Mechanical behavior of mother-of-pearl and pearl with flat and spherical laminations

Laminated structure reduces the common inverse relationship of strength and toughness in many biological materials. Here the mechanical behavior of pearl and nacre with spherical and flat laminations was investigated and compared with the geological aragonite counterpart. The biological ceramics demonstrate higher strength, better reliability, and improved damage resistance owing to their laminated arrangement. Kinking and delamination occur in pearl to resist damage in addition to the crack-tip shielding mechanisms as in nacre, such as crack deflection, bridging, and platelet pull-out. The fracture mechanisms were interpreted in terms of the stress state using finite element simulation. This study may help clarify the compressive mechanics of laminated sphere between platens and advance the understanding on the mechanical behavior of biological and bio-inspired laminated materials. [Display omitted] •Nacre and pearl consist of aragonite and possess flat and spherical laminations.•Nacre and pearl display higher strength and reliability than geological aragonite.•Splitting is resisted by crack deflection, bridging, and platelet pull-out.•Delamination and kinking occur in pearl owing to its spherical laminations.•Kinking is caused by shear stress and favors enhanced damage tolerance in pearl.