Atomistic Studies of Flaw Tolerant Nanoscale Structural Links in Biological Materials
This paper discusses fundamental design concepts of nanoscale structural links in biological materials and focuses on verification of these concepts via atomistic simulations. Bone-like biological materials have achieved superior mechanical properties through hierarchical composite structures of mineral and protein, with the most basic structural units designed at a characteristic nanoscale. Gecko and many insects have developed hierarchical surface structures to achieve extraordinary adhesion capabilities through evolution, with basic structural units also at nanoscale. We argue that choosing a characteristic nanometer scale for the structural links in these materials plays a critical role in allowing the biological systems to achieve their superior properties. In both systems, restricting the characteristic dimension of the basic structure components to nanometer scale prevents crack-like flaws from propagating to break the desired structural link. We demonstrate via atomistic simulations the principle of flaw tolerance by size reduction which may have had a governing influence on the evolution of the bulk nanostructure of bonelike materials and the surface nanostructure of gecko. The present study is part of an on-going effort in our research group on learning how nature designs materials and structures at nanoscale. Biology is nanotechnology by nature, and nanomechanics plays a key role in understanding the basic engineering principles used in nature.
Key wordsFlaw-tolerance structural link continuum atomistic fracture adhesion
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