Mechanical characterization of polymer composite materials for long length ships

In the marine industry Fibre-Reinforced Polymers (FRP) are currently dominating the manufacture of vessels up to 50m in length, with liquid resin infusion (LRI) being the most frequently used manufacturing technique, of which vacuum-assisted liquid resin infusion is the most widely adopted LRI variant. However, current regulations (SOLAS from IMO) restrict the use of composite materials in vessels over approximately 50m in length. FIBRESHIP is a Horizon 2020 funded EU project that aims to further the use of FRPs in vessels over 50m in length by addressing the regulatory restrictions and the numerous other challenges associated with manufacturing long-length FRP composite ships. The mechanical performance of new commercially available composite materials as potential candidates for selection in composite ship construction is central to this work. This paper provides an overview of selected work performed as part of the FIBRESHIP project in terms of evaluating various mechanical properties of selected laminates under dry and wet conditions. Test samples extracted from a glass fibre reinforced vinyl ester laminate were immersed in seawater at 35°C for durations of one month and three months. Three-point bend and interlaminar shear strength tests were performed to evaluate the retained flexural strength and interlaminar shear strength of the composite laminates post immersion. After three months of immersion the retained flexural strength and interlaminar shear strength was 90% and 79% respectively, highlighting the potential effect of seawater on the laminate and the importance of accounting for these effects during the design phase. Tested specimens were also examined using micro-computed tomography (μCT) to evaluate the failure morphology.