A Study of Internal Defects in Flexible Medium Hydroforming of Complex Structures of Fiber Metal Laminates

A flexible medium hydroforming and curing (FMHC) process for fiber metal laminates (FMLs) was proposed and utilized to manufacture FMLs parts with complex structures. The formation mechanisms of wrinkling defects in the FMHC process of complex FMLs structure were studied through both numerical simulation and experimental methods. The results show that the compressive stress will occur at the T-shaped cavity when forming complex FMLs parts by FMHC process, which will cause wrinkling defects. To further eliminate the wrinkling, the steel-plate assisted flexible medium hydroforming and curing (SPAFMHC) process was proposed and validated. Industrial CT scanning technology was used to further analyze the distribution of internal defects in the FMLs parts formed by SPAFMHC. The results show that the defects are mainly concentrated in the corner of the ∞-shaped cavity, and the internal defects of the FMLs parts account for 4.7% of the total area of the part; The defects position was cut and observed. It is found that internal porosity and delamination are the main forms of internal defects.