Insect wings have been widely studied for their lightweight structure, efficient hinge mechanisms, ability to support flight, and in many insects the capacity to fold. During flight, the wings receive aerodynamical forces that lead to deformations such as bending and torsion. The flexibility of the insect wings is influenced by the material properties of the cuticular membrane, the organization of the hollow wing veins, as well as the corrugation pattern, and the overall surface area geometry of the wing. We study all of these topics, relate findings to the evolutionary patterns we see among winged insects, and also use findings as inspiration for the bioinspired design of micro aerial vehicles (MAVs).
The wing veins play an important role in allowing for deformation and optimizing flight performance. For instance, the hollow beam-like longitudinal veins in dragonfly wings are thicker than the cross veins and have a different hierarchical organization of the cuticular layers Those cuticular layers provide a stiffness gradient with generally a stiffer outer cuticle and a less stiff in the inner core. In addition, the veins located at the base and at the leading edge of the wing are thicker than those at the tip, and trailing this leads to greater stiffness in areas with thicker veins, while thinner veins provide flexibility at the tip. We study dragonfly species with different flight behaviors. Dragonflies are known for their impressive flight capabilities that are supported by their lightweight, flexible, and strong wings. Our flight test data showed that a migratory dragonfly species have distinctive flight abilities compared to non-migratory species. Migratory species also have different wing characteristics (vein distribution, wing shape, wing corrugation, wing surface microtrichia) compared to non-migratory species. We thus compare the material and mechanical characteristics between migratory and non-migratory dragonfly species.
Another important aspect that contributes to the insect’s survival is the ability to fold its wings. Grasshoppers, cicadas, and cockroaches are types of insects that possess this ability. The forewings of grasshoppers are usually shorter, smaller, and thickened compared to the hind wings. When at rest their hind wings need to be folded neatly and stored under the forewings to avoid damage to these more delicate wings and to become more compact overall. When initiating flight, grasshopper forewings will lift and quickly move forward and out of the way, and the larger hindwings will also unfold to support gliding and flight. While the hind wings must be flexible enough to be able to fold and unfold many times, it is also important that they should also be stiff and rigid to withstand aerodynamical forces during flight. In addition, since the muscles of the wing, the actuators of the unfolding and folding mechanisms, are located only at the base of the wing, folding and unfolding are controlled remotely by forces that are generated through the release of elastic energy stored in the wing material.
Even though an extensive number of research studies have been conducted on insect wing structures to understand their properties, our understanding of how the material properties of the cuticle, as well as vein and membrane hierarchal organization, affect the flexibility of the wing, and as how to fabricate a functional insect wing that can be folded, is still rudimentary. We hope to contribute to the field linking biology and engineering by focusing on the material properties, and resulting structure and form.
Project Lead
Siti Fauziyah
Collaborators
- Paul Lee – Mechanical and Aerospace Engineering – Princeton University
- Dr. Aimy Wissa – Mechanical and Aerospace Engineering – Princeton University
- Dr. Jake Socha – Department of Biomedical Engineering and Mechanics – Virginia Tech
- Dr. Jessica Ware – American Museum Natural History
Publications