The sensitivity of nonlinear computational models of trabecular bone to tissue level constitutive model.
The sensitivity of nonlinear computational models of trabecular bone to tissue level constitutive model.
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DOI：
10.1080/10255842.2015.1041022
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发表时间：
2016
影响因子：
1.6
通讯作者：
Niebur GL
中科院分区：
文献类型：
--
作者：
Baumann AP;Shi X;Roeder RK;Niebur GL
微结构有限元模型已成为分析松质骨的重要工具。稳健、准确和经验证的本构模型将增强这些模型在预测应用中的信心，以及它们作为组织特性的准确测定的有用性。采用μ-CT扫描8个不同供体的股骨颈（n = 3）、大转子（n = 6）和腰椎（n = 1）的人骨小梁标本，并将其转换为基于体素的有限元模型。无侧限单轴压缩和剪切载荷进行了模拟的三个不同的本构模型：基于主应变的模型，Drucker-Lode和Drucker-Prager。后者适用于无穷小和有限的运动学。表观屈服应变表现出最小的依赖性的本构模型，最多16.1%的差异，与运动学配方是有影响力的压缩载荷。在组织水平上，产生的组织的数量和位置是不敏感的本构模型，与Drucker-Lode模型的例外，这表明微损伤与计算模型的相关性并没有提高区分本构关系的能力。总之，组织本构模型不太可能仅从表观水平实验中得到充分验证，因为计算太不敏感，无法识别结果的差异。相反，具有有效屈服面的任何不对称标准都可能适用于大多数骨模型。
Microarchitectural finite element models have become a key tool in analyses of trabecular bone. Robust, accurate, and validated constitutive models would enhance confidence in predictive applications of these models, and in their usefulness as accurate assays of tissue properties. Human trabecular bone specimens from the femoral neck (n = 3), greater trochanter (n = 6), and lumbar vertebra (n = 1) of eight different donors were scanned by μ-CT and converted to voxel-based finite element models. Unconfined uniaxial compression and shear loading were simulated for each of three different constitutive models: a principal strain based model, Drucker-Lode, and Drucker-Prager. The latter was applied with both infinitesimal and finite kinematics. Apparent yield strains exhibited minimal dependence on the constitutive model, differing by at most 16.1%, with the kinematic formulation being influential in compression loading. At the tissue level, the quantities and locations of yielded tissue were insensitive to the constitutive model, with the exception of the Drucker-Lode model, suggesting that correlation of microdamage with computational models does not improve the ability to discriminate between constitutive laws. Taken together, it is unlikely that a tissue constitutive model can be fully validated from apparent level experiments alone, as the calculations are too insensitive to identify differences in the outcomes. Rather, any asymmetric criterion with a valid yield surface will likely be suitable for most bone models.