Fatigue behaviour of flax-basalt/epoxy hybrid composites in comparison with non-hybrid composites

Investigation on the fatigue life of hybrid composites is critical to extend their structural applications. However, there is a lack of research on fatigue performance of hybrid composites. In this study, the fatigue life of a flax-basalt woven-ply hybrid composite is investigated and compared with the behaviour of 100% flax and 100% basalt composites. After the optimisation of the epoxy resin curing cycle, tension-tension fatigue tests were performed on samples with two orientations, 0 degrees/90 degrees and +/- 45 degrees. S-N curves with absolute values and with normalised values are discussed. Results showed that the hybridisation was able to produce a positive effect on the fatigue resistance of basalt laminates: a better normalised fatigue resistance was obtained for the hybrid composite in comparison with the 100% basalt one in both orientations. A two-parameter fatigue life model was then applied and showed its ability to predict the fatigue behaviour of the hybrid composite for the two orientations. An analysis of damage mechanisms by means of infrared thermography and scanning electron microscopy allowed observing the different types of damage occurring during fatigue loading in hybrid composites.