A research group led by Assistant Professor Kazuya Saito of the Institute of Industrial Science, the University of Tokyo has elucidated the ingenious deformation mechanism of ladybugs folding the back spring.It is expected to be applied to various products.
Ladybugs are beetles with excellent flight ability, and can instantly deploy a rear spring (rear wing: one pair behind one of two pairs of splashes) to take off.This high-speed deployment uses the restoring force of the splash to open, but the conventional explanation of the folding method was ambiguous.When folded, the first closed pod spring (the elytron: the hard front splash with polka dots) was in the way and the storage process could not be observed.
Therefore, this time, a transparent artificial pod spring made of photo-curing resin used for nail art was transplanted to Ladybugs.From a video shot with a high-speed camera, a ladybugs dexterously uses the curved surface and edges inside the pod spring and the crescent-shaped wing vein (the skeleton that supports the hind wing) to introduce a polygonal line into the splash and rub it up with the back. It became clear that it was gradually pulling in the splash.
Furthermore, when the three-dimensional shape of the splash when unfolding and storing was analyzed with a micro CT scanner, it was found that the "tape spring structure" used for tape measures was used.This structure stabilizes in the stretched state and exhibits sufficient strength, and can be elastically bent and folded at any place as needed.
The back spring of the ladybugs is a perfect combination of "flying" and "folding" functions, taking advantage of the partial flexibility of the frame.By learning from this, it is expected that it can be applied to the design and manufacturing process of various products with changing shapes, from the development of large antennas for artificial satellites to daily necessities such as umbrellas and folding fans.
