Modélisation par la méthode des éléments finis du comportement dynamique du couple roue-rail.

Abstract

The work presented in this thesis highlights the influence of geometrical singularities on the mechanical behavior of wheel-rail torque. With the increase in the loads transported by axles, the traffic speeds and the state of the tracks, the damage of the wheels is very solicited, leading to more or less serious accidents. The tool used is the ANSYS software based on numerical modeling using the finite element method. The objective of this thesis has been to develop a complete approach to a dynamic analysis of the wheels of the railcar and the wheel-rail pair in contact, allowing to take into account the local demands from the real geometry of the contact wheel- rail, the elastic behavior of the wheel material and the rail (steel) and the operating conditions (load on the wheel and speed). The proposed digital approach deals with two main parts. In the first part, a static analysis was carried out, aiming to model the mechanical behavior of a wheel with different forms of geometrical defects on the tread (circular shape, elliptical shape and any shape, and a perfect wheel), and the wheel-rail pair in contact. In the second part, the dynamic problem of the wheel-rail contact is solved by using the implicit temporal integration scheme. The 3D model developed takes into account only the elastic behavior of the bodies in contact, in the presence of the geometrical defect. However, the central problem in the dynamics of the couple in contact is solved by simplified methods based on the Hertz and Kalker theories implemented in the majority of finite element calculation codes. Finally, a comparative study using a simple modal analysis between the own frequencies of the wheel with and without defect has been proposed. In order to check the vibratory response of these, and to understand exactly how the vibrations may produce minor or catastrophic reactions. However, the different results were validated by an analytical calculation based on the Hertz theory and by some works in the literature.