Effect of stacking sequence on the mechanical behaviour of CARALL and GLARE fiber metal laminates

The present study systematically evaluates and compares the mechanical performance of CARALL_5 fiber metal laminates (FMLs) and GLARE_5 FMLs with two distinct stacking sequences. The mechanical performance was assessed considering the tensile strength, flexural strength, and impact strength of the two FMLs. Under tensile loading conditions, type-2 CARALL_5 FML exhibited a tensile strength of 776 ± 73 MPa, against a tensile strength of 466 ± 39 MPa exhibited by GLARE_5 FML. In comparison, type-1 CARALL FML, with aluminum as the outermost layers exhibited a comparatively lower tensile strength of 610 ± 53 MPa, while exhibiting a stepped failure pattern during tensile loading, indicating gradual progression of damage, and enhanced damage tolerance. The FMLs displayed failure modes such plastic deformation, fiber breakage, matrix cracking, and delamination under tensile loading conditions. The maximum values of flexural strength of around 1092 ± 85 MPa was observed in type-2 CARALL_5 FML, where the carbon fiber layers were on the outermost layers. In comparison, type-2 GLARE_5 FML displayed a 48% flexural strength, due to the lower elastic modulus and stiffness displayed by the glass fibers. Furthermore, type-1 CARALL_5 FML showed an impact energy of 14.2 ± 0.59 J, which was 98% greater than the impact energy of type-1 GLARE_5 FML. The observed failure modes were plastic deformation, fiber-matrix debonding, matrix cracking, and delamination. Based on these findings, type-1 CARALL_5 FMLs are ideal for applications involving tensile and impact loads, where it is crucial to retain load-bearing capacity even after sustaining damage. In contrast, type-2 CARALL_5 FML is more appropriate where the ability to endure bi-axial loading is essential.