论文标题
在动态应变速率下简单剪切中脑组织的机械表征
Mechanical characterization of brain tissue in simple shear at dynamic strain rates
论文作者
论文摘要
在严重的影响条件下，脑组织会经历快速而复杂的变形，可以看作是压缩，张力和剪切的混合物。此外，当菌株和应变速率分别超过10％和10/s时，动物和人类发生弥漫性轴突损伤（DAI）。因此，在这些菌株和应变速率下了解剪切中脑组织的机械性能至关重要，因为它们可以用于有限元模拟中，以预测在不同影响条件下脑损伤的发生。在这项研究中，开发了一种实验设置，以在猪脑组织<120/s的猪脑组织上进行简单的剪切测试。应变率在30、60、90和120/s时的最大测量剪切应力为1.15 +/- 0.25 kPa，1.34 +/- 0.19 kPa，2.19 +/- 0.225 kpa和2.52 +/- 0.27 +/- 0.27 kpa，分别以shear的最大值，k = 1.。达到了Mooneyrivlin模型）和数值剪切应力（p = 0.7866-0.9935）。还通过数字分析了样品厚度效应（2.0-10-10-10-10-10-10-10毫米厚的样品），我们发现剪切应力幅度没有显着差异（p = 0.9954），表明在简单剪切测试中样品的均匀变形。还以不同的应变幅度（10％-60％菌株）进行了简单剪切中的应力松弛测试，平均上升时间为14 ms。这使我们能够估算弹性和粘弹性参数（MU = 4942.0 PA和Prony参数：G1 = 0.520，G2 = 0.3057，TAU1 = 0.0264 S，TAU2 = 0.011 s），可以在FE中使用FE软件来分析大脑组织的超弹性行为。
During severe impact conditions, brain tissue experiences a rapid and complex deformation, which can be seen as a mixture of compression, tension and shear. Moreover, diffuse axonal injury (DAI) occurs in animals and humans when both the strains and strain rates exceed 10% and 10/s, respectively. Knowing the mechanical properties of brain tissue in shear at these strains and strain rates is thus of particular importance, as they can be used in finite element simulations to predict the occurrence of brain injuries under different impact conditions. In this research, an experimental setup was developed to perform simple shear tests on porcine brain tissue at strain rates < 120/s. The maximum measured shear stress at strain rates of 30, 60, 90 and 120/s was 1.15 +/- 0.25 kPa, 1.34 +/- 0.19 kPa, 2.19 +/- 0.225 kPa and 2.52 +/- 0.27 kPa, (mean +/- SD), respectively, at the maximum amount of shear, K = 1. Good agreement of experimental, theoretical (Ogden and MooneyRivlin models) and numerical shear stresses was achieved (p = 0.7866 - 0.9935). Specimen thickness effects (2.0 - 10.0 mm thick specimens) were also analyzed numerically and we found that there is no significant difference (p = 0.9954) in the shear stress magnitudes, indicating a homogeneous deformation of the specimens during simple shear tests. Stress relaxation tests in simple shear were also conducted at different strain magnitudes (10% - 60% strain) with the average rise time of 14 ms. This allowed us to estimate elastic and viscoelastic parameters (mu = 4942.0 Pa and Prony parameters: g1 = 0.520, g2 = 0.3057, tau1 = 0.0264 s, tau2 = 0.011 s) that can be used in FE software to analyze the hyperviscoelastic behavior of brain tissue.
