Analysis of the interaction of adjacent layers of a GFRP-laminate under fatigue loading

A layer-wise strength analysis of laminates leads to realistic results not only with quasistatic but also with cyclic loading. The used fatigue strength has to be determined by experiment. Degradation models exist, used to reduce the laminate stiffness due to inter-fibre fracture (IFF) cracks. However a notch effect caused by IFF – in other words, a local increase in stress in the laminate adjacent to the laminate affected by an IFF – is not included. This leads to a premature failure of the laminate much earlier as it is predicted by a failure criteria. Performing 3-point-bending tests the notch effect was measured to obtain a more exact service life prediction. Adequate crack arresting layers are tested which will reduce the negative notch effect.