Journal of Materials Research

Articles

Mechanical properties of nacre constituents and their impact on mechanical performance

François Barthelata1, Chun-Ming Lia1, Claudia Comia1a) and Horacio D. Espinosaa1 c1

a1 Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208-3111

Abstract

The mechanical properties of nacre constituents from red abalone were investigated. Electron microscopy studies revealed that the tablets are composed of single-crystal aragonite with nanograin inclusions. Both nanoasperities and aragonite bridges are present within the interfaces between the tablets. By means of nanoindentation and axial compression tests, we identified single tablet elastic and inelastic properties. The elastic properties are very similar to those of single-crystal aragonite. However, their strength is higher than previously reported values for aragonite. A finite element model of the interface accounting for nanoasperities and the identified properties revealed that the nanoasperities are strong enough to withstand climbing and resist tablet sliding, at least over the initial stages of deformation. Furthermore, it was observed that the model over-predicts strength and under-predicts ductility. Therefore, we conclude that other interface features must be responsible for the enhanced performance of nacre over its constituents.

(Received July 18 2005)

(Accepted February 23 2006)

(Online publication August 2006)

Key Words:

  • Biological;
  • Composite;
  • Elastic properties

Correspondence:

c1 Address all correspondence to this author. e-mail: espinosa@northwestern.edu

Footnotes

a) On leave from Department of Structural Engineering, Politecnico di Milano, Milano, Italy.

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