复合绝缘子芯棒疲劳断裂特性分析

ANALYSIS ON THE FATIGUE FRACTURE CHARACTERISTICS OF COMPOSITE INSULATOR CORE ROD

在自制疲劳试验机上模拟了复合绝缘子实际运行时的疲劳损伤过程,分别讨论了摆动幅度和扭转角度对绝缘子疲劳寿命的影响。并采用超景深三维显微系统测量了绝缘子断口表面形貌,利用分形几何学理论定量表征了断口表面形貌。研究表明,芯棒疲劳断裂是在循环应力的作用下,芯棒裂纹逐渐深化直至大量纤维断裂的过程。断口表面分形维数介于2～3之间,且线性回归相关系数都在0.99以上,强的相关性表明断口表面分形维数具有明显的分形特征;断口形貌的形成不仅受载荷产生的形变影响,也与载荷循环次数有关,断口表面分形维数与其受到的载荷呈正相关,与应力循环次数呈负相关关系。

In order to analyze the fatigue fracture surface characteristics of composite insulator core rod,the fatigue damage process of insulators under different amplitude/torsion angle conditions was simulated by dynamic load fatigue test.The surface morphology of insulator fracture was observed by using an super deep scene 3D microscope,and combined with fatigue loads and the number of stress cycles,the formation mechanism of the fracture surface was analyzed.The fractal geometry theory was used to describe the complexity of the fracture morphology in quantitatively and discussed the relationship between the fractal dimension and the fatigue loads.The results show that the fatigue fracture process of core rod is actually a stress corrosion process,which means that under the action of stress,the crack of the fiber gradually deepens until it breaks.The deformation and abrasion caused by the cyclic stress all determined the fracture surface morphology.The fractal dimension of the fracture surface is between 2 and 3,and the linear regression correlation coefficient is above 0.99,the strong correlation shows that the fracture surface of the insulator has obvious fractal characteristics.The formation of the fracture surface is not only related to the deformation,but also related to the number of stress cycles.The fractal dimension of the fracture surface is positively correlated with the loads and negatively correlated with the number of load cycles.