Rubber mandrel design suitable for manufacture co-cured hat-stiffened composite panel with large curvature by auto fiber placement technique

Producing advanced composite part with complex contour and configuration by automated manufacture process is a challenging research field ever since composite materials have been widely used in aerospace industry. In this study, three potential rubber mandrel designs suitable for producing integral hat-stiffened co-curing panel with large curvature by automatic fiber placement (AFP) technique were discussed. Finite element analysis (FEA) was utilized to study the mechanical behavior of these mandrels during the AFP process. Based on the FEA result, a mandrel design with an outer rubber bladder and a corset inner rubber mandrel enhanced with a flexible steel supporter was selected out. An actual experimental part was manufactured to study the feasibility of such design. Magnetic thickness measurement, ultrasonic defect test, and cross-section examination by metallographic microscope were conducted to study the quality of the experimental part. The results revel that producing hat-stiffened co-curing large curvature panel with desirable quality could be achieved by applying the refined rubber mandrel designed in this research.