Amir Hajiloo, Wenfang Xie, Suong V. Hoa, Salman Khan
September 7, 2013
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 AFP 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 nonconsistent heating of pre-impregnated tow. Advanced control systems are used to control the key processing parameters of the nip point temperature of the heating system. In this study, two advanced control systems are designed by using the dynamic thermal model of the fiber placement process. One is linear quadratic regulator controller, which is implemented to achieve optimal results for quality performance. The other is model predictive controller, which is proved more efficient as the physical capacity, safety, and performance constraints of the heating system are explicitly addressed in the controller design. Polyether ether ketone reinforced with carbon fiber (APC-2) is used as the tow material in this study. The results of this study are presented including a comparison of the performance of the two control strategies through simulation study.