Thermal Control System Design for Automated Fiber Placement Process

One of the important concerns about the quality of the thermoplastic composite in Automated Fiber Placement (AFP) process is the degradation of thermoplastic resin, resulting from the overheating or the lack of proper heating by the heating system used in the automated fiber placement machine head. Heat transfer between the heating system and incoming pre-impregnated tow is not easy to control and can result in energy loss or non consistent heating of pre-impregnated tow. The advanced control systems are used to control the key processing parameter of Nip Point Temperature of the Heating System. Two advanced control systems are designed by using the dynamic thermal model of the fiber placement process. One is Linear Quadratic Gaussian (LQG) controller which is implemented to achieve the optimal results for quality performance. The other is Model Predictive Controller (MPC) which is proved more efficient as the physical capacity, safety and performance constraints of the heating system are explicitly addressed in the design of the Model Predictive Controller (MPC). Poly-ether-ether-ketone (PEEK) reinforced with carbon fiber (APC-2) is used as the focused material. The performance of the two control strategies are compared and illustrated through simulations.