Comparative structural analysis of anterior and posterior wings of the dragonfly

Abstract

Dragonflies are insects fitted with two pairs of wings: a narrower pair located on the front side and a wider pair located behind. The geometry of these wings has been studied by other authors, but differences between these are visible, showing structural differences designed by nature. The aim of this paper was to compare the structural behaviour (stress and strain) of both pairs of dragonfly wings. The wings were simulated as grids supported in the animal body, according to natural geometry. The results show that the wings are composed of elements from 3 to 7 faces, and although similar to each other, there are some differences in structure and geometry between them: (i) the posterior wings support greater load because they have larger area (x2.4); (ii) the number of main structures connecting with the body in both is eight; (iii) the main connections in the anterior wings are closer, favouring the direction of flight; (iv) the posterior wings are set closer to the center of gravity of the insect, which causes the body weight to be supported by these wings, the anterior wings getting to the manoeuvres of flight; (v) analysis shows that the anterior wings support more concentrated efforts, while the posterior wings, due to their larger area, have reduced stress; (vi) the same is said of deformations, where the anterior wings deform more than the posterior wings (x2.4). Nature designed dragonfly wings with different geometry and function, in which the anterior wings are responsible for handling the flight, and the posterior wings are responsible for sustaining the animal's body. The ratio between the number of frames and the number of joints is equal to the number of gold (1.618).