Bogies of rail vehicles for passenger coaches and traction units commonly contain air spring systems as secondary spring stages. In the development and design of spring stages, it is necessary to ensure precise knowledge about the material properties and fatigue behaviour of the air spring bellows.
The aim of this work is to systematically investigate the damage mechanisms evaluated at air spring bellows on sample level and to analyse the fatigue strength of the base material under different load conditions. A validated numerical model of the component is used as basis for deriving the local stresses of the composite. A specimen geometry is developed by means of numerical analysis, which ensures the transferability of the local load states to the specimen geometry. The determination of the stresses in the small sample is carried out by a simplified numerical model. To validate the local stresses, surface strain measurements have been carried out.
The specially developed small sample is biaxially loaded and different layups are examined at varying load levels. The fatigue test results reveal that under comparable load conditions, the fibre angle exhibits a clear influence on the fatigue strength. Furthermore, the effect of the peak load at a constant base load is also remarkable based on the conducted experiments. With the help of the presented methodology utilizing the developed representative small sample and testing procedure, a time- and cost-efficient fatigue design of cord rubber composite materials in air spring bellows of rail vehicles is facilitated.