Transverse compaction of 2D glass woven fabrics based on material twins - Part I: Geometric analysis

In Liquid Composite Molding (LCM), compaction of the reinforcement occurs during several stages of the entire process, including before and during resin injection, which leads to significant deformation of the fibrous architecture. This affects not only the manufacturing process, but also the mechanical properties of final parts. This article aims to study by X-ray microtomography the mesoscopic deformations of 2D glass woven fabrics under transverse compaction for a range of fiber volume fractions encountered in high performance composite applications. The analysis is based on the recently proposed Micro-CT Aided Geometric Modeling (AGM) technique Huang et al. (2019) [1], which is used to create, from the three-dimensional images of dry textile preforms obtained by microtomography, "material twin" geometric models representative of fiber architecture. Three "material twin" mesostructural geometric models of a stack of multiple layer 2D woven fabrics are generated from microtomographic images at different compaction levels. Since all the fiber tows are reconstructed from real fabrics and are labeled separately, the deformation and displacement of fiber tows during compaction can be subsequently studied, which is not necessarily possible with other reconstruction methods. The results show that contacts between fiber tows have an effect on the evolution of their morphological features, which is related to the material variability of fiber tows in real fabrics. Tracking of the fiber tows positions also reveals that the vertical displacement of fiber tows are significant, while their horizontal movements are negligible.