Steering for in-situ AFP-manufactured structures: Part 1 - Critical arc length

Automated Fiber Placement (AFP) of thermoplastic composites offers a pathway to efficient, Out-of-Autoclave (OoA) manufacturing of large aerospace structures. This work investigates the in-plane path curvature (steering) required for double-curved geometries and the following transient steering effects and defect formation. A novel “critical arc length” concept is introduced to define the limits of viable steered layup paths. Results demonstrate that sub-critical steering radii do not significantly impact interlaminar shear or bending strength, though a minor reduction in bending modulus is observed near the critical arc length, likely attributable to increased fiber waviness. These findings expand the design space for steered thermoplastic composite structures.