DIRECT DIGITAL MANUFACTURE OF CONTINUOUS FIBER REINFORCED THERMOPLASTIC COMPOSITES INCORPORATING REDUCED TOOLING REQUIREMENTS AND PRODUCT QUALITY FEEDBACK CONTROL

The development of automated placement and in-situ consolidation of high-volume fraction continuous fiber reinforced thermoplastic composites, using commingled tow feedstocks, offers a path to the manufacture of complex structural products with radically reduced tooling requirements. Reduced tooling needs can enable more rapid introduction of design alternatives. However, manufacturing process parameters are commonly determined by trial and error, resulting in a “best” processing schedule, in the hope that consistent, high-quality composites are produced. This approach to process parameter development for evolving part geometries can also reduce productivity. Equipment and manufacturing technologies will be discussed that allow structural composite products, including grid stiffened panels to be produced without the complex tooling usually employed to produce grid stiffeners and manage material build-up at stiffener intersections by consolidation force feedback control. In addition, preliminary results are presented demonstrating that tow width can be employed as a direct metric of composite grid stiffener quality and can be used in the real-time control of the automation system, with the goal of removing the need to follow a single, predetermined processing schedule. Thus, the combination of the automated positioning with in-situ consolidation and the implementation of a composite quality-based real-time feedback control approach, holds the potential to continuously tune the process parameters, representing an important step toward a future alternative to conventional composites processing.