Research on the mechanical behavior of GLARE laminates under combined tensile-torsion

Fiber metal laminates (FMLs) are extensively utilized as materials for fuselage skin panels in aircraft. Throughout the service life of an aircraft, these fuselage panels endure a range of complex loads, including tensile, bending, and torsional forces. The deformation and damage resulting from these complex loads lead to intricate failure mechanisms. To understand the damage and failure patterns of FMLs under such conditions, this study aims to investigate the mechanical behavior of glass fiber reinforced aluminum laminates (GLARE) under combined tensile-torsion (CTT) loads. The findings reveal that applying pre-torsion to the material significantly reduces its tensile properties. Specifically, when the material is subjected to a pre-torsion-tension (PTO) condition with a 45° pre-torsion angle, the material’s maximum tensile load decreases by 27.7 %, tensile strength drops by 27.6 %, and tensile strain declines by 44.9 % compared to pure tension. Conversely, when the material is subjected to a pre-tension–torsion (PTE) condition with a 500 N pre-tension load, the material’s maximum torque increases by 93.4 % compared to pure torsion. Additionally, when the material is subjected to a PTE condition with a 1500 N pre-tension load, the torsional stiffness rises by 29.3 %, while the torsional angle corresponding to the maximum torque decreases by 74.5 %. To further analyze these effects, digital image correlation (DIC) was used to monitor the distribution and evolutionary trend of strain on the specimen surface under different loading conditions. Scanning electron microscopy (SEM) was used to characterize the damage patterns in the fracture region of the specimens under different conditions. This research provides insights into the reliability assessment and structural optimization design of GLARE laminates, contributing to the advancement of materials used in aerospace applications.