Optimized structures for vibration attenuation and sound control in Nature: a review

TL;DR

This review explores how natural hierarchical structures optimize dynamic mechanical properties like vibration damping and sound control, highlighting bioinspired strategies for developing advanced materials.

Contribution

It synthesizes current knowledge on natural hierarchical structures for dynamic properties and discusses their potential in bioinspired phononic and metamaterial applications.

Findings

Natural structures exhibit multi-scale hierarchies for dynamic property optimization

Bioinspired designs can enhance vibration and sound control technologies

Limited research exists on hierarchical influence on dynamic properties

Abstract

Nature has engineered complex designs to achieve advanced properties and functionalities through evolution, over millions of years. Many organisms have adapted to their living environment producing extremely efficient materials and structures exhibiting optimized mechanical, thermal, optical properties, which current technology is often unable to reproduce. These properties are often achieved using hierarchical structures spanning macro, meso, micro and nanoscales, widely observed in many natural materials like wood, bone, spider silk and sponges. Thus far, bioinspired approaches have been successful in identifying optimized structures in terms of quasi-static mechanical properties, such as strength, toughness, adhesion, but comparatively little work has been done as far as dynamic ones are concerned (e.g. vibration damping, noise insulation, sound amplification, etc.). In particular, relatively limited knowledge currently exists on how hierarchical structure can play a role in the optimization of natural structures, although concurrent length scales no doubt allow to address multiple frequency ranges. Here, we review the main work that has been done in the field of structural optimization for dynamic mechanical properties, highlighting some common traits and strategies in different biological systems. We also discuss the relevance to bioinspired materials, in particular in the field of phononic crystals and metamaterials, and the potential of exploiting natural designs for technological applications.