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Biomechanics of blunt liver injury: Relating internal pressure to injury severity and developing a constitutive model of stress-strain behavior.

机译：钝性肝损伤的生物力学：将内压与损伤严重程度相关，并建立应力应变行为的本构模型。

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摘要

Research suggests that in certain types of blunt liver trauma the mechanism of injury is linked to rapid increases in internal pressure within the liver. The objectives of this study were (1) to characterize the relationship between impact-induced pressures and blunt liver injury in an ex vivo organ experimental model; (2) to compare human liver intra-parenchymal pressure and vascular pressure with other biomechanical variables as predictors of liver injury risk; (3) to investigate the feasibility of measuring liver vascular pressure in impacts to pressurized full body post-mortem human subjects (PMHS); and (4) to develop a constitutive model of the mechanical behavior of human liver tissue in blunt impact loading.; Test specimens included 19 ex vivo porcine livers, 14 ex vivo human livers, and 2 full body PMHS. Specimens were perfused with normal saline solution at physiological pressures, and a drop tower applied blunt impact at varying energies. Impact-induced pressures were measured by transducers in the hepatic veins and parenchyma (caudate lobe) of ex vivo specimens. Binary logistic regression demonstrated that tissue pressure measured in the parenchyma was the best indicator of serious liver injury risk (p = .002, Pseudo-R2 = .78). A peak tissue pressure of 48 kPa was correlated to 50% risk of serious (AIS ≥ 3) liver injury. A burst injury mechanism directly related to hydrostatic pressure is postulated for the ex vivo liver loaded dynamically in a drop test experiment. A constitutive model previously developed for finite strain behavior of amorphous polymers was adapted to model liver stress-strain behavior observed in the ex vivo human liver impacts. The model includes six material properties and captures three features of liver stress-strain behavior in impact loading: (1) a relatively stiff initial modulus; (2) a rate-dependent yield or rollover to viscous "flow" behavior; and (3) strain hardening at large strains.; Results of this research could be applied to improve the abdominal injury assessment capabilities of both anthropomorphic crash dummies and finite element human body models used in vehicle safety research.
机译：研究表明，在某些类型的钝性肝外伤中，损伤的机制与肝脏内压的快速升高有关。这项研究的目的是（1）在离体器官实验模型中表征撞击引起的压力与钝性肝损伤之间的关系； （2）将人的肝实质内压力和血管压力与其他生物力学变量作为肝损伤风险的预测指标进行比较； （3）研究在加压的人体尸体受压（PMHS）冲击中测量肝脏血管压力的可行性； （4）建立人肝组织在钝器冲击载荷下力学行为的本构模型。测试样本包括19个离体猪肝，14个离体人肝和2个全身PMHS。在生理压力下，用生理盐水灌注标本，并在不同的能量下，通过落塔施加钝器。通过换能器测量离体标本的肝静脉和实质（尾状叶）中的冲击诱导压力。二元逻辑回归表明，在实质中测量的组织压力是严重肝损伤风险的最佳指标（p = .002，Pseudo-R2 = .78）。组织峰值压力为48 kPa与严重肝损伤（AIS≥3）的50％风险相关。在跌落试验实验中，假设动态加载的离体肝脏具有与静水压直接相关的爆发损伤机制。先前针对无定形聚合物的有限应变行为开发的本构模型适用于模拟在离体人类肝脏撞击中观察到的肝应力-应变行为。该模型包括六个材料属性，并捕获了冲击载荷下肝脏应力-应变行为的三个特征：（1）相对较硬的初始模量； （2）取决于速率的产量或转换为粘性“流动”行为； （3）大应变时的应变硬化。该研究结果可用于提高拟人碰撞假人和用于车辆安全性研究的有限元人体模型的腹部损伤评估能力。

著录项

  • 作者

    Sparks, Jessica L.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Applied Mechanics.; Engineering Biomedical.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 162 p.
  • 总页数 162
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 应用力学;生物医学工程;
  • 关键词

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