Simulation-Based Analysis of Active Infrared Thermography for Detecting Internal Void Defects in Silicone Rubber

Silicone rubber (SIR), a commonly used polymer insulation material in power systems, requires timely detection of internal defects. Active infrared thermography (AIT) technology, as an emerging non-destructive testing technique, holds significant potential for detecting internal defects in SIR. In this paper, we conducted simulation research on the thermal wave propagation characteristics of internal air-filled defects in SIR. We systematically analyzed the relationship between thermal wave propagation features and the depth and size of defects in the time, space, and frequency domains. Firstly, from a time-domain perspective, we analyzed the temporal characteristics of thermal wave propagation, deriving the relationship between temperature during the cooling phase, temperature deviation time, and defect depth and size. Secondly, in the spatial dimension, we analyzed the defect outlines in thermal images and their relationship with defect depth and size. We also measured defect size using the full width at half maximum method and determined the relationship between measurement errors and defect information. Finally, we analyzed the relationship between defect size, depth, and frequency domain characteristics. This research work establishes a connection between thermal wave features and defect information, providing a theoretical basis for quantitatively measuring internal defects in SIR using AIT.