Experimental and numerical investigations of Otala lactea's shell-I. Quasi-static analysis.

At the first glance, mollusk shells may seem complex spatial structures with interesting shapes, forms and colors. However, from an engineering point of view, they are mechanical barriers which provide remarkable protection against environmental factors. These biological composites which exhibits an attractive combination of stiffness, strength and toughness, may be mimicked in bio-inspired materials. In the present work, a mathematical method is used to develop comprehensive three-dimensional (3D) numerical models of mollusk shells. The models are employed to study the mechanical behavior of the shells under static loading conditions. Numerical analyses are conducted using ANSYS finite element (FE) codes. A combination of indentation testing and scanning electron microscopy (SEM) is utilized to confirm the validity of the models and the solving procedures. A good agreement is observed between the shape, size and location of the failure obtained from experimental tests and numerical predictions. The results indicate that the columella increases the ability of mollusk shells to withstand applied mechanical forces without failure. Further, it can be concluded that the coiling geometry of the shells adequately modifies the stress distribution and reduces the stress concentration.