A Novel Forming Limit Characterization Method and Failure Analysis for Uncured Al/ <scp>GFRP</scp> Laminates: Numerical and Experimental Investigations

ABSTRACT Fiber metal laminates (FMLs) are regarded as a novel type of hybrid composite material. However, due to the alternating stacking of metal and fiber layers, the formability of FMLs is primarily influenced by the fibers and the interfacial bonding performance. Moreover, fibers cannot undergo significant deformation between layers in traditional forming limit characterization methods and are prone to premature failure, resulting in low measurement accuracy and stability. In this study, focusing on low‐constraint fiber deformation, a novel forming limit characterization method is proposed to systematically investigate the effects of fiber weaving modes, resin viscosity, and resin impregnated area on the formability of aluminum/glass fiber reinforced plastic (Al/GFRP) laminates under various strain paths. The results showed that twill fibers, having fewer interlacing points and better drapability than plain fibers, increased the forming limit by 6.2%. The forming limit was significantly influenced by resin viscosity, with improvements of 8.5%, 10.9%, and 14.2% recorded for the three viscosities tested. Additionally, a larger resin impregnated area more effectively enhanced formability, achieving forming limit increases of 5.1%, 8.5%, and 9.2% at 20%, 50%, and 100% impregnation areas. This study brings new insights into exploring the forming limit behavior and failure mechanisms of FMLs.