腹主动脉瘤壁应力应变关系的测量

Measurement of stress-strain relationship of human abdominal aortic aneurysm

目的对腹主动脉瘤壁进行单轴拉伸试验,研究其应力应变关系、极限应力和极限应变。方法腹主动脉瘤壁样品置于拉伸试验机下进行单轴拉伸直至断裂,记录拉伸过程中拉力和变形,计算应力应变关系曲线、极限应力、极限应变。分别使用指数函数和二次多项式对应力应变关系曲线进行拟合,其决定系数R2。结果指数函数方法拟合,R2的平均值为92.04%±5.42%。二次多项式拟合,R2的平均值为98.47%±1.17%。独立样本t检验显示多项式曲线拟合的R2显著大于指数函数(P<0.01)。瘤壁的极限应力为(0.809 4±0.384 2)MPa,极限应变为0.349 3±0.089 1。结论拉伸试验可用于测量腹主动脉瘤的应力应变关系、极限应力和极限应变。使用二次多项式拟合的准确性优于指数函数。

Objective Tensile test of abdominal aortic aneurysm wall was performed to study its stressstrain relationship, ultimate stress and ultimate strain. Methods Tissue samples of human abdominal aortic aneurysm （AAA） were tensed uniaxially on a tensile-testing machine until broken,and the data of the load and elongation in the course were recorded. The stress-strain relationship curve,the ultimate stress and ultimate strain were calculated. Exponential curve and second-order polynomial curve were both used to fit the stress-strain curve,and then estimate the two means by comparing the coefficients of determination of the fitting curves （ R square,R2 ）. Results For exponential curve fitting,the average of R2 was 92, 04%±5. 42%. For polynomial curve fitting,the average of R2 was 98.47% ± 1.17%. The R2 for polynomial curve was significantly （P 〈 0.01 ） greater than that of exponential curve by an independent samples t-test. The ultimate stress and ultimate strain of AAA were （0.809 4 ± 0.384 2） MPa and 0.349 3 ± 0.089 1 respectively. Conclusion Tensile test is able to apply measurement of AAAs mechanical properties including the stress-strain relationship curve, the ultimate stress and ultimate strain. Second-order polynomial curve fitting provides a better description than exponential curve for the stress versus strain relationship of AAA.