Butterfly Wing Membranes' Deformation Study

Flapping-wing aircraft, owing to their high aerodynamic efficiency and exceptional maneuverability, have become a focal point in bio-inspired aerospace research, with simulation serving as a critical enabler for their engineering applications. Existing studies commonly treat the wing membrane as an idealized flexible material, neglecting the significant influence of its geometric morphology on structural stiffness, and lack quantitative mechanical analysis of the membrane formation mechanism, resulting in limited simulation accuracy. This study establishes a fluid-structure coupling analysis framework by integrating prior observational data, experimental measurements, and numerical simulations. For the first time, this work shows that localized topographical thickening is capable of raising the stiffness or natural frequency of the modeled wing membrane. Findings are qualitatively consistent with select morphological features of real butterfly wings, indicate a correlation between black-spot distribution and global stiffness, and offer insights into the mechanical construction mechanism of wing membranes together with relevant optimization analysis. This stiffness-enhancing interpretation is further supported here by biochemical, morphological and geometric evidence from the published literature-melanin-coupled cuticle sclerotization, scale micro-architecture and wing corrugation-establishing the black spot as a multi-functional, stiffness-reinforcing element. This work advances the theory of morphological-mechanical coupling in flapping-wing systems, provides foundational support for high-fidelity simulation modeling, and accelerates the engineering transition of flapping-wing aircraft.