Junxiong Wu

This study focuses on the semiconductive silicone rubber of 10 kV cold-shrink accessories. Accelerated thermal aging tests were conducted on the semiconductive silicone rubber, obtaining tensile stress–strain curves at various time points after thermal aging. The corresponding parameters of the Yeoh hyperelastic model were calculated. The results indicate that the initial shear modulus of the samples decreases with the increase in the aging temperature and time. Microscopic morphology, changes in cross-sectional content, thermal residual values, and chemical structure changes of the samples after aging were studied using electron microscopy, EDS testing, TG curves, and Fourier spectra. The results show that the surface roughness of the aged semiconductive silicon rubber increases, the residual values decrease, the thermal stability decreases, the main chain absorbance decreases, the main chain integrity decreases, and the organic functional groups Si-CH₃ and Si(CH₃)₂ decrease, leading to a reduction in organic content.

Electrical cable joint silicone rubber insulation is influenced by various factors such as electricity and heat, leading to aging and failure of insulation performance. To non-destructively detect the aging status of silicone rubber, a diagnostic method based on ultrasound velocity for silicone rubber aging status is proposed. Silicone rubber specimens with different aging times were prepared, and their density and elastic modulus were measured. The correlation between silicone rubber ultrasound velocity and aging status was verified through simulation and experimentation. The experimental results showed that the goodness of fit between silicone rubber velocity and aging status was above 0.8. Using ultrasound velocity can accurately characterize the aging status of silicone rubber.

The interface pressure between the cable attachment and the body is crucial for the stable long-term operation of the cable. To solve the issue of interface insulation characteristics’ damage caused by the pressure transducer measurement method, a non-destructive testing method of silicone rubber interface pressure using nonlinear ultrasound is presented. Initially, the study analyzes the propagation characteristics of ultrasonic waves at the interface of cross-linked polyethylene and silicone rubber. The study also establishes the relationship between the nonlinear coefficient and the interface pressure. Subsequently, a nonlinear ultrasonic test platform is constructed using the pulse reflection method to measure the interface pressure of flat silicone rubber and cross-linked polyethylene through nonlinear ultrasonic testing. Theoretical and experimental results indicate that the fundamental amplitude of the frequency domain of the interface reflection wave decreases, and the second harmonic amplitude and nonlinear coefficient both increase as pressure increases. These results demonstrate that the nonlinear ultrasound, non-destructive testing method can accurately evaluate the interfacial pressure state of the cable accessories.