patterns along the rail with corresponding amplitude spectra and global corrugation growth rates. Parameter studies are presented to show the influence of track and wheelset on the formation of corrugation. 1 The corrugation model Fig 1 shows the basic idea of the corrugation model following ideas of Valdivia [1] and Frederick [2]. The vehicle system dynamics are introduced into the model by a reference state which is quasi static for a linear highfrequency dynamics model. This reference state supplies reference normal and tangential forces as well as reference creepages, contact geometry and vehicle speed. These values are taken to be the point of linearization of the model. The structural dynamics are excited by the initial profile irregularities. They cause fluctuating forces and contact parameters. These fluctuating forces and contact parameters produce fluctuating wear assuming the proportionality between frictional power and wear (frictional power hypothesis). The fluctuating wear will change the profile irregularity filtering certain wavelengths to become what is known as corrugation. The initial profile irregularities are represented by Fourier series and each of the Fourier wavelengths Lk is treated separately. Regarding only the vertical and Transactions on the Built Environment vol 6, © 1994 WIT Press, www.witpress.com, ISSN 1743-3509