腰椎间盘层区应变测试及力学性能有限元分析

发布时间：2018-02-13 18:41

本文关键词： 腰椎间盘纤维环数字图像相关技术有限元分析　出处：《天津理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：在临床医学上,腰椎间盘突出症成为越来越常见的疾病,大大加重了病人的经济负担和生活成本。腰椎间盘具有维持脊柱高度和分散载荷,连接上下椎体等作用,由于脊椎承受强度大、频率高的力学环境,椎间盘也极易损伤。腰椎间盘病变的原理较复杂,到目前为止还不能准确解释出原因,但是临床医学表明,生物力学因素是该疾病发生的一个重要因素。所以,从对预防椎间盘疾病的发生着手,需要对腰椎间盘在承受各种载荷时的应力-应变状态进行深入的研究。本文从动物腰椎间盘实验和有限元仿真两个方面进行研究,探讨腰椎间盘不同层区的力学性能以及应力应变规律。在实验部分中,利用猪的腰椎间盘节段进行实验,采用数字图像相关技术、电子万能拉伸试验机等实验仪器,测出纤维环应变的位移场和应变场。采用数值分析方法,得到了纤维环不同分层区域的应力-应变大小关系,并做了对比;腹侧和背侧的轴向应变和径向应变也做了对照;位移场测量实验中,得到了位移场的变化云图。通过本实验还可以得到,椎间盘在承受生理载荷的作用下纤维环呈现出非线性的应力-应变曲线。在有限元仿真中,借助逆向工程技术软件Geomagic studio、医学图像分析软件Mimics、制图软件SolidWorks,并利用有限元分析软件ANSYS构建出腰椎间盘模型,包含髓核、纤维环基质、纤维环纤维和终板,并且赋予合理的单元类型和材料属性。根据临床研究结果,模拟了人类习惯性的三种状态下腰椎体的各部分变化情况,分别为:一模拟在直立行走时腰椎体受到700N的作用载荷;二模拟在静坐时腰椎体受到1000N的作用载荷;三模拟在过度载荷时腰椎体受到5000N的作用载荷;加载方式为均布载荷,选取L1椎体表面458个节点,通过节点均匀施加载荷。仿真结果表明:一是纤维环腹侧的应变大于背侧的,与实验的结论一致;二是承受均布载荷时,纤维环向四周膨出;三是应力最大出现在关节棘突上,应力变化从外层到内层递减。最后采用较为复杂的节点耦合建立刚性域的加载方法,模拟了人在运动时发生侧弯受到20N.m的弯矩作用以及在提起重物时受到50N.m弯矩作用时,讨论了椎间盘各组分的位移场、应力场以及应变场的变化趋势和分布规律,并对此进行了简要的分析。本实验得到的结论对于腰椎间盘疾病防治、腰椎间盘缺损修复以及人工腰椎间盘材料研制等都具有重要的科学意义,并且对椎间盘疾病的临床治疗提供指导意义。
[Abstract]:In clinical medicine, lumbar disc herniation has become a more and more common disease, greatly increasing the economic burden and living costs of patients. The lumbar disc has the function of maintaining the height of the spine and dispersing load, connecting the upper and lower vertebrae, etc. Because of the mechanical environment of high intensity and high frequency, the intervertebral disc is easily damaged. The principle of lumbar disc disease is more complicated, so far it can not explain the cause accurately, but clinical medicine shows that, Biomechanical factors are an important factor in the development of the disease. It is necessary to study the stress-strain state of lumbar intervertebral disc under various loads. The mechanical properties and stress-strain law of different layers of lumbar intervertebral disc were discussed. In the experiment part, the experiment was carried out by using the segment of the lumbar intervertebral disc of the pig, the digital image correlation technique and the electronic universal tensile testing machine, and so on. The displacement field and strain field of fiber ring strain were measured. The stress-strain relationship in different layers of fiber ring was obtained by numerical analysis, and the axial strain and radial strain of ventral side and dorsal side were also compared. In the displacement field measurement experiment, the change cloud picture of displacement field is obtained. Through this experiment, we can also get that the fiber ring of intervertebral disc exhibits nonlinear stress-strain curve under the action of physiological load. In the finite element simulation, With the aid of reverse engineering software Geomagic studio, medical image analysis software Mimics, drawing software SolidWorksand using finite element analysis software ANSYS to construct lumbar intervertebral disc model, including nucleus pulposus, fibrous annular matrix, fibrous annulus fiber and endplate. According to the results of clinical research, the changes of each part of lumbar vertebrae were simulated under the three kinds of human habitual conditions, which were as follows: (1) simulating that the lumbar vertebra was subjected to a load of 700N while walking upright; The second simulates that the lumbar vertebrae is subjected to a load of 1000N during sit-down, and the third is that the lumbar vertebra is subjected to a load of 5000N under excessive load. The loading mode is uniform load, and 458 nodes on the surface of L1 vertebra are selected. The simulation results show that the strain of the ventral side of the fiber ring is greater than that of the dorsal side, which is consistent with the experimental conclusion, the second is that the fiber loop bulges around the joint under uniform load, and the third is that the maximum stress appears on the spinous process of the joint. The variation of stress decreases from outer layer to inner layer. Finally, the loading method of rigid domain is established by using a more complicated node coupling method, which simulates the action of the bending moment of 20N.m in the motion and the bending moment of 50N.m when the heavy object is lifted. The change trend and distribution of displacement field, stress field and strain field of each component of intervertebral disc were discussed, and the results of this experiment were analyzed briefly. The repair of lumbar disc defects and the development of artificial lumbar disc materials are of great scientific significance and provide guidance for the clinical treatment of disc diseases.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R681.53;R318.01

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