Regularization in the governing equations of railway wheel models

In this article it is shown for the formulation of contact kinematics that continuity requirements are necessary. To guarantee the continuity, material damping (relaxation time t) terms must be taken into account, i.e., the corresponding equations are regularized. Furthermore, it is shown that a boundary layer occurs always behind the point of contact (velocity v) and that the characteristic length of the boundary layer is tv. Because of the little influence of the boundary layer it can be concluded that the material damping can be dropped as a mean of regularization if the norismooth velocities are calculated in front of the point, of contact. Thus the numerical treatment of railway wheel models can be simplified.