捻绳的分形维数对其拉伸性能的影响

Effect of Twisted Ropes Fractal Dimensions on Their Tensile Properties

分形结构维数是描述无序系统多级自相似结构特征的有效方式,并可以将捻绳的结构与其力学性质联系起来。通过观察捻绳的堆砌方式,并绘制了均等面积和圆形化的捻绳理论截面图,并求得了对应的分形维数;用WDW-20电子微机控制万能材料试验机测试了几种不同直径的丙纶、涤纶捻绳的拉伸性能。由此讨论了捻绳的断裂强度、初始模量、断裂伸长率和断裂比功与试样的整体分形维数的关系。结果表明,捻绳的整体分形维数与其断裂强度和初始模量呈线性负相关,而与断裂伸长率呈正相关关系。丙纶捻绳的整体分形维数与其断裂比功呈线性负相关,而涤纶捻绳的整体分形维数与其断裂比功呈线性正相关。

Fractal approach is a potentially useful tool to describe the characteristic of hierarchical selfsimilar structure.Particularly,ti is also suitable to link the structure and tensile properties of twisted ropes.Through observing the packing mode of twisted ropes,theoretical images of the twisted ropes with equal-area rounded cross-section are drawn,fractal dimension of them has been calculated;and tensile properties with different diameters were measured by means of WDW-20 Electronic Universal Tester.Correlation between the fractal dimension and its breaking tenacity,initial modulus,extension at break,and specific work of rupture were discussed.Experimental results indicate that fractal dimension of the twisted ropes is negatively correlated with its breaking tenacity and initial modulus,and positively with extension at break.However,fractal dimension of polypropylene twisted ropes is negatively correlated with its specific work of rupture,while fractal dimension of polyester twisted ropes is positively correlated with its specific work of rupture.