脊椎-脑脊液流固耦合模型的有限元分析

Finite Element Analysis of Fluid-solid Coupling Model for Spine-cerebrospinal Fluid

目的研究脊椎在脑脊液流体力学作用下应力载荷分布,为开发脑脊液生物反应器提供方案支持和实验数据支撑。方法合理设定阈值,利用CT数据建立脊椎-脑脊液流固耦合模型;对三维模型进行结构化网格划分预处理后,采用有限元分析软件进行力学模拟仿真;对比分析脑脊液流速分别为5cm/s、8cm/s及12cm/s条件下,硬脊膜及脊椎的应力分布与形变。结果脑脊液流动过程中,其表面速度由多个切向分量构成,在硬脊膜横截面的曲率最大处,产生了最大速度矢量值,且当流速为5cm/s、8cm/s和12cm/s时,该值分别为13.42cm/s、16.29cm/s和58.78cm/s。3种流速下,硬脊膜的最大应力分别为4.3837×10^-5 Mpa、7.3233×10^-5 Mpa和3.1131×10^-4 Mpa;位移量分别为0.1317cm、0.2007cm和0.5509cm。脊椎应力最大值分别为5.5856×10^-5 Mpa、8.7411×10^-5 Mpa和6.9357×10^-4Mpa。结论脑脊液流速增大会导致脊椎骨应力增加;应力变化对周围组织产生横向位移,导致应力向周围组织扩散。

Objective To support the development of a cerebrospinal fluid bioreactor,the influence of flow velocity on spinal strain distribution was studied.Methods A spine-cerebrospinal fluid-solid composite model was established by setting threshold reasonably and using CT data.The strain distribution of the model was simulated using finite element analysis software after pretreatment of structured mesh generation for three-dimensional model.Under 5 cm/s,8 cm/s and 12 cm/s cerebrospinal fluid flow rates,the strain on vertebra as well as the stress and deformation of the dura mater were analyzed.Results The surface velocity of cerebrospinal fluid was composed of multiple tangential components.At the maximum curvature of the dura's cross section,a large velocity vector was generated.When the cerebrospinal fluid flow rates were 5 cm/s,8 cm/s and 12 cm/s,the maximum velocity vector values were 13.42 cm/s,16.29 cm/s and 58.78 cm/s respectively.At these three flow rates,the maximum stresses on the dura mater were 4.3837×10^-5 Mpa,7.3233×10^-5 Mpa and 3.1131×10^-4 Mpa and the displacements were 0.1317 cm,0.2007 cm and 0.5509 cm respectively.The maximum stresses on the spine were 5.5856×10^-5 Mpa,8.7411×10^-5 Mpa,and 6.9357×10^-4 Mpa.Conclusion The pulsation of cerebrospinal fluid exerts a stress on the dura mater,and the increasing flow rate of cerebrospinal fluid leads to an increase of the pressure on vertebrae.The stress change can induce a lateral displacement on the surrounding tissue,giving rise to the strain spreading to surrounding tissues.