Numerical Analysis And Experimental Study On The Bearing Performance Of Post Insulators

Pillar insulator is the most common support structure of electrical equipment, usually assembled by the upper and lower metal fittings and ceramic column with plastic, which mainly provide axial support and bending resistance to electrical equipment.With electricity accidents caused by insulator failure increasing year by year, mechanical strength and dynamic properties of the insulator received more attention, but the current research about insulator is mainly based on stress analysis of linear material, which has a certain reference value for the insulator structure design. However, the studies about influence of initial imperfection on the mechanical properties of the insulator and the mechanism of the main failure modes were few.So experimental and simulation methods were combined to study damage accumulation in the insulator binding layer under static and dynamic load and the related mechanism of debonding failure.Firstly,to obtain the elastic parameters of the column by bending experiments on the same batch of porcelain insulators, and to observe the failure forms of the specimen at the same time.Through the experimental data collected to calculate the ultimate flexural strength of the insulator, which provide experimental data support for the next finite element simulation of binding layer debonding under static loads. Secondly, the cohesive injury units were used to simulate the interface separating phenomenon of binding layer under bending load, the initiation, extended until failure of the entire process can be intuitive showed, and the impact of different interface parameters on structure flexural strength was analyzed;Meanwhile, in this paper, the response characteristics of insulator composite structure under dynamic load was analyzed, as well as the material damage accumulation process under dynamic loading and its effect on the structural dynamic characteristics.Through the above researches, this paper reached the following conclusions:(1) the results of experiment and simulation analysis of binding layer debonding failure showed that the initial crack surface located at the bottom of the binding layer with flange joints, The position of the interface stress develops fastest, and leads to the rapid expansion of the crack;Increase the ultimate strength and fracture energy of interface layer within a certain range can improve bending resistance of insulator, but little impact on the ultimate bearing capacity after more than a certain value;(2) Through dynamic experiments and simulation analysis of series composite insulators, the insulator binding layer with a certain degree of damage has less impact on the dynamic characteristics of the overall structure under dynamic loading, dynamic characteristics of the overall structure have a more significant performance only when there was serious damage with binding layer. During the experiment, except through the changes of dynamic characteristics and the analysis of displacement-time process under load before and after to determine the extent of structure damage, the damage situation of key parts, such as binding layer, should be carefully examined.