Failure Analysis and Process Optimization in Hydroforming of Fiber Metal Laminates: An Experimental and Numerical Investigation

This paper explores the application of active hydroforming for Fiber Metal Laminates (FMLs) in aircraft fairing components, in response to the aerospace industry's growing demand for lightweight yet robust materials. Despite the significant potential of FMLs, their complex structure presents major challenges in forming processes. This study investigates the effects of critical parameters, including Bulging Pressure (B_P) and Blank Holder Pressure (B_HP), on FML thickness reduction, surface quality, and filling rate. Simulations were conducted using Abaqus, while Hashin's theory was applied to predict damage initiation in the fiber layers. The results revealed a significant interaction between B_P and B_HP, which must be carefully managed to avoid defects. A bulging pressure between 1.2 and 2.4 MPa produced well-formed FML parts without defects, although the deformation was insufficient to achieve full die cavity filling and shape accuracy. The minimum required liquid pressure was derived from the FML's ultimate tensile strength, thickness, and sample radius. Finally, a novel active hydroforming curve was introduced, leading to complete FML filling. This research addresses critical forming challenges and demonstrates the feasibility of transitioning from traditional aluminum or composite fairings to advanced FML components in aerospace applications, paving the way for broader adoption.