ABSTRACT
The material properties of the annulus used in current poroelastic finite element models of the motion segment differ considerably from recent tissue level experiments. We have developed unique experiments to determine the axial tension-compression response of the annulus during finite deformation at varied strain rates, and to measure both the fluid pressure and solid stress in the center of the annulus. The axial tension-compression response, as well as the fluid and solid stresses, were highly nonlinear and significantly affected by strain rate in compression. A porohyperelastic finite element model of the annulus was then developed and validated using this experimental data.
