PurposeThe properties of the biomaterial are normally characterized by heterogeneity on all scales influencing the function and biomechanics. Elastic modulus (EM), which is one of the most important mechanical properties of material, is necessary for finite element modeling and needed to be determined by some methods. The aim of this study is to demonstrate the feasibility of assessment of EM from GrayValue (GV) of computed tomographic image and assignment of material properties in heterogeneous finite element modeling for studying the performance of the mandibular bones. MethodsThree mandibles obtained from fresh human cadavers were used in this study. All mandibular bones were scanned using computed tomography, and the original data were stored in optical disks. The finite element modeling of the 3 mandibles was meshed using Materialise Mimics 10.01 and Abaqus 6.10 software. Using the empirical expression on relationship between GV and EM, the empirical EM of the meshed mandibular elements were calculated. To verify the empirical EM, actual EM of the three was determined by nanoindentation test using Oliver and Pharr method. The dependence of EM on test regions and loading directions were also discussed. ResultsThe empirical EM of the mandible element is in the range of 3.7 to 23.4 Gpa, and EM of the cortical element is in the range of 8.6 to 13.6 Gpa. In comparison, the actual EM of cortical bone tested by nanoindentation method is in the range of 10.0 to 22.0 Gpa. The tested EM is varied with the test regions and loading directions. The difference in the values of EM determined by the empirical analysis and by the nanoindentation test is approximately 5.0 Gpa. ConclusionsA mandibular finite element model with heterogeneous material properties is built. By analyzing the EM value of this model, it is concluded that the actual EM in anterior-posterior direction in mandibular ramus and EM in superior-inferior direction in mandibular body match the empirical EM better than the other directions.

中文翻译：

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有限元建模中的材料分配

目的生物材料的特性通常以影响功能和生物力学的所有尺度上的异质性为特征。弹性模量（EM）是材料最重要的机械性能之一，对于有限元建模是必需的，并且需要通过某些方法确定。这项研究的目的是证明在研究下颌骨性能的非均质有限元建模中，从计算机断层图像的GrayValue（GV）评估EM以及分配材料属性的可行性。方法采用新鲜人尸体获得的3个下颌骨进行研究。使用计算机断层扫描技术扫描所有下颌骨，并将原始数据存储在光盘中。使用Materialize Mimics 10.01和Abaqus 6.10软件对3个下颌骨的有限元建模进行了网格划分。使用关于GV和EM之间关系的经验表达式，计算了网状下颌元素的经验EM。为了验证经验EM，通过使用Oliver和Pharr方法的纳米压痕测试确定了这三个样品的实际EM。还讨论了EM对测试区域和加载方向的依赖性。结果下颌骨元素的经验EM在3.7至23.4 Gpa的范围内，而皮层元素的EM在8.6至13.6 Gpa的范围内。相比之下，通过纳米压痕法测试的皮质骨的实际EM在10.0至22.0 Gpa的范围内。测试的EM随测试区域和加载方向而变化。通过经验分析和纳米压痕测试确定的EM值差异约为5.0 Gpa。结论建立了具有异质材料特性的下颌有限元模型。通过分析该模型的EM值，可以得出结论，下颌支的前后方向上的实际EM和下颌体上下方向上的EM与其他方向上的经验EM更好地匹配。