Buckling-induced sound production in the aeroelastic tymbals of Yponomeuta

The loss of elastic stability (buckling) can lead to catastrophic failure in the context of traditional engineering structures. Conversely, in nature, buckling often serves a desirable function, such as in the prey-trapping mechanism of the Venus fly trap ( ). This paper investigates the buckling-en...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2024-02, Vol.121 (7), p.e2313549121
Main Authors: Mendoza Nava, Hernaldo, Holderied, Marc W, Pirrera, Alberto, Groh, Rainer M J
Format: Article
Language:English
Subjects:
Acoustics
Actuation
Aeroelastic stability
Aeroelasticity
Animals
Buckling
Camber
Catastrophic events
Context
Directivity
Elastic buckling
Mechanical properties
Morphing
Moths
Physical Sciences
Plants (botany)
Predators
Prey
Resonant frequencies
Robotics
Signal strength
Sound
Sound pressure
Sound production
Ultrasonics
Wing camber
Wings
Yponomeutidae
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Summary:The loss of elastic stability (buckling) can lead to catastrophic failure in the context of traditional engineering structures. Conversely, in nature, buckling often serves a desirable function, such as in the prey-trapping mechanism of the Venus fly trap ( ). This paper investigates the buckling-enabled sound production in the wingbeat-powered (aeroelastic) tymbals of moths. The hindwings of possess a striated band of ridges that snap through sequentially during the up- and downstroke of the wingbeat cycle-a process reminiscent of cellular buckling in compressed slender shells. As a result, bursts of ultrasonic clicks are produced that deter predators (i.e. bats). Using various biological and mechanical characterization techniques, we show that wing camber changes during the wingbeat cycle act as the single actuation mechanism that causes buckling to propagate sequentially through each stria on the tymbal. The snap-through of each stria excites a bald patch of the wing's membrane, thereby amplifying sound pressure levels and radiating sound at the resonant frequencies of the patch. In addition, the interaction of phased tymbal clicks from the two wings enhances the directivity of the acoustic signal strength, suggesting an improvement in acoustic protection. These findings unveil the acousto-mechanics of tymbals and uncover their buckling-driven evolutionary origin. We anticipate that through bioinspiration, aeroelastic tymbals will encourage novel developments in the context of multi-stable morphing structures, acoustic structural monitoring, and soft robotics.
ISSN:0027-8424
1091-6490
1091-6490
DOI:10.1073/pnas.2313549121