Effects of Compaction on the Stiffness and Strength of Plain Weave Fabric RTM Composites

Abstract

Changes in fiber architecture which result from the compaction of fabric plies can be a major cause for scatter and inconsistencies in measured mechanical properties. The need to quantify and provide insight into the influence of compaction on both the stiffness and strength of plain weave fabric composites, has led to the development of a model. The proposed model extends an existing modelling technique, a point-wise lamination approach using Classical Laminate Theory, to analyse the compaction problem. The analysis, which is valid for crimp angles less than 20°, is applied in both the warp and weft directions, with ply nesting being ignored at this point in time. In this paper, the formulation of the proposed model is presented. Numerical results generated from the model are compared with experimental data and other analytical methods, in order to validate the model. A discussion on the findings from the analysis are also given, with particular focus on the initial failure mode and stress/strain distributions predicted by the model for a longitudinal tensile load case at various levels of compaction. The model was found to easily model fabrics of varying fiber architecture, making it a useful tool in providing insight and quantification on the effects on stiffness and strength caused by fiber architecture changes resulting from compaction.