Stable, durable and amazingly break-proof: what lies behind the amazing features of the insect’s wings can be transferred to technology, researchers report. They show how the combination of flexible joints, mechanical stoppers and “kink areas” make insect wings efficient and shockproof. By recreating these elements that they transferred to 3D printed airplane models, they were able to illustrate the efficiency of the concept. The three-component system could thus open up new possibilities in the development of technical systems, say the researchers.
Dragonflies, bees and the like whiz through the air with astonishingly powerful “lightweight construction technology”: Their wings usually make up just two percent of the total mass of the insects, and yet the filigree structures are difficult to withstand: In addition to the considerable aerodynamic loads, they can also withstand heavy loads Bumps stood. They survive frequent collisions with obstacles such as flowers, leaves or branches without major damage. So far, human technology has hardly been able to guarantee such performance combinations in connection with high endurance. But how can they bring out the insect’s wings? The working group “Functional Morphology and Biomechanics” at the Christian-Albrechts-Universität zu Kiel deals with this question. The focus is on the comparatively large wings of the dragonflies.
As the scientists explain, technical constructions can usually only efficiently guarantee one property: Either they can withstand large loads, such as stable load-bearing components in buildings, or, thanks to their flexibility, they are particularly resistant to breakage in the event of collisions. If both features could be combined better, more efficient technical structures could be developed that can adapt their malleability to the respective requirements. However, previous approaches to this are often complicated and costly and are therefore hardly suitable for widespread use, say the scientists.
Refined biomechanics
“What is still preoccupying engineering research is something that insects have long perfected,” says co-author Stanislav Gorb. In the current study, he and his colleagues now show the peculiarities in the wing structure of the insects on which the interesting combination of characteristics is based. As they report, three elements in the wing structure and their combination form the basis for this: flexible joints, mechanical stoppers and “kink areas”. “Thanks to this special structure, the insect wings can adopt different degrees of flexibility, depending on what the respective situation requires,” says Gorb.
As the researchers explain, insect wings consist of veins with a membrane stretched between them. Micro-joints connect the individual wires and enable the wings to bend under low load. These elements also ensure that the structure can withstand long-term loads, the researchers explain. However, when the load is greater, the movement is then stopped by microscopic spikes that sit on the micro-joints. These “stoppers” support the wings against heavy loads, the researchers explain. Number three of the structural elements then form special areas in the wing that occur during the collisions
come into play with obstacles: Due to their high deformability, they enable non-destructive, reversible buckling, which prevents the structures from breaking. “Thanks to these three elements, insects are able to adapt their wing properties and thus fulfill several functions at the same time,” explains first author Ali Khaheshi.
Transfer the concept to model aircraft
As part of their study, the researchers artificially simulated these biomechanical elements and were able to illustrate their efficiency and technical potential. They transferred the elements to about eight centimeters in size and 3.8 grams in weight aircraft models, which they produced using 3D printing. The process made it possible to equip the wings with functional replicas of the micro-joints, stoppers and kink areas of the insect wings (see illustration). The researchers then subjected these models and controls without the elements to various stress experiments. They also let the models hit obstacles and hit the ground.
It was shown that the wings with the biologically inspired elements survived the collisions, while conventionally constructed aircraft models broke. In addition, the scientists tested various modified constructions in which they omitted one of the three construction elements. “These experiments confirm that all three elements are necessary together to ensure the combination of features,” reports Khaheshi.
As the scientists point out, the convertibility of the biological concept into a technical one now illustrates the potential for the development of applications. The particularly interesting aspect of the biologically inspired system is that the strategy is based on structural elements in the wings that function autonomously – without the need for additional energy. “Such findings from biology could help us to construct technical systems that adapt independently to extreme or unforeseen situations – for example in environments in which humans cannot actively intervene, such as space missions,” says co-author Hamed Rajabi in conclusion.
Source: Christian-Albrechts-Universität zu Kiel, specialist article: Adv. Sci., Doi: 10.1002 / advs.202004338