Comparison of four hyperelastic models for intervertebral discs: A finite element study

Intervertebral disc (IVD) is a highly special soft tissue that resides between two neighboring vertebrae in the spinal column, and is responsible for load-bearing and mobility in the spine. Deformability of spine is mostly because of the presence of this structure, and thus obtaining precise mechanical behaviour of it is of great importance. In many studies, intervertebral disc samples were subjected to various tests in order to discover their mechanical models. In this study, a segmental model of spine was developed, and based on existing data in the literature resulted from various tests, four conventional hyper-elastic models, i.e. Neo-Hookean, Mooney-Rivlin I, Mooney-Rivlin II, and Yeoh, were assigned to the annulus in the FE model. The model was subjected to the same boundary conditions as those of the experiments, i.e. four degrees of lateral bending and flexion/extension. All the mentioned models showed acceptable results that were in agreement with experimental data (R-square> 0.95). However, Yeoh s model acquired the highest R-square, i.e. 0.998, and thus it was selected as the most suitable model for the IVD. The coefficients that were calculated with the curve fitting process on the experimental data were compared under physiological loading conditions.

کلیدواژه ها:

Intervertebral disc ، Finite Element Method ، Non-linear behavior ، Hyper-elastic models ، Spinal column.