A comparative study of the pin-bearing responses of two glass-based fibre metal laminates

The pin-bearing behaviour of two commercially available glass-based fibre metal laminates (FMLs), GLARE® 2 and GLARE® 3, is presented. Results shown include bearing stress, strain, stiffness and strength, surface strains in the vicinity of the hole, and damage progression using microscopy. The initial stiffness, the bearing strain at which non-linearity first occurs and the initial rate of stiffness loss were similar for both materials, indicating that the initial bearing behaviour of these FMLs is dominated by the metal layers. Microscopy results provided experimental evidence that delamination first occurs in FMLs as a result of interlaminar normal stresses from pin loading and not because of buckling of the metal layers. Final failure for both materials involved complete separation of layers caused by out of plane deformation. The ultimate bearing stress and strain were significantly higher for GLARE® 2 than for GLARE® 3, which the micrographs indicate is due to the higher bending stiffness of the reinforcing layers in GLARE® 2, which delays out of plane deformation during the final failure sequence. Measurements of surface strains showed similar initial behaviour for both materials, in agreement with the analysis of the bearing stress–strain curves, and provided additional insight into the final failure sequence of the two materials.