Vacuum-Assisted Resin Infusion Molding (VARIM) Processing for Thick-Section Composite Laminates in Wind Turbine Blades

摘要

In this paper a comprehensive investigation of exothermal reaction and curing kinetics is conducted on thick glass-fiber reinforced thermoset composite laminates up to 80 plies (3.6 inches after cure) in thickness. The composite material selected for the study is a polyester-matrix-based, E-glass fabric reinforced composite system of various laminate thicknesses. Composite laminate panels of 8-inch by 8-inch in size have been infused in a setup representative of large-part VARIM processing. Through-thickness exothermic temperature, ion viscosity, degree of cure and their evolutions in the composite during processing are obtained by direct measurements of embedded thermocouples and dielectric sensors. Through-thickness curing index profiles at different time instances are determined from the DEA data and related to the instantaneous degree of cure to illustrate the curing extent and its variations in the thickness direction of the thick composite. Dimensional stability of the thick laminate composite is determined in real time during the infusion and curing processes. The important issue of the laminate-thickness effect on through-thickness gradients and their evolutions of exothermic reaction temperature and curing kinetics are addressed. Comparisons are made with a series of experiments on composite laminate panels with several different numbers of plies.