Flow Behavior in the Resin Infusion of Glass Fiber Reinforced Polymer Wind Turbine Blade

Abstract

This paper presents the monitoring of resin flow during resin infusion process in the fabrication of glass fiber reinforced polymer GRP wind turbine blade (WTB). Epoxy type of resin was used as the matrix and its viscosity and gel time were determined in-house. Next, resin infusions were done to obtain the permeability of the glass fiber in different directions (longitudinal and transverse), given the specific number of layers. The fabrication of composite WTB by resin infusion was conducted with the introduction of 'moldless' setup, where both upper and lower skins are covered by flexible mould/vacuum bag without any rigid female mould. However, a wooden core is used and acts as an “inner” mould to obtain the wind turbine shape. The whole infusion process was video recorded and the flow front pattern was traced at certain time intervals to investigate the infused percentage area over time. Afterward, guided by the traces of flow patterns on grid and video observation, 3D models of resin infused at interval times are generated in a CAD software. From the models, the area infused was determined. Percentage of area infused over time was compared with the analytical plot based on Darcy's law. A good agreement was found between the experimental observation and the theoretical plot.