Journal of Materials Research

Rapid Communications

Platelet interlocks are the key to toughness and strength in nacre

Kalpana S. Kattia1 c1, Dinesh R. Kattia1, Shashindra M. Pradhana1 and Arundhati Bhoslea1

a1 Department of Civil Engineering, North Dakota State University, Fargo, North Dakota 58105


Nacre, the inner layer of mollusk shells is a composite made of platelets of mineral aragonitic calcium carbonate with a few weight percent organic material sandwiched in between. The organic and nanostructural nuances are often suggested to be the reason for the extreme toughness of nacre. Here we report the presence of interlocks between platelets of nacre from red abalone. We also report and show, using three-dimensional finite element modeling, that interlocks are the key mechanism for the high toughness and strength of nacre. The observed rotation between platelet layers, which were earlier reported as defects of structure, are necessary for the formation of interlocks.

(Received July 15 2004)

(Accepted February 24 2005)

Key Words:

  • Biological;
  • Biomimetic;
  • Mechanical properties


c1 Address all correspondence to this author. e-mail: