Functional Morphology and Evolution Unit, Hull York Medical School, University of York, UK.
J Biomech. 2010 May 28;43(8):1603-11. doi: 10.1016/j.jbiomech.2009.12.027. Epub 2010 Feb 21.
Finite element analysis (FEA) is a fundamental method to study stresses and strains in complex structures, with the accuracy of an FEA being reliant on a number of variables, not least the precision and complexity of the model's geometry. Techniques such as computed tomography (CT) allow general geometries to be derived relatively quickly; however, constraints on CT image resolution mean defining subcortical geometries can be problematic. In relation to the overall mechanical response of a complex structure during FEA, the consequence of variable subcortical modelling is not known. Here we test this sensitivity with a series of FE models of a macaque mandible with different subcortical geometries and comparing the FEA strain magnitudes and orientations. The validity of the FE models was tested by carrying out experimental strain measurements on the same mandible. These strain measurements matched the FE predictions, providing confidence that material properties and model geometry were suitably defined. Results of this study show that cortical bone alone is not as effective in resisting bending as it is when coupled with subcortical bone, and as such subcortical geometries must be modelled during an FEA. This study demonstrates that the fine detail of the mandibular subcortical structure can be adequately modelled as a solid when assigned an appropriate Young's modulus value, in this case ranging from 1 to 2 GPa. This is an important and encouraging result for the creation of FE models of materials where CT image resolution or poor preservation prevent the accurate modelling of subcortical bone.
有限元分析（FEA）是研究复杂结构中的应力和应变的基本方法，FEA 的准确性取决于许多变量，尤其是模型几何形状的精度和复杂性。计算机断层扫描（CT）等技术可以相对快速地得出一般的几何形状；然而，CT 图像分辨率的限制意味着定义皮质下的几何形状可能会出现问题。就复杂结构在 FEA 中的整体力学响应而言，皮质下建模的变化会带来什么后果尚不清楚。在这里，我们使用一系列具有不同皮质下几何形状的猕猴下颌骨的 FEA 模型来测试这种敏感性，并比较 FEA 应变幅度和方向。通过对同一下颌骨进行实验应变测量来验证 FE 模型的有效性。这些应变测量与 FE 预测相匹配，这提供了对材料特性和模型几何形状的适当定义的信心。这项研究的结果表明，皮质骨单独抵抗弯曲的效果不如与皮质下骨结合时好，因此在 FEA 中必须对皮质下几何形状进行建模。这项研究表明，当下颌骨皮质下结构的细节被赋予适当的杨氏模量值（在这种情况下，范围为 1 到 2 GPa）时，可以将其充分地建模为实体。对于创建 CT 图像分辨率或保存不善会妨碍皮质下骨精确建模的材料的 FE 模型，这是一个重要且令人鼓舞的结果。
