Analysis of transport phenomena governing interfacial bonding and void dynamics during thermoplastic tow-placement

The thermoplastic automated low-placement process offers the potential for cost-effective fabrication of composite parts via consolidation in situ, thus avoiding the costly autoclave consolidation. The degree of interfacial bonding between tow layers and the void content in the composite laminate directly affect the mechanical properties and performance of the products. Theoretical models for the physical phenomena governing interfacial bonding and void dynamics (growth and consolidation) during the process are presented, which constitute the core of a numerical process simulator. Simulation-based parametric studies are reported for the case of an AS-4/PEEK composite to illustrate the effects of several process conditions and placement head configurations on the resulting degree of bonding and final void content. The analysis provides valuable insight towards optimal process and placement head design.