Non-destructive Testing Method for Composite Insulators Based on Digital Shearography

Abstract

Due to the special characteristics of materials, structures and manufacturing processes, composite insulators are prone to generate internal defects during the production process and on-site operations. In this paper, an internal defect detection method for composite insulators based on digital shearography is proposed to eliminate faulty insulators in production and during operation. This method diagnoses the defects of composite insulators and the severity by measuring surface abnormal deformation caused by internal defects. Compared with other non-destructive testing techniques, it has the characteristics of high speed, high accuracy, non-contact, and full-field imaging. Insulator samples with man-made defects were examined, and the defect information was quickly and intuitively detected by the interference fringe pattern and phase profile obtained. The feasibility of digital shearography for the detection of internal defects in composite insulators was verified by artificial defects detection experiments.