中文摘要：

目的构建变参数非线性模型，研究人体椎间盘在循环应变状态下的应力松弛特性。方法采用变参数非线性模型结合椎间盘应力松弛和蠕变反应的实验数据，研究循环应变状态下椎间盘的应力松弛特性，比较线性与非线性模型在循环状态下椎间盘黏弹性特性的差异。结果采用变参数非线性模型得出的循环模量和松弛系数在0．01Hz循环状态下与实验模型非常接近，得出的循环模量在0．1和1Hz频率下也与实验值相近，但是得出的松弛系数在0．1和1Hz频率下失真严重。结论在压缩应变作用下椎间盘经历的是一个非线性的应力行为，非线性变参数模型更符合研究在循环应变下椎间盘应力松弛反应的需要。

英文摘要：

Objective To construct a variable-parameter nonlinear model for the research on stress relaxation properties of human intervertebral disc under the cyclic strain. Methods The variable-parameter nonlinear model combined with experimental data on stress relaxation and creep response of the intervertebral disc were used to study stress relaxation properties under the cyclic strain and compare the differences of linear and nonlinear model in viscoelastic properties of the intervertebral disc. Results The cycle modulus and relaxation coefficient ob- tained by the variable-parameter nonlinear model under the frequency 0.0l Hz were very close to the experimen- tal data, and the cyclic modulus under the frequency of 0. ! and 1 Hz was also close to the experimental data, but the relaxation coefficient obtained in 0.1 and 1 Hz had serious distortion. Conclusions The intervertebral disc ex- periences a nonlinear stress behavior under the compression strain, so the variable-parameter nonlinear model is more suitable for studying the stress relaxation response of the intervertebral disc under the cyclic strain.