The mechanical efficiency of natural materials

TLDR

Natural materials such as cellulose, lignin, keratin, chitin, collagen, hydroxyapatite, and their structures (bamboo, wood, antler, bone) exhibit a wide range of mechanical properties that can be compared using material property charts and indices to identify extreme values and evolutionary adaptations for specific loading modes. The paper aims to revise and update Ashby et al.'s natural material property charts and demonstrate their application to analyze mechanical efficiency in nature. The authors updated the existing charts by incorporating new data and refining indices, producing an improved set of charts for natural materials. The revised charts enable the study of mechanical efficiency in natural materials, as demonstrated by illustrative examples.

Abstract

The materials of nature, for example cellulose, lignin, keratin, chitin, collagen and hydroxyapatite, and the structures made from them, for example bamboo, wood, antler and bone, have a remarkable range of mechanical properties. These can be compared by presenting them as material property charts, well known for the materials of engineering. Material indices (significant combinations of properties) can be plotted on to the charts, identifying materials with extreme values of an index, suggesting that they have evolved to carry particular modes of loading, or to sustain large tensile or flexural deformations, without failure. This paper describes a major revision and update of a set of property charts for natural material published some 8 years ago by Ashby et al. with examples of their use to study mechanical efficiency in nature.