Mechanical properties and numerical simulation of Sulcata tortoise carapace.

Abstract

Carapace of Sulcata tortoise acts as a natural shield that protects the body from natural predators. The carapace consists of four layers: keratin scutes, dorsal cortex, cancellous interior and ventral cortex. This study aims to investigate the load-bearing mechanisms of the carapace by characterizing the layers, measuring their mechanical properties and relating them to the macroscopic behavior under compression and bending loads. Test results indicate the influence of layers' morphology, especially porosity and structural compositions, on the macroscopic properties of the carapace. The bending samples are simulated using a commercial finite element code as laminate composite structures with homogeneous elastic layers. The models are shown to capture the load-displacement response of the carapace in the elasticity regime under quasi-static loadings.