On the vein-stiffening membrane structure of a dragonfly hind wing

Aiming at exploring the excellent structural performance of the vein-stiffening membrane structure of dragonfly hind wings,we analyzed two planar computational models and three 3D computational models with cambered corrugation based on the finite element method.It is shown that the vein size in different zones is proportional to the magnitude of the vein internal force when the wing structure is subjected to uniform out-of-plane transverse loading.The membrane contributes little to the flexural stiffness of the planar wing models,while exerting an immense impact upon the stiffness of the 3D wing models with cambered corrugation.If a lumped mass of 10% of the wing is fixed on the leading edge close to the wing tip,the wing fundamental fre-quency decreases by 10.7%～13.2%;if a lumped mass is connected to the wing via multiple springs,the wing fundamental fre-quency decreases by 16.0%～18.0%.Such decrease in fundamental frequency explains the special function of the wing pterostigma in alleviating the wing quivering effect.These particular features of dragonfly wings can be mimicked in the design of new-style reticulately stiffening thin-walled roof systems and flapping wings in novel intelligent aerial vehicles.