SEM212 Assignment 2 -A Biomimetic Study of Nacre Biomimicry is defined as the design and production of materials, structures, and systems that are modelled on biological entities and processes (Oxford University Press, 2012). Nacre is a highly fracture resistant material found in nature, particularly in a number of mollusc shells. It is commonly referred to as ‘mother of pearl’ and has an iridescent appearance. This inner shell layer protects the soft tissues of the mollusc against damaging debris. It has been a key area of research over the past decade. Nacre exhibits an unusually high fracture toughness for its high strength. Which is uncommon in nature where ductility is generally traded for strength, thus decreasing a materials fracture toughness. Therefore it is an ideal subject of design for improving fracture toughness of materials based on biomimetics. They key structural features of nacre that researchers are attempting to mimic are, its high strength and toughness, and its continued resistance to catastrophic fracture even after large amounts of splintering. It is rare for a material to exhibit a high yield strength and still remain fracture resistant, particularly in ceramics (Ashby, Shercliff, Cebon, 2010 pg. 183). In many engineering scenarios it is desirable to use a material that is both strong and tough. Nacre features a number of mechanisms that contribute to its high fracture toughness. It is primarily constructed with ceramic platelets of aragonite (CaCO3), around 95% volume, that are surrounded on all sides by a thin adhesive organic layer. The presence of this viscoelastic and resilient layer allows the transfer of energy into various modes of failure, including crack diversion, the creation of new surface area, pullout of platelets, and most significantly crack bridging (Mayer 2010, pg.8). These modes of failure, as seen in Figure 1, absorb a large amount of energy, and therefore considerably increase the energy required to propagate a crack. A…