Vawter D L, Fung Y C, West J B
J Appl Physiol Respir Environ Exerc Physiol. 1978 Aug;45(2):261-9. doi: 10.1152/jappl.1978.45.2.261.
An experimental procedure was developed to measure the stress-strain relationship on rectangular slabs (5.0 X 5.0 X 0.5 cm) of excised dog's lung. The slabs were subjected to biaxial loading and the resulting triaxial deformations were measured. Deformations were measured in the central portion of the specimen by video dimension analysers in order to minimize boundary effects. Specimen thickness was measured with a magnetic reluctance proximeter system. The data were sampled and stored on-line by a PDP-8E computer. An electromechanical servo system was used to control the lateral force. Tests were performed at several pH values and at 20 and 37 degrees C. The tissue exhibited a highly nonlinear stress-strain relationship, compliant at low stress levels and stiff when the stress was high. Hysteresis was observed to be about 28% and was unaffected by a 250-fold change in strain rate. Biaxial loading revealed a new characteristic: there is a change in elastic behavior when the tissue undergoes a compressive strain. When the tissue was in tension increasing the lateral load decreased the compliance, but the opposite was true when compressive strain was present.
已开发出一种实验程序，用于测量切除的犬肺矩形薄片（5.0×5.0×0.5厘米）的应力-应变关系。这些薄片承受双轴载荷，并测量由此产生的三轴变形。为了使边界效应最小化，通过视频尺寸分析仪在标本的中心部分测量变形。用磁阻测厚仪系统测量标本厚度。数据由一台PDP - 8E计算机在线采样并存储。使用机电伺服系统控制侧向力。在几个pH值以及20和37摄氏度下进行测试。该组织呈现出高度非线性的应力-应变关系，在低应力水平下柔顺，在高应力时变硬。观察到滞后约为28%，并且不受应变率250倍变化的影响。双轴加载揭示了一个新特性：当组织经历压缩应变时，其弹性行为会发生变化。当组织处于拉伸状态时，增加侧向载荷会降低柔顺性，但当存在压缩应变时情况则相反。
