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首页> 外文学位 >MECHANICAL FACTORS AND THE THRESHOLD OF TRAUMA OF THE INTERVERTEBRAL JOINT - A FINITE ELEMENT ANALYSIS WITH EXPERIMENTAL VALIDATION (SPINAL INJURY, NONLINEAR, FUNCTIONAL UNIT/DISC, MATHEMATICAL MODEL, LOW BACK PAIN).
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MECHANICAL FACTORS AND THE THRESHOLD OF TRAUMA OF THE INTERVERTEBRAL JOINT - A FINITE ELEMENT ANALYSIS WITH EXPERIMENTAL VALIDATION (SPINAL INJURY, NONLINEAR, FUNCTIONAL UNIT/DISC, MATHEMATICAL MODEL, LOW BACK PAIN).

机译：椎间关节创伤的力学因素和阈值-带有实验验证的有限元分析（脊髓损伤，非线性，功能单元/光盘，数学模型，下背部疼痛）。

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摘要

Experimental and analytical finite element analyses were conducted to determine the effects of external load resulting in spinal injury.; Axial compressive loading on human thoracolumbar functional units exhibits initial ambient, physiologic, traumatic and post traumatic loading phases. Initiation of trauma was defined as the point where the instantaneous tangent stiffness of the structure begins to decrease for the first time. For both normal and degenerate segments this microfailure load was 80% of the conventional traumatic failure load. The more flexible degenerate spines resulted in a lower value for these loads. Hypotheses regarding these microfailures which were not obvious on radiographs, were confirmed by morphologic cryosections. The energy absorbed by normal discs between microfailure and traumatic failure was 43% of total energy required for traumatic failure. In degenerate discs this was 28%. This may be an important index in determining the reserve strength after the initiation of injury.; A materially and geometrically non-linear axisymmetric finite element model was constructed using geometry from experimental records. The purpose was to estimate the load dependent material constants and to explain the mechanics of injury based on regional strain energy density distribution. Experimental load-deflection data was used for validation. A critical evaluation of the inverse finite element method typically used for such estimations revealed the importance of obtaining the deformation data from a large number of experimental measurements. Results indicated the Young's modulus value of the annulus fibrosus to be the highest in the physiologic loading phase. It reduced in the traumatic phase after the initiation of trauma. Stress-deformation analysis included the strain energy, annulus and endplate stresses, and nucleus pressure distributions, from the ambient to traumatic phases. The structure exhibited a concentration of strain energy density at the annulus-endplate junction near the outer disc circumference. A gradual yielding of the junction results in a settlement of the supports of the endplate at its outer edges. Due to external load and internal nucleus pressure, this support yielding phenomenon adds to its instability producing microfailures.; This study has provided experimental evidence and a theoretical basis for the initiation of injury to a functional unit. Microfailures occur at a lower physiological loading than the conventional traumatic failure of the structure.
机译：进行了实验和分析有限元分析，以确定外部负荷对脊柱损伤的影响。人胸腰椎功能单元上的轴向压缩负荷表现出初始的环境，生理，创伤和创伤后负荷阶段。创伤的开始定义为该结构的瞬时切线刚度首次开始下降的点。对于正常段和退化段，此微故障负荷均为常规创伤性故障负荷的80％。退化的脊椎越灵活，导致这些载荷的值越低。形态学冰冻切片证实了有关这些微故障的假说在放射照片上不明显。正常椎间盘在微故障和创伤性衰竭之间吸收的能量占创伤性损伤所需总能量的43％。在退化光盘中，这一比例为28％。这可能是确定损伤开始后的储备力量的重要指标。从实验记录中使用几何构造了材料和几何非线性轴对称有限元模型。目的是估计依赖于载荷的材料常数，并根据区域应变能密度分布来解释损伤的机理。实验载荷挠度数据用于验证。对通常用于此类估计的逆有限元方法的严格评估揭示了从大量实验测量中获取变形数据的重要性。结果表明，在生理负荷阶段，纤维环的杨氏模量值最高。在创伤开始后，在创伤阶段它减少了。应力-变形分析包括从环境阶段到创伤阶段的应变能，环空和端板应力以及核压分布。该结构在圆盘外圈附近的环形端板连接处表现出集中的应变能密度。接合处的逐渐屈服导致端板的支撑在其外边缘处沉降。由于外部载荷和内部核压，这种支持物屈服现象增加了其产生微失效的不稳定性。这项研究提供了实验证据，并为功能单元的损伤引发的理论基础。与结构的常规外伤相比，微故障的生理负荷更低。

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  • 作者

    YOGANANDAN, NARAYAN.;

  • 作者单位

    Marquette University.;

  • 授予单位 Marquette University.;
  • 学科 Engineering Biomedical.
  • 学位 Ph.D.
  • 年度 1985
  • 页码 320 p.
  • 总页数 320
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;
  • 关键词

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