Prediction of dynamic forces exerted on ballasted railway tracks

Description :

The prediction of the dynamic forces or the forces of contact between the wheels of the trains and the rail will lead to determine the stresses within the rail and consequently estimate the life-time of the rail. In order to do this, analytical and numerical modeling will be proposed in order to provide the relation between the applied forces and the response of the rail. Usually, the researchers in this domain expect to determine the response of the track based on an applied given force, however the present case is an inverse problem that requires to determine the applied dynamic forces based on pre-known acceleration that is obtained by on-site measurements. This work will be conducted in cooperation with Professor Denis DUHAMEL from Ecole des Ponts (Paris-Tech – France) and it can be done based on the following phases. Phase 1 will be considered as a literature review that consists in exploring all previous and recent research work that deals with inverse problems and railway modeling. In phase 2, the railway track will be modeled as an infinite Euler-Bernoulli’s and then a Timoshenko beam supported by a set of springs and dampers that depends on the components of the track. The related governing equations of motions can be written based on the adopted model and then solved analytically or numerically for the unknown dynamic force based on given displacement, velocity, or acceleration. In phase 3, models can be improved by including nonlinearities and visco-elastic behavior of some components in the track such as ballast and pads. Phase 4 consists in the validation of the model, finite elements software such as ABAQUS may be used in order to validate the analytical or the numerical solution, the determined force can be now applied on the rail and the problem can be solved based on the proposed models in order to determine the response of the rail that will be then compared with the measured response for validation. Phase 5 may be dedicated for the determining of the dynamic stresses in the rail and the estimation of its life-time. It could be also a good PhD subject to be proposed for the coming academic year.