不同数值方法模拟皮质骨结构弯曲断裂的准确性

Fracture accuracy on cortical bone structure under bending load using different numerical methods

背景:当前针对皮质骨结构的断裂模拟主要有基于单元瞬时失效、连续损伤力学以及扩展有限元理论3种方法。虽然断裂模拟文献众多,但却鲜有研究比较3种断裂方法的模拟精度。目的:探究3种数值方法模拟皮质骨结构弯曲断裂的准确性与适用性。方法:首先针对大鼠股骨样本进行三点弯曲实验,然后依据样本微观扫描影像建立大鼠股骨有限元模型,分别采用3种数值方法模拟皮质骨结构在三点弯曲载荷下的断裂,通过将预测断裂载荷及断裂模式与实验结果进行对比,以判定各方法模拟皮质骨结构弯曲断裂的准确性。结果与结论:①由于单元失效策略不同,3种数值方法针对同一股骨有限元模型预测所得断裂进程存在明显差异;②结果显示基于连续损伤力学理论的断裂模拟与实验结果一致性更好;③通过与实验对比可以找到更适合模拟皮质骨结构弯曲断裂的数值方法,通过观测不同数值方法预测断裂参数差异并解析差异存在的原因,能够为各数值方法确定断裂模拟的适用范围,以提高仿真精度。

BACKGROUND:Current fracture simulation for cortical bone structure is mainly based on three numerical methods:the element instantaneous failure,continuum damage mechanics,and extended finite element methods.Although many studies focus on cortical bone fracture simulation,few have compared the differences in prediction accuracy using the three numerical methods.OBJECTIVE:To probe the accuracy and applicability of the three numerical methods in simulating cortical bone fracture under bending load.METHODS:The rat femur samples were primarily used to perform the three-point bending experiment.The rat femoral finite element models were established based on the micro-CT images of the femur samples and the three numerical methods were used to conduct the fracture simulations under three-point bending loads.The predicted fracture loads and fracture patterns were compared with the experimental data to determine the accuracy of various numerical methods in simulating cortical bone fracture.RESULTS AND CONCLUSION:(1)The discernible differences in the failure processes could be observed in the same finite element model under the three numerical simulations due to different element failure strategies.(2)The simulation results showed that the fracture simulation using the continuum damage mechanics method was in better agreement with the experimental results.(3)The numerical method that was suitable for simulating cortical bone fracture under bending load could be determined by comparing it with experimental results.The variations in the fracture parameters were observed,and the reason for the differences in the predicted results using different numerical methods was also discussed,which aided in determining the range of applicability of structural fracture simulation for each numerical method and then improving the simulation accuracy.