In the analysis of the railroad dynamics the study of the wheel-rail contact represents a very important role because it not only conditions the motion of the vehicles on the track, with associated phenomena such as stability or comfort, but also leads to degradation phenomena such as wear associated with low frequency (wear in the profiles) o high frequency (corrugation on rails) or rolling contact fatigue phenomena.

After studying the available literature related to the wheel-rail contact, in this Thesis a model to solve the whole contact problem has been developed and implemented, whose application is the dynamic simulation and the estimation of wear on the low frequency range. This model takes into account the three-dimensional geometry of the wheel-rail contact and it estimates the contact area from the virtual interpenetration between profiles. To solve the normal problem, an equivalent ellipse to the non-elliptic contact area is defined and a normal stress distribution following the theory of Hertz is assumed. The tangential problem is solved for the equivalent ellipse with the option of incorporating a variable coefficient of friction.

The development of this contact model is accompanied by experimental results that lead either to validate the numerical results obtained with the application of the contact model or to parameterize these models to consider different conditions in the contact. On the one hand, the ultrasound technique is used, applied to the study of the contact between metallic surfaces. This technique allows for the obtaining of the shape and size of the contact area and an estimate of the distribution of normal pressures. On the other hand, creep curves measured experimentally in a twin-disc machine are used to extract the parameters that define the tangential behaviour of the wheel-rail contact under different conditions: dry surfaces, wet surfaces, surfaces with oil, with friction modifiers, etc.

Finally, the model is applied in the dynamic simulation where the effect of considering a variable coefficient of friction against the classical method of constant coefficient of friction is assessed. In addition, the wear results obtained with the two existing wear algorithms (local/global) are compared.