中文摘要：

目的利用有限元法动态分析L1在垂直冲击作用力下应力分布及应力变化规律。方法建立胸腰椎（T11．L3）的三维非线性有限元模型，并验证模型的有效性。模拟体外实验，予以100J能量垂直冲击有限元模型，利用Abaqus6．9显式动力学求解器Explict进行求解，分析L1的应力分布特点及变化规律。结果建立了有效的胸腰椎三维非线性有限元模型。在垂直冲击作用下L1应力随时间变化而变化，应力最大值部位随时间变化而变化，应力最大部位出现在椎弓根基底部、关节突关节及峡部，椎弓根基底部应力最大值出现在椎弓根基底部的外下方，应力在此集中并沿椎体壁向前方传递；在椎体后上方出现明显的应力峰值，在椎体前上方应力随时间变化不明显，无明显应力峰值出现。结论所建立的完整胸腰椎三维非线性有限元模型有效，可进行动态分析；椎体后上方应力峰值的出现可能是椎体爆裂性骨折椎管内占位骨折块形成的原因。

英文摘要：

Objective To analyze the stress distribution and variation of the L1 vertebra under vertical impact force with finite element method dynamically. Methods A nonlinear three-dimensional finite-element model of T1 l-L3 segments was establish and verified. The finite element model, which simulated the testing in vitro, was impacted by 100-J energy in vertical direction. The feature and variation of the stress distribution was analyzed by using ABAQUS/EXPLICIT 6. 9 the explicit dynamic finite element solver. Results An effective nonlinear three-dimensional finite-element model was established. Under the vertical impact, the stress and maximum stress location, which appeared in the vertebral arch foundation bottom, joint axon joint and the isthmus, changed with time. The maximal stress appeared and focused in the bottom of the outer base of the pedicle, then the stress passed ahead along the vertebra. The peak stress was found in the upper posterior vertebra but not in the superior part, which did not change significantly over time. Conclusion The nonlinear three-dimensional finite-element model of thoracolumbar spine is and effective method for dynamical analysis. The peak stress of superior- posterior vertebra may lead the vertebral canal to be occupied by bone fragments in thoracolumbar burst fractures.