Curvature-Interference Coupling Effect on Interlaminar Stress and Delamination Tendency in Riveted CFRP Laminates

Carbon fiber-reinforced polymer (CFRP) composites are widely used in curved aerospace structures, where riveting-induced interlaminar damage is a critical concern. Most existing studies have focused on flat laminates, while the influence of structural curvature on rivet load transfer and delamination tendency remains insufficiently understood. This study develops a three-dimensional finite element model in ANSYS Workbench to investigate the curvature-interference coupling effect on CFRP/Al single-lap riveted joints. Four curvature configurations with identical arc lengths (C0, C45, C90, and C180) are established, and riveting is simulated with upsetting displacements of 1.5-3.0 mm. Results show that curvature shifts the contact pressure from an axisymmetric pattern to a localized distribution on the convex side, while the deformation mode transitions from isotropic expansion to hoop-dominated behavior. The equivalent interlaminar shear stress increases nonlinearly with curvature and displacement. At 3.0 mm, the peak stress in C180 reaches 415.9 MPa, 1.86 times that of the flat laminate. Further analysis reveals that curvature induces membrane-bending coupling, which amplifies ply deformation incompatibility and increases delamination tendency. These findings indicate that riveting parameters developed for flat laminates cannot be directly transferred to curved structures, and curvature-interference coupling should be considered in damage-tolerant design.