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Item type:Publication, Effect of microstructure on the mechanical and damping behaviour of dragonfly wing veins(Royal science publication, 2016-02); ; ; ; Insect wing veins are biological composites of chitin and protein arranged in a complex lamellar configuration. Although these hierarchical structures are found in many 'venous wings' of insects, very little is known about their physical and mechanical characteristics. For the first time, we carried out a systematic comparative study to gain a better understanding of the influence of microstructure on the mechanical characteristics and damping behaviour of the veins. Morphological data have been used to develop a series of three-dimensional numerical models with different material properties and geometries. Finite-element analysis has been employed to simulate the mechanical response of the models under different loading conditions. The modelling strategy used in this study enabled us to determine the effects selectively induced by resilin, friction between layers, shape of the cross section, material composition and layered structure on the stiffness and damping characteristics of wing veins. Numerical simulations suggest that although the presence of the resilin-dominated endocuticle layer results in a much higher flexibility of wing veins, the dumbbell-shaped cross section increases their bending rigidity. Our study further shows that the rubber-like cuticle, friction between layers and material gradient-based design contribute to the higher damping capacity of veins. The results of this study can serve as a reference for the design of novel bioinspired composite structures.journal articleBand:3Heft:2144 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Wound-induced reactivation of developmental cuticle programmes in mature insectsThe insect cuticle exoskeleton is among the most abundant and versatile biological structures. During ontogeny, the cuticle undergoes extensive modification, enabling insects to adapt to a wide range of ecological niches. In contrast, cuticular remodelling is generally thought to cease after adult emergence, raising the question of how mature insects respond to damage to their exoskeleton. To address this fundamental issue, we used an interdisciplinary experimental approach combining biomechanics, quantitative image analysis and molecular biology to investigate the response of mature Locusta migratoria to cuticular injury. We show that deep tibial wounds penetrating the epidermis trigger a coordinated repair programme that integrates rapid sclerotization of the perilesional cuticle with the local deposition of newly synthesized, layered cuticle beneath the wound site. These structural responses are accompanied by a strong but transient reactivation of the developmental enzyme chitin synthase 1 and the induction of the antimicrobial peptide defensin 3 in the vicinity of the injury. In contrast, superficial injuries that do not reach the epidermis fail to elicit cuticle deposition and sclerotization. Together, our results demonstrate that mature insects retain the capacity to locally reactivate developmental cuticle pathways to restore exoskeletal integrity, thereby directly linking structural repair with immune activation.journal article35