Cross-Scale Biological Models of Species for Future Biomimetic Composite Design: A Review

The rise in structural performance requirements in engineering is driving the research and development of stronger, stiffer, and lighter materials. However, most traditional artificial materials are unable to meet the needs of modern industrial and technological development. In fact, multifarious creatures in nature are further ahead in their use of structural materials. There is a fairly limited selection of natural structural materials at ambient temperatures. They usually consist of hard and soft phases arranged in a complex hierarchy with characteristic dimensions ranging from nanoscale to macroscale. The resulting materials usually show a nearly perfect combination of strength and toughness integrated with lightweight characteristics. This is exactly what is required of engineering materials. In this review, different biological materials were divided into the following types in terms of structural elements: 1D fibrous structures, 2D layered structures, 3D cellular structures and heterogeneous interface structures. For each structural element, corresponding structure components and mechanical properties of typical organisms were well described. Abundant sophisticated models of natural biological structures were discussed contrastively. The purpose of this review was to summarize the excellent properties of multi-dimensional biological models with cross-scale features and to reveal the relationship between structure characteristics and function mechanism, which could provide valuable references for the design and optimization of a future biomimetic composite with high mechanical performance. This review is anticipated to not only inspire novel biomimetic design but also offer a window for the deep understanding of existing outstanding structural composites in diversified species, which could provide continuous innovative power for composite renovation in many engineering fields.