EFFECTS OF COMPACTION ON THE STIFFNESS AND STRENGTH OF PLAIN WEAVE FABRIC RTM COMPOSITES

Changes in fiber architecture which result from the compaction of fabr ic plies can be a major cause for scatter and inconsistencies in measu red mechanical properties. The need to quantify and provide insight in to the influence of compaction on both the stiffness and strength of p lain weave fabric composites, has led to the development of a model. T he proposed model extends an existing modelling technique, a point-wis e lamination approach using Classical Laminate Theory, to analyse the compaction problem. The analysis, which is valid for crimp angles less than 20 degrees, is applied in both the warp and weft directions, wit h ply nesting being ignored at this point in time. In this paper, the formulation of the proposed model is presented. Numerical results gene rated from the model are compared with experimental data and other ana lytical methods, in order to validate the model. A discussion on the f indings 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 compa ction. The model was found to easily model fabrics of varying fiber ar chitecture, making it a useful tool in providing insight and quantific ation on the effects on stiffness and strength caused by fiber archite cture changes resulting from compaction.