# On validation of a wheel-rail wear prediction code

University essay from KTH/Spårfordon

Keywords: wear; code validation; GENSYS;

Abstract:

During the past years, several tools have been developed to try predicting wheel and rail

wear of railway vehicles in an e-cient way. In this MSc thesis a new wear prediction

tool developed by I.Persson is studied and compared with another wear prediction tool,

developed by T.Jendel, which has been already validated and is in use since several years

ago. The advantages that the new model gives are simpler structure, the consideration of

wear as a continuous variable and that all the code is integrated in the same software.

The two models have the same methodology until the part of the wear calculations

and the post-processing. Wheel-rail geometry functions and time domain simulations are

performed with the software GENSYS.

In the simulation model the track and the vehicle are dened as well as other important

properties such as vehicle speed and coe-cient of friction. Three simple tracks are used:

tangent track, R=500 m curve with a cant of ht=0.15 m on the outer rail and R=1000 m

curve with a cant of ht=0.1 m on the outer rail. The model is assumed to be symmetric so

just outer (first and fourth axle) and inner (second and third axles) wheels are considered.

During the vehicle-track interaction, the normal and tangential problems are solved.

The wheel-rail contact is modelled according to Hertz's theory and Kalker's simplied

theory with the help of the algorithm FASTSIM. Then wear calculations are performed

according to Archard's wear law. It is applied in dierent ways, obtaining wear depth

directly in Jendel's and wear volume rate in Persson's model.

Jendel's model is rstly analyzed. Its specifc methodology is briefly explained and

modications are performed on the code to make it work as similar as possible to Persson's

model. Also parameters regarding the distance in which wear calculations are taken, the

discretization of the width of the wheel and the discretization of the contact patch are

analyzed.

The methodology of Persson's model is also studied, most of all the performance of the

post-processing which is one of the keys to the code. The parameters analyzed in this code

are the ones regarding a statistical analysis performed during the post-processing and the

discretization of the contact patch.

Finally the comparisons between the wear depth obtained for both models are carried

out. The discrepancies between the models are explained with the parameters analyzed

and the dynamic behaviour of both models. Also a theoretical case is used as reference for

comparison.