Predicting Stress Distribution Exerted on LCM Tools during Filling Phases

SUMMARY: Mould tools used for LCM processes such as Resin Transfer Moulding (RTM) and Injection/Compression Moulding (I/CM) must withstand local forces due to resin pressure and compaction of the fibre reinforcement. Prediction of these tooling forces will allow cost effective mould design and process selection. A series of RTM and I/CM experiments have been undertaken, monitoring total clamping force and normal stress distribution acting on mould surfaces. A mixed elastic and a visco-elastic reinforcement compaction model have been used to model these processes, both being compared to experimental data. Both models show good agreement to experiment during compaction phases, however the visco-elastic model matches the experimental data significantly better during periods influenced by stress relaxation. Circumferentially averaged stress distributions are also compared at key points in the process, both models showing good qualitative agreement to experiment, and the RTM cases also matching well quantitatively. Overall, the RTM process has been modeled accurately, while some discrepancy exists for I/CM during secondary compaction, when fluid is compressed along with reinforcement.