Modeling of in situ strength development for the thermoplastic composite tow placement process

The composite tow placement process is a non-autoclave consolidation method that involves in situ consolidation and bonding of thermoplastic tape on a preconsolidated substrate. It can be used as a method for manufacturing large composite structures with a high degree of process control and dimensional accuracy. The bond strength that develops between layers within the laminate ultimately governs the final strength of the part. In this work, a model is presented for predicting through-thickness heat transfer and bond strength development based on intimate contact and healing at the ply interface. Experiments are carried out to validate these results for a wide variety of process conditions, and they show that model based predictive control can be used as a method for process optimization. The numerical results show that bond strength development is significantly affected by the process set points (e.g., head velocity heat input and roller pressures), and that the resulting strength can vary significantly within the part based on these set points.