Dynamic behaviors of bio-inspired structures: Design, mechanisms, and models

Following nature's design principles, biological entities have evolved to be highly efficient and multifunctional to maximize all the available materials and structures and to survive in harsh environments. Biomaterials and biosystems can be lightweight yet impact-resistant to withstand external dynamic loadings thanks to the fascinating architectures integrating specialized design concepts (e.g., structural hierarchy, density gradience, and thin walled tubular/cellular structures). Herein, we provide an organic review on various biological systems with sophisticated architectures perfectly for impact resistance and energy absorption, including beetle, woodpecker, mantis shrimp, nacre, bone and muscle, nutshell and fruit peel, and bamboo. From a perspective of biological functions, a comprehensive understanding of the unique structure-function relations is achieved in superior impact-resistant and energy absorption capabilities. Accordingly, the dynamic behaviors of those bio-inspired structures are also carefully reviewed in terms of the delicate design concepts, underlying mechanisms, and modeling strategies. Results demonstrate that representative bio-inspired structures exhibit beyond 60 J/g for specific energy absorptions, making them serve as excellent impact protection structures for engineering applications. Discoveries, understanding, and collection of brilliant nature-designed structures can further enable possible data-driven methodologies in engineering structural design, and the development of low-cost manufacturing technologies may enable the possible engineering application of efficient bio-inspired structures.