Application of Terahertz Technology in Delamination Defect Inspection for Vehicle High-Voltage Cable Terminals

The cable terminals are subjected to the combined action of transient overvoltage impact, rapid alternating cold and heat and long-term high-frequency vibration, resulting in the stratification of its internal insulation layer, micro air gap and partial discharge. Therefore, this paper studies the influence of delamination defect in vehicle high-voltage cable terminals on terahertz time-frequency domain. A three-layer composite structure is established to simulate the internal defects of vehicle high-voltage cable terminals. The results show that the THz absorption spectrum can be used to quickly judge whether there are defects, and the ability of absorbing terahertz wave in the area with insulation delamination is greater than that in the normal area. The location and geometric information of the defect can be roughly determined by multi-mode terahertz imaging of the sample with insulation delamination defect, and the imaged defect areas are verified by the area detection method based on image segmentation. Finally, the thickness of stress tube layers, air gaps and main insulation layers can be quickly estimated by terahertz time domain spectrum. Through Terahertz Absorption spectrum, terahertz multimode imaging and terahertz time domain spectrum, the internal delamination defects of vehicle high-voltage cable terminals can be comprehensively characterized.