Tesserae mechanics & materials
The tessellated mineralization of shark and ray skeletons occurs near the surface, sandwiched between a fibrous outer layer (the perichondrium) and the unmineralized cartilage core of the skeleton. This arrangement appears to provide the composite structure a combination of remarkable mechanical properties, including high stiffness, flexibility and energy absorption, allowing them to resist loads but to deform and dissipate energy simultaneously. To extract the key design principles of this interesting composite material system, we use a variety of material and mechanical characterization approaches at multiple length scales, such as transmission electron microscopy, nanoindentation, and wide-field SEM imaging coupled with micromechanical testing. The design strategies discovered through this comprehensive multi-scale study will be later on incorporated into a multi-material 3D-printed physical model as well as 2D and 3D finite element models of tessellated cartilage. This approach allows us to decouple design features at different length scales, further evaluate the cause-effect relationships in a controlled manner, and finally lead to the informed fabrication of bio-inspired advanced structural composite materials.