Durability study of adhesive joints used in high-speed crafts manufactured with composite materials subjected to impact fatigue

Abstract

Marine high-speed crafts manufactured with composite materials are exposed to constant impacts due to the cyclic contact of the vessel with the water surface. These low-energy impacts can affect the structural integrity of the hull and could be an example of impact fatigue. Certain fast boats manufactured with composite materials are designed in such a way that the hull and deck are assembled with adhesive joints. However, in most of these cases, the adhesive thickness is not measured or controlled. The purpose of this research is to evaluate the effects of the adhesive thickness on the durability and crack growth rate behaviour of adhesive joints used in certain types of high-speed crafts under constant amplitude fatigue and impact fatigue regimes. This study was performed by using experimental procedures with double cantilever beams and single lap joints specimens. The results showed that the durability at impact fatigue conditions is two orders of magnitude lower than constant amplitude fatigue at comparable force levels. In addition, the crack growth rate in impact fatigue conditions showed improvement of fatigue properties when a lower thickness of adhesive was used. On the other hand, the crack growth rate was lower in the constant amplitude fatigue regime in comparison to impact fatigue.