Some new contributions to the resolution of the normal wheel-rail contact problem

In the majority of railway dynamic simulator programs, the Hertz theory is used for solving the normal wheel-rail contact problem. This theory provides good results in the most common situations; however, its results are not satisfactory in situations such as the solution of non-elliptical contact areas, the multi-contact conditions and the transition from two to one contact area. In a previous paper, Alonso and Gimenez [Alonso, A. and Gimenez, J.G., 2005, A new method for the solution of the normal contact problem in the dynamic simulation of railway vehicles. Vehicle System Dynamics, 43, 149-160.] showed that the square root simplified theory (SRST) allows solving the normal contact problem for general undeformed distance profiles with enough accuracy. In this paper, the SRST method is modified in order to solve accurately multi-contact situations, including the union and separation of two contact areas. The results obtained are acceptably precise for most rail applications