Carbon composites based on multiaxial multiply stitched preforms. Part 1. Geometry of the preform

Experimental investigation of the internal geometry of a multiaxial multiply carbon reinforcement, stitched by warp-knitting, reveals the general features of this promising class of textile reinforcements. The uniform placement of the fibres is disturbed by the stitching, which creates resin-rich zones in the composite. The shape of the stitching loops, change of the stitching yarn thickness along the loop and statistical characteristics of spacing of the stitching has been studied. These features are covered by a descriptive empirical model of the internal geometry of multiaxial multiply fabrics. The model is implemented in the textile modelling software WiseTex, which serves as a preprocessor for meso-mechanics and permeability modelling.