F. Bumbieler

Failure Mechanisms of TGV Brake Discs

The CRISFIS project (supported by ADEME agency) consists in jointly studying the squealing and cracking aspects of the high power disc brakes for TGV very high speed trains. This paper deals with the progress concerning the cracking part. An experimental and modelling strategy is adopted in order to better understand and predict brake disc cracking. Braking tests conducted on an industrial scale-one test bench are presented. In a first step, the influence of the pad-type on the thermal loading applied to the disc is studied by means of an infrared camera and thermocouples embedded in the pads and in the disc. In a second step, the thermal maps extracted from thermographic monitoring are used as input data for thermal-mechanical calculations. Finally, the results of modelling and tests are compared to the damage observed on the brake discs.

Prediction of Crack Growth Under Random Load in Railway Wheel

Three aspects are indispensable to master railway systems: design, manufacture and maintenance. Maintenance should define surveillance intervals which are defined at present by experience. The aim of the French Railway Agency (SNCF) is to use fracture mechanic in order to satisfy to European interoperability imperative of railway stock. One study here crack growth in wheel disk under biaxial random load. An example of radial disk stress is shown in Figure 1; one can see the random aspect of the load even during straight line. Classic crack growth models are not able to predict propagation under this complex load.