Numerical Study of Shark Tessellated Cartilage in Bending

ChEMS Seminar

Featuring: Xiaoxi Liu

PhD Candidate

Chemical Engineering & Materials Science

Universityof California, Irvine

Much of the skeleton of sharks, skate and rays (Elasmobranchii) is characterized by a tessellated structure,

composed of a shell of small, mineralized plates (tesserae) joined by intertesseral ligaments overlaying a soft

cartilage core.  The significance of this skeletal tissue type — particularly from a mechanical

perspective — is unknown.  A cross-sectional model, based on empirical material property and morphological

data, was developed in the present work to analyze the function of intertesseral joints in regulating the stress

distribution within the skeletal tissue during bending.  The results indicate that this structure distributes

more stress to the tesserae loaded in compression when compared to those loaded in tension.  This behavior

provides plausible advantages for 1) reducing susceptibility to fatigue damage; 2) reducing tearing of the tissue

by large tensile stresses and 3) allowing compressive stress to power nutrient flow throughout the unmineralized

phase.  The present model simulations demonstrate these advantages for a typical geometry and range of ligament properties.

Biography:

Xiaoxi Liu completed a B.S. degree in materials science and engineering at South China University of Technology. He started to pursue his Ph.D degree in chemical engineering and materials science at the University of California, Irvine, in 2007. His dissertation work is to investigate mechanical properties of shark skeletons using analytical models, dynamic mechanical tests and microscopy techniques under the supervision of Prof. James C. Earthman.