Biomimetics
6 Feb 2025

Earwig-Inspired Self-Deploying Bistable Structures

The dermapteran hindwing is known for its bistable properties and efficient folding ration of 1:18 for the wings of Labia minor. The folding pattern can be described by a radial fan fold, two transversal folds and a longitudinal fold. The bistability results from the interplay of the geometry of the wing and the anisotropic distribution of resilin, a protein capable of storing elastic energy [1][2].

Distribution of resilin along the veins and broad vein patches in the hindwing of earwig. Image utilized with permission of the author Julia Deiters.
Distribution of resilin along the veins and broad vein patches in the hindwing of earwig. Image utilized with permission of the author Julia Deiters.
The wing is opened by shaking it or by pulling it open with the cerci, rotating the outer apical area upward and locking in the mid-wing mechanism. Energy is put in to open the wing and stored in the resilin, which can be primarily found along folding lines and joints. With the release of energy of the resilin, the wing is closed again. In both, the opening and closing of the wing, locally applied forces and torques lead to global deformation [1] [3]. The properties found in the dermapteran hindwing are of interest for the space industry, continuously aiming to reduce weight and stowing volume of deployable structures on spacecraft, by using minimal actuation and self-stabilizing mechanisms. Examples for deployable structures include solar panels or satellite drag sails. In this project, we built a computational tool on top of the open source MuJoCo library, to analyze the dynamics of the fan folding as a function of multiple design parameters, including geometry, mass, stiffness and actuation. This allows predictions on closing and opening of biomimetic deployable structures at different scales and optimize for minimal actuation and time. The models, generated for simulation, are subject to the geometric conditions for flat foldability [4]. Stiff and elastic elements are modeled on the distribution of the resilin in the wing [1] [5]. In addition to the simulation, the development of physical models for validation is intended as part of this project.

References

  1. Haas, F.; Gorb, S.; Wootton, R.J.: Elastic joints in dermapteran hind wings: materials and wing folding. In: Arthropod Structure & Development, Vol. 29 (2000), Iss. 2, pp. 137-146. https://www.sciencedirect.com/science/article/abs/pii/S1467803900000256
  2. Deiters, J.; Kowalczyk, W.; Seidl, T.: Strukturelle Stabilisierung des Dermapterenflügels. In: Kesel, A.B.; Zehren, D. (Hrsg.): Bionik: Patente aus der Natur - Tagungsbeiträge zum 7. Bionik-Kongress. Bionik-Innovations-Centrum. Gesellschaft für Technische Biologie und Bionik GTBB e.V., Hochschule Bremen, 2015, S. 187-191. https://whge.opus.hbz-nrw.de/opus45-whge/frontdoor/index/index/docId/695
  3. Kleinow, W.: Untersuchungen zum Flügelmechanismus der Dermapteren. In: Zeitschrift für Morphologie und Ökologie der Tiere 56 (1966), Heft 4, S. 363-416. https://www.jstor.org/stable/43262220
  4. Saito, K.; La Pérez-de Fuente, R.; Arimoto, K. et al.: Earwig fan designing: Biomimetic and evolutionary biology applications. In: Proceedings of the National Academy of Sciences, Vol. 117 (2020), Iss. 30, pp. 17622-17626. https://doi.org/10.1073/pnas.2005769117
  5. Deiters, J.; Kowalczyk, W.; Seidl, T.: Simultaneous optimisation of earwig hindwings for flight and folding. In: Biology Open, Vol. 5 (2016), Iss. 5, pp. 638-644. https://pmc.ncbi.nlm.nih.gov/articles/PMC4874351/
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Advanced Concepts Team