Figure 1

(a) Tension test curve and direction of nacre. (b) Curve of longitudinal-transverse strains of nacre. (c) The changes of Poisson’s ratio ${\nu }_{13}$ in the deformation of nacre, where the first index stands for the direction of applied load $x_1$ and the second index stands for the direction of transverse deformation $x_3$, as shown in the inset of (a).Reuse & Permissions

Figure 2

Schematic illustrations showing the microarchitecture of nacre. (a) The average thickness of an aragonite platelet layer and an organic matrix layer are 500 and 25 nm, respectively, the average spacing of each of the aragonite platelets is about $8\mu \mathrm{m}$. An aragonite platelet of nacre is divided into two regions: The “core” is the region that is common to the platelets belonging to the same column, and the “overlap” region corresponds to the area where platelets from adjacent columns overlap. The length of overlap is about $1/3$ length of a platelet on the cross section of nacre. (b) There are a large number of mineral bridges in the organic matrix layers. The minimum and maximum parts of the diameter of the mineral bridges are about 20 and 50 nm, respectively, and the height of the mineral bridges is equal to the thickness of the organic matrix layers. In the core region, the average bridge-to-bridge spacing between the neighboring mineral bridges is about 50 nm and in the overlap region, the average bridge-to-bridge spacing between the neighboring mineral bridges is about 80 nm.Reuse & Permissions

Figure 3

Schematic illustrations showing the deformation between two neighboring mineral bridges in the overlap region of an organic matrix layer of nacre. (a) Both the mineral bridges and the organic matrix are applied to a shear stress and nacre laterally contracted in elastic. At this time, the thickness of the organic matrix and aragonite platelet is about $H_1\approx 524.79\mathrm{nm}$. (b) The neighboring mineral bridges fracture, $H_2\approx 524.79\mathrm{nm}$. (c) The rest parts of the two fractured mineral bridges intrude into the organic matrix and start to slide along the opposite direction in the organic matrix layer, $H_3\approx 524.10\mathrm{nm}$. (d) The rest parts of the two neighboring fractured mineral bridges slide to meet and begin to climb one another, $H_4\approx 524.10\mathrm{nm}$. (e) The rest parts of the two neighboring fractured mineral bridges climb one another to arrive at the tops and shear to fracture in sequence the macromolecules of the organic matrix, $H_5\approx 524.72\mathrm{nm}$.Reuse & Permissions