Integral Quality Assurance Method for a CFRP Aircraft Fuselage Skin: Gap and Overlap Measurement for Thermoplastic AFP

Manufacturing carbon reinforced plastics with Automated Fiber Placement (AFP) is a widely adopted process despite inherently introduced defects of gaps and overlaps during the manufacturing process. Gaps and overlaps are usually cured during the consolidation process if limited to a certain size, otherwise they will lower mechanical properties of the component. Thus, gaps and overlaps have to be detected and measured especially in a thermoplastic process without a final consolidation step. For this purpose, a quality assurance sensor, based on laser triangulation, is integrated into a thermoplastic AFP machine mounted on a robot. For this paper the data recording and evaluation comprises a full-scale thermoplastic fuselage half shell with 8 m length and a diameter of 4 m. A Computer Vision pipeline extracts and quantifies the gap and overlap defects. The paper compares multiple visualization approaches of the results to showcase their advantages for various stages of component design and production. By illustrating the gaps and overlaps in a 3D graphic, precise localization of out of tolerance defects can be determined to adjust process parameters during production. Preconditions for simulation tools can be defined by summarizing all defects in a 2D heatmap, to improve variable stiffness properties for example.