Pressure-controlled compaction characterization of fiber preforms suitable for viscoelastic modeling in the vacuum infusion process

Abstract

A woven fabric's compaction in the vacuum infusion process is characterized by applying an initial settling under a minor load, compaction, settling under a major load, decompaction and relaxation. The effects of compaction rate, relaxation pressure, wetting and debulking cycles are all investigated. Although wetting helps by increasing fiber volume fraction insignificantly, its contribution is more significant during debulking cycles by increasing the fiber volume fraction to 57.4% as compared to 55.4% for the debulked dry specimens. Recovery during decompaction is much less than the deformation during compaction, and thinning/thickening of the specimens with time under constant pressure, so called settling/relaxation pressures, indicates that fabric specimens are not elastic materials, but viscoelastic. The experimental data of this study will be valuable to compare different viscoelastic and elastic compaction models in our next study.