Prediction and experimental verification of normal stress distributions on mould tools during Liquid Composite Moulding

Abstract

Moulds for Liquid Composite Moulding (LCM) processes such as Resin Transfer Moulding and Compression RTM must withstand significant forces generated by resin injection and preform compaction. Prediction of tooling forces will allow optimisation of setup costs and time, and optimal selection of peripheral equipment (such as presses). A generic LCM simulation (SimLCM) is being developed with the capability to predict clamping forces and stress distributions acting on mould tools. Both mixed-elastic and viscoelastic reinforcement compaction models are implemented within SimLCM. A series of novel rigid tool LCM experiments were undertaken using a flat plate part geometry, and are compared to results generated by SimLCM. In general, predictions are very good, with the viscoelastic model providing significant improvement over the mixed-elastic model during phases involving stress relaxation within the reinforcement. Novel aspects of this work include measurement and prediction of spatial normal stress distributions and time dependent stress relaxation behaviour of reinforcements.