Composite materials are often joined together by adhesive bonding. However, the problem is the unreliability of adhesive joints, which means they can suddenly fracture. Due to this, adhesive joints are often overdesigned, but the problem can be partially solved by using hybrid joints. This means that the adhesive joint is reinforced with mechanical fasteners, which serve as a safety element and carry a part of the load. In our research, we have created and tested different combinations of adhesive and hybrid single lap joints with adherends of aluminium 2017-T4 and carbon fiber reinforced composite. Our research shows that the adhesive joint with two composite adherends can carry approximately 2-times greater load if the adherends have been cured together with the adhesive, compared to the adherends and the adhesive being cured separately. Our research also shows that the combination of adherends has an effect on joint strength, namely composite-aluminium can carry a ~21 % greater load, while composite-composite a ~50 % greater load in comparison to the adhesive joint aluminium-aluminium. We have not found any improvement by using composite pins made out of carbon fiber, and only a small improvement of the maximal load that the hybrid joint can take by using a pin made out of aramid fibers in comparison to adhesive joint. However, both types of pins have kept the joined parts together even after adhesive failed, resulting in higher joint strain.
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