Stress and displacement around a crack in layered network systems mimicking nacre.

Nacre is a natural composite material which has been studied because of its remarkable structure and its strength. In this paper, we revisit a layered model of nacre proposed previously [K. Okumura and P. G. de Gennes, Eur. Phys. J. E 4, 121 (2001)] in order to understand the physical reasons for the toughening via numerical simulation. We construct a two-dimensional lattice model which reflects the layered structure and perform a numerical study. This grid model reproduces the essential features predicted by the analytical solutions to the previous model and the results elucidate the reasons why the tip-stress concentration is reduced and tip displacement is enhanced in the layered system.