Mirzaei Majid, Keshavarzian Maziyar, Naeini Vahid
Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box: 14115-143, Tehran, Iran.
Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box: 14115-143, Tehran, Iran.
Bone. 2014 Jul;64:108-14. doi: 10.1016/j.bone.2014.04.007. Epub 2014 Apr 13.
This paper presents a novel method for fast and reliable prediction of the failure strength of human proximal femur, using the quantitative computed tomography (QCT)-based linear finite element analysis (FEA). Ten fresh frozen human femora (age: 34±16) were QCT-scanned and the pertinent 3D voxel-based finite element models were constructed. A specially-designed holding frame was used to define and maintain a unique geometrical reference system for both FEA and in-vitro mechanical testing. The analyses and tests were carried out at 8 different loading orientations. A new scheme was developed for assortment of the element risk factor (defined as the ratio of the strain energy density to the yield strain energy for each element) and implemented for the prediction of the failure strength. The predicted and observed failure patterns were in correspondence, and the FEA predictions of the failure loads were in very good agreement with the experimental results (R2=0.86, slope=0.96, p<0.01). The average computational time was 5 min (on a regular desktop personal computer) for an average element number of 197,000. Noting that the run-time for a similar nonlinear model is about 8h, it was concluded that the proposed linear scheme is overwhelmingly efficient in terms of computational costs. Thus, it can efficiently be used to predict the femoral failure strength with the same accuracy of similar nonlinear models.
本文提出了一种基于定量计算机断层扫描（QCT）的线性有限元分析（FEA）快速可靠地预测人类近端股骨破坏强度的新方法。对10根新鲜冷冻的人类股骨（年龄：34±16岁）进行了QCT扫描，并构建了相关的基于三维体素的有限元模型。使用专门设计的固定框架为有限元分析和体外力学测试定义并维持一个独特的几何参考系统。在8种不同的加载方向上进行了分析和测试。开发了一种新的方案来分类单元风险因子（定义为每个单元的应变能密度与屈服应变能之比），并用于预测破坏强度。预测的和观察到的破坏模式一致，有限元分析对破坏载荷的预测与实验结果非常吻合（R2 = 0.86，斜率 = 0.96，p < 0.01）。对于平均单元数为197,000的情况，平均计算时间为5分钟（在普通台式个人计算机上）。注意到类似非线性模型的运行时间约为8小时，得出的结论是，所提出的线性方案在计算成本方面具有极高的效率。因此，它可以以与类似非线性模型相同的精度有效地用于预测股骨破坏强度。
