A Compaction Model for Liquid Composite Moulding Fibrous Materials

Abstract

Liquid Composite Moulding (LCM) processes are a family of advanced composite materials manufacturing processes, which includes the Resin Transfer Moulding (RTM), Injection/Compression Moulding (I/CM) and Vacuum Assisted Resin Infusion (VARI) processes. In an LCM process, many important manufacturing parameters depend on the stresses taken up by the fibrous material before, during and after the fluid-filling stage. For example, the tooling forces in an RTM process and the fill-time and part-thickness in a VARI process depend on this fibre stress. Fibrous materials respond to load in a complex manner, exhibiting viscoelastic effects and undergoing permanent deformation. A new framework for the mathematical modeling of these materials is proposed based on thermomechanical arguments. Physical phenomena of the microscale such as fibre bending, fibre-to-fibre friction and the concept of “frozen energy” are incorporated. The framework is demonstrated for the case of a fibrous material undergoing permanent deformations during a compaction/unloading cycle and the results are compared with experiment.