Experimental investigation of moisture absorption and mechanical properties of GFRP laminates for stay vane extensions

This paper presents an experimental investigation into the moisture absorption behavior and mechanical properties of glass fiber-reinforced polymer (GFRP) laminates used in stay vane extensions for hydraulic turbines. The research addresses critical challenges posed by prolonged water exposure, focusing on two types of resins—Araldite RenInfusion 8601/Ren 8602 (epoxy) and Derakane 411-350 (vinylester)—and two types of fiberglass weaves—Non-Crimp Fabrics (NCF) and Satin. Laminates were subjected to accelerated aging at 40°C and natural aging at room temperature to simulate long-term water immersion. The study reveals that epoxy-based laminates exhibit higher moisture absorption rates and more pronounced mechanical degradation compared to vinylester-based laminates, primarily due to differences in resin susceptibility to hydrolysis and matrix plasticization. These findings underscore the importance of resin choice and moisture management in optimizing the durability and mechanical performance of GFRP laminates, providing valuable insights for improving composite materials in underwater applications within hydropower systems.