On the flexural response of nanoparticle-reinforced adhesively bonded joints mating 3D-Fiber Metal Laminates - A coupled numerical and experimental investigation

A coupled experimental/numerical investigation is conducted to characterize the performance of adhesively bonded joints (ABJs) mating three-dimensional fiber-metal laminates (3D-FML) subjected to tensile and flexural loading conditions. The 3D-FML consists of a 3D fiberglass fabric (3DFGF)-epoxy composite sandwiched in be-tween thin layers of Magnesium (Mg) alloys. First, the behaviour of 3D-FML single-lap bonded joints is explored and compared against single-lap joints fabricated with equivalent 2D-FML adherends made of Mg and basalt-epoxy (MB-FML). Subsequently, the effects of different concentrations of graphene nanoplatelets in the adhe-sive on the joint performance are examined. A 3D-Finite element model (FEM) is developed to investigate the damage initiation and growth in the bond-line and interface layers of the joints. The model accounts for the material and geometrical nonlinearities and incorporates a mixed-mode cohesive zone model (CZM). Finally, the field emission scanning electron microscopy (FESEM) technique is employed to analyze the distribution and agglomeration of GNPs in the adhesive. It is found that the 3D-FML joints provide higher normalized joint and energy absorption capacities compared to their equivalent mated 2D-FML counterparts. Moreover, the 3D-FML joint with 0.5 wt.% GNP-reinforced adhesive performs most optimally, providing 27% and 63% enhancements in its shear and flexural joint capacities, respectively.