Analysis of fiber steering effects in thermoplastic automated fiber placement

This paper investigates aspects of non-geodesic layup in Thermoplastic Automated Fiber Placement (TAFP). To study possible effects on process and layup quality, coupon laminates with curved fiber paths at variable radii were manufactured. Process parameters were varied systematically. The temperatures at the nip point were recorded with an infrared camera system and matched with the robot position data. The resulting temperature plots were used to analyze the temperature distribution, yielding particularities of steering layup regarding energy absorption behavior. Further, an optical sensor was used to record a raw image of the fiber angle distribution. A MATLAB routine was developed for detecting undulations, which were characterized in terms of wavelength. The routine was validated by microscopic analysis, and subsequently applied to analyze the fiber undulation distribution over a tow width. Finally, the trajectory radius and process parameters were correlated to the resulting undulations on tape level.