双曲型碳纤维褶皱夹芯结构的三点弯曲损伤特性

Based on the concept of a hybrid design, a hyperbolic foldcore sandwich structure was developed by connecting the topological features of S-fold and olive-fold patterns. The failure mechanisms of this structure under three-point bending were investigated using a combined experimental and finite element approach,and the effects of core wall thickness and bending direction were studied. In addition, the bending performance of the hyperbolic foldcore structure was compared with that of a single-cell S-fold structure using finite element simulations. The results indicate that under longitudinal bending, thin-walled specimens primarily exhibit face sheet crushing and core indentation, whereas thick-walled specimens transform to top-face-sheet fracture and face-core debonding. For transverse bending, the core wall thickness has a negligible influence on the failure mode, with face-core debonding being the dominant failure mechanism. Furthermore, increasing the core wall thickness improves the bending performance of the structure and reduces the anisotropy of the bending behavior. When the core wall thickness increases from 0.4 mm to 0.8 mm, the specific bending stiffness and specific peak load of the longitudinal specimens increase by 19.2% and 41%, respectively, whereas those of the transverse specimens increase by 68.6% and 69.2%, respectively. The ratio of the bending stiffness between the longitudinal and transverse specimens decrease from 2.54 to 1.79. The hyperbolic foldcore exhibits a comparable longitudinal bending performance to the S-fold core, demonstrating a significantly higher transverse bending stiffness.