Investigation on the tensile properties of stitched perforated-metal-core carbon fiber-reinforced composites

Carbon fiber-reinforced polymer (CFRP) composites are widely employed in the aerospace industry. In this study, a novel stitched perforated-metal-core (SPMC) specimen is fabricated, and its tensile failure mechanism is systematically elucidated. The results indicate that resin shrinkage, plate-induced stress concentration, and fiber pull-out govern the surface roughness of SPMC. Failure features combine metal plastic deformation and composite fiber pull-out. The stitching yarns enhance the structural rigidity of SPMC in the early stage, but later become a source of stress concentration, accelerating the metal’s degradation. The modulus of SPMC is significantly higher than that of baseline composites, yet heterogeneous deformation mismatch induces stress drops. The SPMC tensile failure occurs in three distinct stages: the approximate linear elastic deformation, the steady-state damage accumulation, and the metal plastic failure stage. This study provides theoretical insights and technical references for the design optimization of metal-composite hybrid structures, the refinement of connection configurations, and the accurate prediction of failure behavior.