不同收敛条件对骨盆三维有限元模型计算结果的影响

目的：探讨不同收敛条件下骨盆三维有限元计算结果的准确性。 方法：利用骨盆环三维有限元模型，给予S1椎体上终板600 N载荷，载荷为一阶线性加载，步长设置为0.1 s。约束股骨上段6个方向自由度。分别计算静态收敛及6个不同质量放大系数下的动态收敛结果，将体外实验结果作为参照，对不同计算结果的准确性进行比较。 结果：静态计算收敛结果最接近体外实验结果，与体外实验结果之间线性回归系数为0.88，随着质量放大系数的增加，计算时间缩短，但计算结果准确性下降，当质量放大系数超过3 000时，计算结果与静态计算结果差异有显著性意义(P < 0.05)，回归系数低于0.8。 结论：对于接触较为复杂的骨盆有限元模型，如果静态计算无法收敛，可通过动态算法进行近似求解，并利用合理的质量放大系数降低计算成本，但应确保计算结果误差在合理的范围内。

Effect of different convergent conditions on accuracy of simulation results from a three dimensional finite element model of the pelvic ring

OBJECTIVE: To explore the effect of different convergent conditions on accuracy of simulation results from a three dimensional finite element model of the pelvic ring. METHODS: A first-order linear load of 600 was applied on the S1 vertebral endplate in an established three-dimensional finite element model. The step length was set to 0.1 s. The boundary condition was set as constraint of 6 degrees of freedom in the proximal femur. Static and dynamic explicit convergences with 6 different weight scale factors were calculated retrospectively, and all the simulated results were compared with the experimental results in order to verify the accuracy. RESULTS: The static convergence predicted most accurate with the linear regression coefficient 0.88. With the increase of weight scale factor, the time cost decreased. However, the accuracy of the predicted results decreased. There was statistically difference between the simulation results and experimental results when the weight scale factor achieved 3 000 (P < 0.05) and the coefficient of linear regression was lower than 0.8. CONCLUSION: It suggested that as for the complex finite element model, especially when the model contains complex contact conditions, dynamic explicit convergence can be an alternative solution to static convergence if the latter failed. Also proper weight scale factor should be used to decrease the time cost under the condition that the error was in the limited.