Measurement and analysis of ultimate mechanical properties, stress-strain curve fit, and elastic modulus formula of human abdominal aortic aneurysm and nonaneurysmal abdominal aorta
Measurement and analysis of ultimate mechanical properties, stress-strain curve fit, and elastic modulus formula of human abdominal aortic aneurysm and nonaneurysmal abdominal aorta
复制标题
人体腹主动脉瘤和非动脉瘤腹主动脉极限力学性能、应力应变曲线拟合及弹性模量公式的测量与分析
DOI：
10.1016/j.jvs.2007.12.053
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发表时间：
2008-07-01
影响因子：
4.3
通讯作者：
Wu, Jan Guo
中科院分区：
文献类型：
--
作者：
Xiong, Jiang;Wang, Shen Ming;Wu, Jan Guo
目的：对腹主动脉瘤(AAA)和双向非瘤性腹主动脉(NAA)的最大应变、应力、弹性模量和应力-应变曲线进行测量和分析，以获得AAA和NAA的极限力学性能、更接近的应力-应变曲线拟合以及AAA和NAA的弹性模量公式。14份人体AAA样本取自择期动脉瘤修补术患者。以6具身体器官捐献者的6对NAA为对照，共12个NAA样本。将样品安装在拉伸测试机上，施加压力，直到发生断裂。计算了每个试件的最大应变、应力和弹性模量，并绘制了应力-应变曲线。用指数曲线和二次多项式曲线来拟合应力-应变曲线，通过比较决定系数R(代表曲线拟合强度的决定系数)来估计平均值。结果：腹主动脉瘤(AAA)、环状主动脉瘤(CAA)和纵主动脉瘤(LAA)的最大应力无明显差异。然而，AAA的最大应变显著小于双向NAA(P<；.01)。AAA的最大弹性模量显著大于CAA和LAA(P<；分别为0.01和0.05)。二次多项式曲线AAA的W显著大于指数曲线的W(P&t；0.05)。二次多项式公式E=2AX+b，AAA的a平均值显著大于双向NAA的a平均值(P<0.01)，而b的平均值三组间差异无统计学意义(P>；0.05)。拉伸试验测量可以成功地分析AAA和NAA的极限力学性能。在相同的最大应力下，AAA比NAA更硬，膨胀性更小。二次多项式曲线拟合法比指数曲线拟合法能更接近地描述AAA应力-应变曲线。由二次多项式曲线拟合出的弹性模量式的公式变量a可以确定弹性模数的增量趋势，而b对弹性模数的增量趋势影响不大。
Objective: The maximal strain, stress, elastic modulus, and stress-strain curve fitting of abdominal aortic aneurysms (AAA) and bidirectional nonaneurysmal abdominal aorta (NAA) were measured and analyzed to obtain the ultimate mechanical properties, the more approximate stress-strain curve-fitting, and the elastic modulus formula of AAA and NAA.Methods. Fourteen human AAA samples were harvested from patients undergoing elective aneurysm repair. Twelve NAA samples comprised of six longitudinal-circumferential pairs of NAA from six cadaveric organ donors were used as controls. Samples were mounted on a tensile-testing machine and force was applied until breakage occurred. The maximal strain, stress, and elastic modulus were calculated and a stress-strain curve was plotted for each sample. Exponential and second-order polynomial curves were used to fit the stress-strain curve, and the means were estimated by comparing the R (coefficient of determination that represents the strength of a curve fitting). Coefficients of elastic modulus were calculated and analyzed, and the incremental tendency of each modulus was evaluated by comparing the difference of coefficients.Results: There was no significant difference in maximal stress among AAA, circumferential aortic aneurysms (CAA), and longitudinal aortic aneurysms (LAA). However, AAA maximal strain was significantly less (P < .01) than that of bidirectional NAA. AAA maximal elastic modulus was significantly greater than that of CAA and LAA (P < .01 and .05, respectively). W of AAA for second-order polynomial curve was significantly greater (P < .05) than that for the exponential curve. For the elastic modulus formula from the second-order polynomial curve, E = 2ax + b, the average value of a for the AAA was significantly greater (P < .01) than that for the bidirectional NAA, but there was no significant difference (P > .05) among the three groups for the average value of b.Conclusions. Tensile test measurements can successfully analyze ultimate mechanical properties of AAA and NAA. AAA is stiffer and less distensible than NAA under the same maximal stress. Second-order polynomial curve fitting provides a more approximate description for AAA stress-strain curve than exponential curve fitting does. Formula variables a of the elastic modulus formula from second-order polynomial curve fitting can determine the incremental tendency of the elastic modulus, while b has negligible effect on the incremental tendency of the elastic modulus.