Effect of inlet pressure and binder on the void content of vacuum infused unidirectional GFRP composites

In the Vacuum Assisted Resin infusion (VARI) process, typically used for wind turbine blades, the resin flowrate is known to be one of the variables affecting the void content of the composite and, therefore, its quality. The present study aims to explore this relationship in the context of manufacturing preforms, which are stacks of glass fabrics adhered together with a binder material. Six infusions were performed of a unidirectional non-crimp glass fibre fabric; three of them used fabrics treated with binder material. Infusion was carried out using polyester resin at nominal inlet pressures of 283, 533, and 1013 mbar to examine the material quality over a range of flow front velocities. The slowest cases (283 mbar) produced the lowest percentage of voids. No difference was found between the reference and binder- treated cases, suggesting that the binder and pre-consolidation has no significant effect on the infusion quality through this material. The study ultimately supports a common infusion strategy of throttling the inlet to slow down flow at the beginning of the infusion as a means of quality assurance.