Yang Jing, Yu Lingtao, Wang Lan, Wang Wenjie, Cui Jianwei
College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin, China.
Proc Inst Mech Eng H. 2018 Jun;232(6):573-587. doi: 10.1177/0954411918774377. Epub 2018 May 11.
In traditional unconfined compression tests, the friction between platform and specimen is often considered negligible or minimized by lubrication or other means. However, friction can affect the estimation of material parameters. The percentage difference in radial deformation was investigated in this study. A novel friction estimation method was established and verified using a finite element method. The proposed method was based on the radial deformation during the compression process. Three different hyperelastic material parameters of liver tissue were applied in the simulations. The hyperelastic parameters H1 were obtained by no-slip compression tests, while the others were extracted from the literature. The results showed that the percentage difference in radial deformation was mainly influenced by the friction coefficient and diameter-to-height ( d/ h) ratio of the specimen in unconfined compression tests. The percentage difference increased as the friction coefficient and d/ h increased. Different d/ h and friction coefficient values were tested to validate the proposed method, and the accuracy was estimated to exceed 86%. An optimization strategy for material parameters in unconfined compression tests was proposed accordingly.
在传统的无侧限压缩试验中，平台与试样之间的摩擦力通常被认为可忽略不计，或通过润滑或其他方式将其降至最低。然而，摩擦力会影响材料参数的估算。本研究对径向变形的百分比差异进行了调查。建立了一种新颖的摩擦力估算方法，并使用有限元方法进行了验证。所提出的方法基于压缩过程中的径向变形。在模拟中应用了肝脏组织的三种不同超弹性材料参数。超弹性参数H1通过无滑动压缩试验获得，而其他参数则从文献中提取。结果表明，在无侧限压缩试验中，径向变形的百分比差异主要受试样的摩擦系数和直径与高度（d/h）比的影响。随着摩擦系数和d/h的增加，百分比差异增大。测试了不同的d/h和摩擦系数值以验证所提出的方法，估计其精度超过86%。据此提出了无侧限压缩试验中材料参数的优化策略。
