Little Jesse S, Khalsa Partap S
Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8181, USA.
J Biomech Eng. 2005 Feb;127(1):15-24. doi: 10.1115/1.1835348.
The human facet joint capsule is one of the structures in the lumbar spine that constrains motions of vertebrae during global spine loading (e.g., physiological flexion). Computational models of the spine have not been able to include accurate nonlinear and viscoelastic material properties, as they have not previously been measured. Capsules were tested using a uniaxial ramp-hold protocol or a haversine displacement protocol using a commercially available materials testing device. Plane strain was measured optically. Capsules were tested both parallel and perpendicular to the dominant orientation of the collagen fibers in the capsules. Viscoelastic material properties were determined. Parallel to the dominant orientation of the collagen fibers, the complex modulus of elasticity was E*=1.63MPa, with a storage modulus of E'=1.25MPa and a loss modulus of: E" =0.39MPa. The mean stress relaxation rates for static and dynamic loading were best fit with first-order polynomials: B(epsilon) = 0.1110epsilon-0.0733 and B(epsilon)= -0.1249epsilon + 0.0190, respectively. Perpendicular to the collagen fiber orientation, the viscous and elastic secant moduli were 1.81 and 1.00 MPa, respectively. The mean stress relaxation rate for static loading was best fit with a first-order polynomial: B (epsilon) = -0.04epsilon - 0.06. Capsule strength parallel and perpendicular to collagen fiber orientation was 1.90 and 0.95 MPa, respectively, and extensibility was 0.65 and 0.60, respectively. Poisson's ratio parallel and perpendicular to fiber orientation was 0.299 and 0.488, respectively. The elasticity moduli were nonlinear and anisotropic, and capsule strength was larger aligned parallel to the collagen fibers. The phase lag between stress and strain increased with haversine frequency, but the storage modulus remained large relative to the complex modulus. The stress relaxation rate was strain dependent parallel to the collagen fibers, but was strain independent perpendicularly.
人体小关节囊是腰椎结构之一，在脊柱整体负荷（如生理屈曲）过程中限制椎体运动。脊柱的计算模型无法纳入准确的非线性和粘弹性材料特性，因为此前尚未对其进行测量。使用市售材料测试装置，采用单轴斜坡-保持方案或正弦位移方案对小关节囊进行测试。通过光学方法测量平面应变。在平行和垂直于小关节囊中胶原纤维主导方向的情况下对小关节囊进行测试。测定了粘弹性材料特性。平行于胶原纤维主导方向时，复合弹性模量E* = 1.63MPa，储能模量E' = 1.25MPa，损耗模量E" = 0.39MPa。静态和动态加载的平均应力松弛率与一阶多项式拟合效果最佳：分别为B(ε) = 0.1110ε - 0.0733和B(ε) = -0.1249ε + 0.0190。垂直于胶原纤维方向时，粘性和弹性割线模量分别为1.�1和1.00MPa。静态加载的平均应力松弛率与一阶多项式拟合效果最佳：B(ε) = -0.04ε - 0.06。平行和垂直于胶原纤维方向的小关节囊强度分别为1.90和0.95MPa，伸长率分别为0.65和0.60。平行和垂直于纤维方向的泊松比分别为0.299和0.488。弹性模量是非线性且各向异性的，小关节囊强度在平行于胶原纤维方向时更大。应力与应变之间的相位滞后随正弦频率增加，但储能模量相对于复合模量仍然较大。应力松弛率在平行于胶原纤维方向时与应变有关，但在垂直方向时与应变无关。
