Study on Roll Forming Process of Carbon Fiber Composite L-shaped Stringer

Carbon fiber-reinforced polymer (CFRP-T800/epoxy) stringers, particularly L-shaped, are widely used components in aircraft, necessitating efficient manufacturing solutions. This study addresses the fabrication challenges of L-shaped carbon fiber reinforced polymer stringers by automatic tape laying process and layer-by-layer roll forming, which is subsequently validated. The process begins with the creation of a CFRP pre-form flat blank via automatic tape laying process. A roll forming experimental platform is then set up, and a Box-Behnken design experiment is conducted to evaluate the effects of various process parameters including pre-form flat blank temperature, roll forming speed, roll forming pressure, and tension on the product quality. The roll forming of the resin-based CFRP thermoset L-shaped stringers produces components with measured outcomes of porosity, surface quality, and thickness uniformity. The experimental analysis demonstrates how these process parameters including pre-form flat blank temperature, roll forming speed, roll forming pressure, and tension influence porosity, thickness consistency, and bulging rate. Results show an optimal porosity of 0.0096%, a thickness standard deviation of 0.0212 mm, and excellent surface quality; and the order of influence weights of process parameters on rolled quality is: pre-form flat blank temperature, roll forming speed, roll forming pressure, tension; optimal conditions determined include a blank temperature of 55–60 °C, a rolling speed of 10.8 mm/s, a rolling pressure of 0.2 MPa, and a tension of 15 N.