Hyperelastic Constitutive Model for Sheep Intervertebral Disc

The intervertebral disc (IVD) plays an important role in the normal functioning of the spine and acts as an interface to hold the vertebra together. IVDs have been subjected to different tests to find out their mechanical models. Different species of animal models are used for in vivo and in vitro for spinal column researches. Many studies have found similarities between sheep and human spines in terms of anatomy and geometry. The study of biomechanical similarities is essential for the improvement of diseases and surgical techniques. Obtaining precise mechanical behavior of IVDs is great importance for researching. In this study we try to investigate the hyperelastic behavior of sheep intervertebral disc and also find the appropriate mathematical model for describing of that. In order to do this, after isolating intervertebral disc from sheep uniaxial compression tests with constant strain rate carried out and the achieved data were used to fitted by three conventional hyper-elastic models, i.e. Moony-Rivlin, Neo-Hookean and Yeoh to report the best hyperelastic model for IVD.