A systematic investigation was carried out in this work to evaluate the effect of seawater ageing on the mechanical properties of different composites manufactured with three types of unidirectional carbon fibres, based on a novel powder epoxy system. The flexural behaviour of the samples with and without accelerated seawater ageing was evaluated. A significant strength reduction due to seawater ageing was observed in the composites. Changes within the materials are also evaluated by interlaminar fracture toughness testing and dynamic mechanical thermal analysis. Interlaminar fracture toughness mode-I testing using the Double Cantilever Beam (DCB) test, revealed that the interfacial adhesion differences in combination with the moisture uptake could alter the fracture resistance of the composites, hence emphasising the importance of the interfacial bonding strength. A Finite Element analysis was carried out to gain insight on the important modelling parameters, for mode I dominated failure, and compared with the experimental results. Fracture surface examination by scanning electron microscopy revealed delamination, fibre debonding/bridging and plasticising of resin due to seawater effect.

在这项工作中进行了一项系统研究，以评估海水老化对三种单向碳纤维制造的不同复合材料机械性能的影响，该复合材料基于一种新型粉末环氧树脂系统。评估了有和没有加速海水老化的样品的弯曲行为。在复合材料中观察到由于海水老化导致的强度显着降低。材料内部的变化也通过层间断裂韧性测试和动态机械热分析进行评估。使用双悬臂梁 (DCB) 测试的层间断裂韧性模式 I 测试表明，界面粘附差异与吸湿率相结合可能会改变复合材料的抗断裂性，因此强调了界面结合强度的重要性。进行了有限元分析以深入了解重要的建模参数，对于模式 I 主导的故障，并与实验结果进行比较。通过扫描电子显微镜检查断口表面发现由于海水效应导致树脂的分层、纤维脱粘/桥接和塑化。