Fiber metal laminates (FMLs) sandwich panels are typically installed using mechanical joints. This investigation aims to enhance the bearing behavior of pin joints made of aluminum 1050–E glass FMLs. A novel core modification was achieved using a functionally graded material (FGM) technique. The impact of inserting aluminum layers at the mid-thickness of the specimens and stacking sequences of the composite core (Al/(0o/90o/0o)s/Al and Al/(90o/0o/90o)s/Al) on joint performance was also examined across different ratios of joint geometries. Furthermore, composite-like and sandwich-like layups were also compared. All tests were conducted in accordance with ASTM D5931/5961 M-17. The results indicated that the sandwich-like layup slightly enhanced the bearing strength of these joints, ranging from 1.37% to 6.16% depending on the joint geometry. Notably, inserting the mid-aluminum layer increased joint bearing strength by 11.18% by constraining delamination within the composite core. Using an FGM technique can increase the bearing strength of pin joints in FMLs by up to 27%. Furthermore, visual examination indicated that the 0° layers exhibited shear-out, while the 90° layers failed in net tension. The SEM images show fiber breakage, fiber-matrix debonding, matrix crack, delamination between the 0° and 90° composite layers, and delamination between the composite and metal layers.
ElBarrawy et al. (Mon,) studied this question.