Effect of Neighbouring Plies and 3D-Loop-Threads on the Fatigue Life of Glass Fibre Reinforced Polypropylene

AbstractUsing textile composites with straight fibre orientation in-plane, improved lightweight structures can be designed and produced, where the fibres are specifically positioned in line with the flux of force induced by external loads. Here, the structural properties are dominated by the material properties of the 0°-fibres under static as well as under fatigue loading. It is well known, the failure behaviour in fibre direction is affected by textile loop threads and adjacent plies, for example by notch effects of inter fibre cracks. For the experimental characterisation of the influence of 3D-loop threads as well as adjacent plies on the fatigue performance, the degradation behaviour of unidirectional and textile glass fibre reinforced polypropylene in tension-tension fatigue loading has been analysed. The material configurations have selectively been chosen to achieve identical fibre volume fraction of the reinforcement fibres in loading direction and therefore gain a high comparability in fatigue loading. The driving damage mechanisms are observed using imaging methods, such as light microscopy and computer tomography.The achieved experimental results will be incorporated into the failure mode dependent fatigue analysis models already been published by the authors