Numerical simulation of track settlement using a multibody dynamic software a holistic approach

The increase of train loads, axel loads and operational speeds, contribute to increased degradation processes of the track, particularly in critical sections such railway turnouts, leading to the initiation and development of damage mechanisms. The increased track degradation means that it is necessary to intensify the frequency and the amount of maintenance works in the critical track sections, resulting in increased costs for the infrastructure manager. The fundamental idea of this work is to create and implement a novel methodology to analyse the train/track dynamic interaction and its influence on the overall track settlement mechanism of any track section. This will be achieved by creating an iterative loop that makes possible toassess the condition of the track based on the vehicle forces. This concept enables firstly, to keep the computational advantages of multibody codes when contact behaviour between the wheel and the rail is assessed. The main contribution of this work rests on performing a track degradation analysis considering a regular stretch of railway track, in which the abovementioned methodology is implemented. In the first phase, a train/track interaction analysis is developed and assessed by evaluating the contact forces between the wheeland the rail. In a second phase, the forces at each particular support, beneath the rail, are extracted and transformed, by applying a degradation law at the ballast layer, into vertical displacements that in turn are applied as longitudinal level irregularities in the rail. The process is completed by including the updated geometry that enables the further calculations, in a loop mode, considering as many cycles as required. In light of the foregoing, this work presents an efficient and novel technique that enables a commercial MBS (Multibody Simulation Software) to iteratively predict the impact of the accumulated track settlement on the train/track interaction.