Hard biological materials and novel bio-inspired composites

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Billions of years of evolution have produced extremely efficient natural materials, which are increasingly becoming a source of inspiration for engineers. In materials science, biomimetics (the science of imitating nature) is now starting to inspire novel materials with extraordinary mechanical properties. This research focuses on the mechanical performance of hard biological tissues (seashells, teeth), and on the development of novel "bio-inspired" structures and materials. For example nacre, found inside many species of seashells, is 3000 times tougher than the fragile ceramic of which it is made (aragonite). This degree of improvement is currently not matched by man-made composite materials, but nature demonstrates that it is possible. Tooth enamel and dentin are other examples of tough materials combined to withstand intense mechanical and thermal loading over many years. The goal of this research is to understand how the microstructure of these materials controls their mechanical performance. We use experiments and computer simulations to study mechanisms at the macroscale, at the microscale and at the nanoscale (one billionth of a meter). More specifically, our investigations focus on: (i) the deformation and fracture of nacreous shells and teeth, focusing on the micromechanisms which prevent cracks from propagating; (ii) the nanoscale mechanics that control the behavior of the interfaces between the mineral inclusions; (iii) how these materials perform as structural systems (for example: enamel and dentin in tooth); and (iv) establishing design rules enabling the duplication of key mechanisms into artificial materials. In the context of long-term objectives, we will fabricate novel bio-inspired materials: large scale model materials to demonstrate key concepts, high performance composites for aerospace and armor systems, or ceramic coatings with enhanced adhesion.