On the void reduction mechanisms in vibration assisted consolidation of fibre reinforced polymer composites

Vibration- and vacuum-assisted curing experiments of laminate composites were carried out using a method involving a flat curing chamber and heat transfer fluid. The laminates were made with woven glass fabric and epoxy resin systems, and were subjected to void content analysis. Of the wide range of frequencies studied (0–8 kHz), the low frequency vibrations (around 10 Hz) resulted in significant void content reduction (by approximately 60%) compared to curing without vibration assistance. Analysis of solubility, diffusion and dynamic effects leads to a hypothesis for the possible mechanisms of void reduction, which include bubble growth and escape by reduction of pressure (vacuum), dissolution and growth by the Thomson–Freundlich effect, and enhancement of the diffusion and growth process due to vibrations amplified by damped natural resonance frequency.