Experiment and analysis on the aragonite layer of clam's shell

Abstract

Molluscan shell is strong, stiff, tough and shows a erose fracture surface when it is broken. In this paper, the SEM observation on a clam's shell shows that the shell is composed of aragonite layers and organic matrix. Each aragonite layer is parallel to the surface of the shell and consists of many thin aragonite sheets. These aragonite sheets are perpendicular to the layer where they are located. The observation also shows that the direction of the sheets in different layer is various and a kind of herringbone arrangement is found. The maximum pullout force of the herringbone arrangement is analyzed based on its representative model, and it shows that the herringbone arrangement can markedly increase the pullout force of the arrangement and improve the fracture toughness of the shell.