Effect of interlocking structure on mechanical properties of bio-inspired nacreous composites

As a biological material, nacre has attracted more and more attention because of its remarkable mechanical properties, which were generally attributed to the staggered brick and mortar structure. Recently, topological interlocking was believed to be one of the key mechanisms for the high toughness and strength of nacre. This paper aims at evaluating the mechanical behaviors of nacreous composites with interlocking structures, by a combination of analytical solution and numerical simulation. The elastic modulus, tensile strength and toughness of the composites are obtained as functions of the geometrical parameters, which are related to the waviness of the tablet. It is found that the elastic modulus of the nacreous composites increases with the increasing of tablet waviness, and there exists a critical angle for the interlocking structure where both high strength and toughness can be achieved. Furthermore, finite element analysis (FEA) shows that the interlocking angle of the tablets plays an important role in the brittle-to-ductile transition of the composites, and good agreement is obtained between the theoretical solutions and simulations. The results can potentially provide a guideline to the design and optimization of bio-inspired composites with interlocking structures.