Evaluation Of Thermal Deformation And Influences Of Related Factors For Polyvinyl Chloride Insulation Of Cable

Defects,such as deformation and cracking,can be generated at the insulation of wires and cables due to high temperature and external mechanical action after long-time service.These factors will contribute to the accelerated ageing of cables and seriously impact on the service life and safe use of cables and even endanger the person security.Therefore,studying on related factors for evaluation of thermal deformation of cables is of great significance to improve the quality of cables and guarantee the property and personal safety.Studying on experiment and related factors of thermal deformation and finite element analysis for polyvinyl chloride insulation of cable were carried out.The main research work and conclusions drawn were summarized as follows:(1)The differences in thermal deformation test in the domestic and foreign standards were compared.Shortcomings in the current domestic standard were showed.The results indicated that international standard IEC 60811-508:2017 is a relatively perfect test standard of thermal deformation for cable at present and suitable for the Chinese standardization systems.(2)Thermal deformation test for polyvinyl chloride insulation of cable was performed by the international standard IEC 60811-508:2017,with the strategy of controlling variables employed.Related factors(e.g.temperature,loading level)to thermal deformation of insulation of polyvinyl chloride cable were analyzed.Meanwhile,the morphologies of test pieces were included and the morphology characteristics at the indentation position were discussed.The results indicated that the thermal deformation of insulation of polyvinyl chloride cable is significantly reduced and the number of the craze at the indentation increases with the temperature and the loading level.(3)Finite element analyses on thermal deformation process for polyvinyl chloride insulation of cable were carried out by using quasi-static analysis based on ABAQUS/Explicit.The finite element results were verified by the experimental results,indicating an adequate solution of thermal deformation behavior.(4)Thermal deformation behaviors for various structural parameters with standard loading levels were studied.The fitting functions of the indentation percentage and structural parameters of insulation with a given cross-sectional area were obtained,as well as that of the structural parameters and cross-sectional areas for a given thermal deformation level.Insulation thickness meeting the indicator for thermal deformation can be predicted.The work can provide some references for designing insulation thickness of wire and cable products.