Direct measurement of transverse residual strains in aorta
Direct measurement of transverse residual strains in aorta
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DOI：
10.1152/ajpheart.1996.270.2.h750
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发表时间：
1996-02-01
影响因子：
4.8
通讯作者：
Fung, YC
中科院分区：
文献类型：
--
作者：
Han, HC;Fung, YC
在猪主动脉中测量残余应变。从主动脉垂直于其纵轴切下节段。在无负载状态下，将水不溶性黑色油墨的微粒喷洒到片段的横截面上。然后径向切割节段，并接近截面零应力状态。从在无负荷状态和零应力状态下拍摄的照片中数字化所选微粒（2-20 μ m）的坐标。从微粒的位移计算横截面中的残余应变。由空载状态和零应力状态下的周向长度计算出内壁和外壁上的周向残余应变。结果表明，主动脉壁的周向残余应变在内层为负（压缩），在外层为正（拉伸），而径向残余应变在内层为拉伸，在外层为压缩。这种残余应变分布降低了生理负荷下主动脉中的应力集中。实验结果与圆柱模型的理论估计值进行了比较。残余应变存在地区差异，差异有显著性（P < 0.01），主动脉的升、降胸和腹部区域的内壁上的周向残余应变分别为-0.133 +/- 0.019、-0.074 +/- 0.020和-0.046 +/- 0.017（平均值+/- SD）。一个片段的更多径向切割没有产生显著的额外应变。这意味着一次径向切割后的主动脉段可被视为零应力状态。
Residual strains were measured in the porcine aorta. Segments were cut from the aorta perpendicular to its longitudinal axis. Microdots of water-insoluble black ink were sprinkled onto the transverse sectional surface of the segments in the no-load state. The segments were then cut radially, and sectional zero-stress states were approached. The coordinates of selected microdots (2-20 mu m) were digitized from photographs taken in the no-load state and the zero-stress state. Residual strains in the transverse section were calculated from the displacement of the microdots. The circumferential residual strains on the inner wall and outer wall were calculated from the circumferential lengths in the no-load state and the zero-stress state. Results show that the circumferential residual strain is negative (compressive) in the inner layer of the aortic wall and positive (tensile) in the outer layer, whereas the radial residual strain is tensile in the inner layer and compressive in the outer layer. This residual strain distribution reduces the stress concentration in the aorta under physiological load. The experimental results compared well with theoretical estimations of a cylindrical model. Regional difference of the residual strain exists and is significant (P < 0.01), e.g., the circumferential residual strains on the inner wall of the ascending, descending thoracic, and abdominal regions of the aorta are -0.133 +/- 0.019, -0.074 +/- 0.020, and -0.046 +/- 0.017 (mean +/- SD), respectively. More radial cuts of a segment produced no significant additional strains. This means that an aortic segment after one radial cut can be considered as the zero-stress state.