Studying the influence of different carbon-fibre-reinforced polymer patches on the mechanical properties of carbon-fibre-reinforced polymer composite

Joining textile layers to a preform using patches is of utter importance in regards to producing structural elements made of fibre-reinforced materials with complex geometry, and repairing fibre-reinforced composites in an efficient and safe manner. Material-efficient and load-specific design and integration of the patch are essential in relation to the performance of the joint as well as the strengthening of the composite structure after a damaging event. Hence, in this study, the stress–strain behaviour of carbon-fibre-reinforced epoxy-composites, which are joined by a patch designed as double-lap joint, will be investigated. It will be shown that the woven fabric morphology (surface structure) and the woven fabric construction (weave pattern) of the join partners exert a noticeable influence on the stability of the patched composite samples. The use of leno non-crimp fabrics as patch structures, which provide an increased joint surface in comparison to the likewise examined twill fabrics, enables a growth in joint strength, provided that the dimensions of the patch remain the same.