Modeling forces generated within rigid liquid composite molding tools. Part A: Experimental study

The term liquid composite molding (LCM) encompasses a growing list of processes, including resin transfer molding (RTM), injection/compression molding (I/CM), and resin infusion (a.k.a. VARTM). All LCM techniques involve compressive deformation of the fiber reinforcement prior to, and in many cases during mold filling. Forces acting on molds are primarily due to the requirement to compact the reinforcement, and pressure generated due to resin flow through these fibrous structures. An experimental study of the forces exerted on a mold during the RTM and I/CM processes is presented here. Two reinforcing materials have been considered, exhibiting significantly different resistance to compaction. The evolution of mold clamping force has been shown to be strongly influenced by the complex, non-elastic compaction behaviour of fiber reinforcements. The important effects include stress relaxation, an apparent lubrication by the injected fluid, and permanent deformation. Efforts to simulate the experiments will be presented in Part B of this study.