This work evaluates tooling-reduced ribbing by printing thermoplastic stiffeners onto thermoset composite skins via co-cured, directly printable thermoplastic interphases. A helicopter door demonstrator provides the application context for localized reinforcement features in regions where sheet moulding compound (SMC) processing is constrained by limited material flow and tooling-driven draft angles. Two material routes were investigated on M18/1 CFRP coupons as repeatable screening platforms. PEI served as a high-temperature reference interphase for printing PEI and PPSU, while PC was evaluated as a lower-temperature interphase for printing PETG. Differential scanning calorimetry was used to define substrate temperature levels, and single-lap shear tests provided first-order indicators of interface quality and process sensitivity. The results reveal a coupled thermal process window: insufficient activation leads to weak bonding, whereas excessive thermal exposure reduces lap-shear strength despite successful deposition. An analytical model further quantifies the lightweight potential of eliminating demoulding draft angles, demonstrating double-digit cross-sectional mass savings for typical rib geometries.     «

This work evaluates tooling-reduced ribbing by printing thermoplastic stiffeners onto thermoset composite skins via co-cured, directly printable thermoplastic interphases. A helicopter door demonstrator provides the application context for localized reinforcement features in regions where sheet moulding compound (SMC) processing is constrained by limited material flow and tooling-driven draft angles. Two material routes were investigated on M18/1 CFRP coupons as repeatable screening platforms. P...     »