Simulation and Measurement of Reinforcement Deformation during Preform Manufacture

The use of liquid moulding processes including resin transfer moulding (RTM) and structural reaction injection moulding (SRIM) is now becoming increasingly popular in the automotive industry. These processes involve the injection of liquid resin into a fibre preform, which may be comprised of several layers of reinforcement mats or fabrics. Structurally demanding applications usually rely on “zero-crimp” engineered fabrics consisting of two or more groups of fibres stitched together using embroidery techniques. Preform manufacture usually involves a matched mould forming process, in which layers of reinforcement are formed between rigid tools to the component geometry. This requires a degree of fibre movement and re-orientation which can have a significant effect on the resulting processing and mechanical properties. This paper describes the development of a kinematic deformation model to predict the distribution of fibres within the preform. An automatic strain measurement system is used to characterise fabric deformation, enabling the fibre orientations within three-dimensional preforms to be determined. This is applied to a number of generic geometries with increasing depth of draw, allowing the deformation characteristics of reinforcement fabrics to be established and testing the validity of the process model.