Fatigue behaviour of composite–composite joints reinforced with cold metal transfer welded pins

• The fatigue behaviour of composite–composite joints is investigated.
• Cold metal transfer (CMT) welded pins are used as z-reinforcement.
• DIC is applied online for evaluation of the fatigue behaviour.
• Titanium z-pinned SLS are compared to CMT pinned and co-cured samples.
• Pin reinforcement leads to increased fatigue life.

In this paper the fatigue properties of through-the-thickness reinforced joints are studied in detail. Unreinforced specimens, specimens reinforced with cold metal transfer welded titanium and steel pins and specimens reinforced with titanium z-pins are investigated. Besides classical S–N diagrams, hysteresis curves and stiffness based approaches are applied to improve the understanding of the mechanical behaviour of the joints in the progress of their fatigue life. Furthermore full field strain analysis gives information about damage initiation and growth in the joint section.