【摘要】 目的针对当前摩擦力对脂肪组织无约束压缩实验结果影响的不确定性,研究压缩实验中合适的摩擦系数设置及适用于模拟脂肪组织生物力学响应的材料本构模型。方法构建低应变率(0. 2 s-1)和中应变率(20 s-1)下的脂肪组织有限元模型,分别应用LS-DYNA中常用于模拟脂肪组织的线性黏弹性材料本构、Mooney-Rivlin超弹性材料本构、Ogden超弹性材料本构、软组织材料本构,在不同摩擦系数下进行无约束压缩实验,分析不同摩擦系数及本构模型对接触力大小的影响。结果 4种材料本构模型在低、中应变率下,输出的接触力均与摩擦系数呈正相关,有摩擦时的接触力比无摩擦时的接触力大50%左右。中应变率下脂肪组织的力学响应对摩擦系数的灵敏度比低应变率下的更高,且不同材料本构模型输出的接触力差异显著。结论在脂肪组织无约束压缩实验中,静摩擦系数取0. 1,动摩擦系数取0. 05是合理的,在低、中应变率下Ogden超弹性材料本构能够良好地反映脂肪组织的生物力学响应。更多还原

【Abstract】 Objective In view of the uncertainty of the effect of friction on the experimental results of unconstrained compression of adipose tissue,the appropriate friction coefficient setting in compression experiments and the material constitutive model for simulating the biomechanical response of adipose tissue are studied. Methods The finite element( FE) models of adipose tissue used for low strain rate( 0. 2 s-1) and medium strain rate( 20 s-1) were developed. The unconstrained compression tests of adipose tissue under different friction coefficient were simulated by LS-DYNA code using the developed FE models with different constitutive models,such as linear viscoelastic material constitutive model of adipose tissue,the Mooney-Rivlin hyperelastic material constitutive model,Ogden hyperelastic constitutive materials,soft tissue material constitutive model. The influence of different friction coefficients and constitutive models on the contact force was analyzed. Results Under the low and medium strain rate,the contact force with four kinds of material constitutive models obtained from the simulations was positively correlated with the friction coefficient,and the contact force with friction was more than 50% higher than that without friction. The mechanical response of adipose tissue under medium strain rate was more sensitive to friction coefficient than that under low strain rate. Furthermore,the contact force of the constitutive models of different materials was significantly different. Conclusions For the unconstrained compression test of adipose tissue,the static friction coefficient of 0. 1 and the kinetic friction coefficient of 0. 05 are reasonable in the simulation. Under low and medium strain rate,Ogden hyperelastic constitutive models can well reflect the biomechanical response of adipose tissue.更多还原