Materials become insensitive to flaws at nanoscale: Lessons from nature

TLDR

Natural nanocomposites such as bone, tooth, and nacre achieve superior strength by organizing proteins and minerals at the nanometer scale, which is essential for their mechanical performance. The study investigates whether the nanometer‑scale design principles of natural nanocomposites can be applied to create laboratory nanomaterials with enhanced strength and flaw tolerance. The study demonstrates that natural nanocomposites use a generic mechanical structure where mineral particle size is tuned for optimum strength and flaw tolerance, and that stress concentration at flaws is not applicable to nanomaterial design.

Abstract

Natural materials such as bone, tooth, and nacre are nanocomposites of proteins and minerals with superior strength. Why is the nanometer scale so important to such materials? Can we learn from this to produce superior nanomaterials in the laboratory? These questions motivate the present study where we show that the nanocomposites in nature exhibit a generic mechanical structure in which the nanometer size of mineral particles is selected to ensure optimum strength and maximum tolerance of flaws (robustness). We further show that the widely used engineering concept of stress concentration at flaws is no longer valid for nanomaterial design.