Quantitative evaluation of toughening mechanisms in abalone nacre

Tensile and fracture tests for dried nacre were carried out. Dried nacre fractured in a brittle fashion, but its toughness perpendicular to the plane of the plate was 10 times greater than that of natural CaCO3. A simple model in which plates interlock was proposed based on the observations of fracture behavior and the fractured surface. The contribution of interlocking to toughness was estimated; it was confirmed that the interlocking of the plates is the main factor in the toughening of dried nacre.