A novel high-performance bio-inspired double-blade composite stiffened structure (Bio-DCSS) inspired by avian wing bone

While bio-inspired design has significantly advanced the performance of composite laminates and T-joints, its application to stiffened structures remains underdeveloped. To address this gap, this study proposes a novel bio-inspired double-blade composite stiffened structure (Bio-DCSS), emulating the "dense outer and sparse inner" architecture of avian wing bones to mitigate stress concentration at web-flange junctions. A high-fidelity progressive damage model (PDM), integrating a strain-based 3D-Hashin failure criterion, continuum damage mechanics (CDM), and a cohesive zone model (CZM), was developed and validated against experimental data. The results demonstrate that, with a mere 2.09% mass penalty, the Bio-DCSS achieves remarkable improvements over its conventional counterpart: 39.74% in buckling load, 11.50% in ultimate load, 2.94% in pre-buckling stiffness, and 12.45% in post-buckling stiffness. Parametric studies further reveal that the load-bearing capacity is highly sensitive to the position of the Polyvinyl Chloride (PVC) foam. This work provides not only a high-performance bio-inspired solution but also a validated modeling methodology and design insights for the lightweight design of next-generation aerospace structures.