Thermomechanical characterization of high-speed train braking materials to improve models: Numerical validation via a comparison with an experimental braking test

Abstract

Today, the development of brake pads is carried out by empirical feedback validated by experimental bench tests. Nevertheless, these test campaigns are time-consuming, costly and ultimately do not help to understand phenomena for improving performances (coefficient of friction, durability, noise, etc.). To overcome these limitations, numerical braking models have been developed for several years. They need to be representative of the experimental reality in order to predict the current performance of brake systems and ultimately improve them. The difficulties, especially for high energy dissipation applications such as high-speed train (HST) braking systems, lie in the fact that thermomechanical coupling is important to consider, which particularly affects the behaviour of brake linings. According to the literature, this thermomechanical evolution is not sufficiently taken into account. In this work, a complete methodology is proposed for the identification of the behaviour of friction materials under coupled mechanical and thermal loads. In a second step, the properties obtained are injected into a simulation of a real and representative braking system. An experimental test with enriched instrumentation on a HST braking system configuration is separately conducted. A comparison between numerical and experimental results is carried out to validate the complete approach. Finally, based on the good results provided by the model, an optimization on the brake pas design is proposed, which allows a better distribution of the thermo-mechanical sollicitations and wear reduction.