Speaker
Description
Magnetic Track Brakes (MTBs) are used in railway systems as emergency braking mechanisms that involve mechanical contact between a braking element (pole shoe) and the rail. Accurate prediction of both local and global contact forces and associated deformations occurring during braking is essential for optimizing the performance of the overall braking system. To this end, it is necessary to develop a precise and computationally efficient sliding contact model that can later be used to study the multibody dynamics of the entire braking system.
The proposed model uses quasi-static assumptions to simplify the complex contact dynamics, further, it is relying on an elastic half-space theory for localized contact interactions. The study focuses exclusively on mechanical loading, excluding electromagnetic forces for the sake of simplicity and also because the source of the loading whether it is mechanical or electromagnetic is irrelevant for the demonstrated model and effects. The model employs a quasi-rigid body approach, allowing overall rigid body motion while permitting localized elastic deformations at the contact surfaces only. The elastic half-space theory is used to enhance computational efficiency, eliminating the need for extensive parameter identification, which often requires costly experimental studies. The model incorporates Coulomb friction for sliding interactions and simplifies computation by pre-calculating matrix coefficients for undeformed states, making it highly efficient for quasi-static simulations.
The variation in the contact pattern formed on the contact surface of the pole shoe sliding at different speeds on a frictional surface, as well as the distribution of forces across this surface, has been investigated. Comparisons of the obtained results against finite element simulations show good agreement in the global force distribution on the contact areas but highlight limitations at the boundaries where stress concentrations occur. The comparisons indicate that this approach significantly reduces computational effort while maintaining a balance between accuracy and efficiency. Additionally, the parametric analysis explores how changes in the pole shoe's motion and loading conditions affect the numerical results, emphasizing the model's efficiency and practicality for scenarios with small elastic deformations. The model demonstrates strong applicability for integration within multibody dynamic simulations, offering an efficient tool for evaluating MTB performance under operational conditions.
