Hierarchical flexural strength of enamel : transition from brittle to damage-tolerant behaviour

Hard, biological materials are generally hierarchically structured from the nano- to the macroscale in a somewhat self-similar manner consisting of mineral units surrounded by a soft protein shell. Considerable efforts are underway to mimic such materials because of their structurally optimized mechanical functionality of being hard and stiff as well as damage-tolerant. However, it is unclear how different hierarchical levels interact to achieve this performance. In this study, we consider dental enamel as a representative, biological hierarchical structure and determine its flexural strength and elastic modulus at three levels of hierarchy using focused ion beam (FIB) prepared cantilevers of micrometre size. The results are compared and analysed using a theoretical model proposed by Jäger and Fratzl and developed by Gao and co-workers. Both properties decrease with increasing hierarchical dimension along with a switch in mechanical behaviour from linear-elastic to elastic-inelastic. We found Gao's model matched the results very well. This journal is © 2011 The Royal Society.

Subjects

Biological materials

Dental enamel

Hierarchical structures

Mechanical properties

DDC Class

610: Medizin

Funding(s)

Untersuchung des Deformations- und Bruchverhaltens der hierarchischen Ebenen von Zahnschmelz

More Funding Information

Forschungs- und Wissenschaftsstiftung Hamburg

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Hierarchical flexural strength of enamel : transition from brittle to damage-tolerant behaviour