Effect of cure parameters on void content and mechanical properties of composite laminates

This study investigates the effects of curing parameters including pressure, heating rate, and time on mechanical performance of composite laminates, specifically focusing on interlaminar shear strength (ILSS), flexural properties, and void content. Seven cure cycles were designed and optimized by controlling the following processing parameters during autoclave manufacturing: (a) pressure (0.3, 0.5, and 0.7 MPa), (b) heating rate (0.6, 2.2, and 3.9°C/min), and (c) cure time (90, 120, and 150 min) with autoclave curing applied at 179°C. Seven composite panels were fabricated using these cure cycles to study the effects of the previously mentioned parameters on curing quality. The void content and interlaminar and flexural properties were studied using the ILSS described in EN-2563, the three-point bending method outlined in ASTM-D790, and the determination of the fiber, resin, and void contents specified in EN-2564, along with scanning electron microscopy. Consequently, the most important parameter identified for the ILSS is the void volume fraction. Moreover, void content is highly dependent on pressure throughout the cure cycle. With increased pressure from 0.3 to 0.7 MPa, the void content decreased from 0.29% to 0.12% and the ILSS increased by 10.32%. Statistical analysis was performed to determine significance and correlations.