Table 2.

Material properties of the finite element model [18].

	Cortical bone	Cancellous bone	Endplate	Endplate cartilage	Nucleus pulposus	Annulus fibrosis	Cartilage
Element type	Shell	Hexahedron	Shell	Shell	Hexahedron	Hexahedron	Shell
Material model	Power-law plasticity	Power-law plasticity	Power-law plasticity	Isotropic elastic	Viscoelastic	Isotropic elastic	Isotropic elastic
Material properties	ρ = 1.83 g/cm3 E = 16700 MPa v = 0.3 k = 440.8 MPa n = 0.2772	ρ = 1.0 g/cm3 E = 291 MPa v = 0.3 k = 7.118 MPa n = 0.2741	ρ = 1.83 g/cm3 E = 5567 MPa v = 0.3 k = 146.9 MPa n = 0.2772	ρ = 1.68 g/cm3 E = 25 MPa v = 0.4	K = 2.2 GPa Gs = 2 MPa Gl = 1.4 MPa	ρ = 1.2 g/cm3 E = 3.4 MPa v = 0.49	ρ = 1.68 g/cm3 E = 10 MPa v = 0.4

ρ indicates the density. E indicates the Young modulus. v indicates the Poisson ratio. k indicates the strength coefficient. n indicates the strain hardening exponent. K indicates the volume model. Gs indicates the short-time shear modulus. Gl indicates the long-time (infinite) shear modulus.