Abstract

The effect of existing cure cycles and processes on the quality of thermoset composite parts with angle-bend is presented. A 2-D finite difference scheme was developed to model the processing of arbitrary shaped composite parts. The formulation includes heat transfer, viscosity, extent of cure, and resin flow submodels. Matrix material properties were allowed to vary with temperature. As a result, various cure parameters such as temperature, degree of cure, viscosity, compaction and fiber volume fraction were examined. A first set of experiments was done to investigate the effect of different curing cycles on temperature exotherms, thickness variation and fiber volume fraction distribution. Results from both simulation and experiment agree well. They also showed that parts produced using recommended curing cycles from manufacturers were not of good quality in terms of uniform fiber volume fraction and thickness over the cross-section of the part. Based on these results, an optimal curing process was obtained. An optimal curing process is defined as one which will produce uniform thickness and fiber volume fraction throughout the composite part including straight sections and curved sections. This process was applied to curved laminates consisting of 50 layers graphite/epoxy Hercules AS4/3501-6. Results obtained from simulation and experiment were compared. Good parts were obtained.