Modeling of heat transfer and void dynamics for the thermoplastic composite tow-placement process

Thermoplastic composite tow-placement technology is a nonautoclave consolidation process that offers the potential to significantly reduce fabrication costs by using in situ consolidation as a method for manufacturing large composite components. The temperature history and resulting degree of consolidation directly control the final part quality and are directly affected by the process set points. In this work, series of integrated submodels are developed for predicting the heat transfer and void dynamics within the laminate. The final through thickness void fraction is predicted as a function of process parameters. Experiments are carried out to validate these results for a wide variety of process conditions. The model is used to quantify the relationships between variation of quality of incoming material (e.g., void content ranges 3.1 and 5.5% and final void content gradients. It was found that significant gradients in final void content exist through the thickness and is directly related to processing conditions. Recommendations for process optimization are discussed.