From the third body layer modeling to its effect on railway vehicle dynamics
Kalker’s rolling contact theories allow good estimation of the creep forces only for situation with scrupulously clean surfaces. When wear particles mix with the substances added naturally or artificially, a Third Body Layer (3BL) is formed at the wheel-rail interface. This layer influences the initial slope of the creep force characteristic. A 3D finite element model is developed in this paper to study the wheel-rail rolling contact in the presence of a thin elastic 3BL at the rail surface. The result shows reduction in the initial slope of the creep forces characteristic i.e. Kalker’s coefficients. In order to evaluate the effect of the 3BL on railway vehicle dynamics, a reducing factor K is evaluated from the creep curve then applied to the multibody software VOCO. The study of derailment shows a slight decrease of the peak of Y/Q ratio which remains above Nadal criterion. However, the critical speed of the vehicle is considerably reduced when the factor K is applied.