Study On Defects Of Porcelain Insulators By Laser Ultrasonic Testing

The application for nondestructive detection of the porcelain insulator defects using laser ultrasonic by pulsed laser are studied in this thesis. The methods for on-line detection of the porcelain insulator and the theory of laser ultrasonic by pulsed laser on strut porcelain insulator are stated. The specificities for nondestructive detection of the porcelain insulator defects are analyzed. The methods for remote and non-contact nondestructive detection of the porcelain insulator defects using laser ultrasonic is proposed. The experimental platform of remote and non-contact nondestructive detection using laser ultrasonic was set up. The samples of the porcelain insulator with different defects are prepared. The visual results of a measurement are received by the experiment for visual and remote and non-contact nondestructive detection using laser ultrasonic for these samples.The distribution of transient temperature and displacement field for the porcelain insulator by laser ultrasonic irradiating are simulated using finite element numerical method under the thermo elastic mechanism. The results of numerical simulation show that the laser ultrasonic displacement signals by pulsed laser irradiation porcelain insulator are very weak, and the order of magnitude of the vibration of the particle displacement in nanometer, it offer necessary reference for selection of the nondestructive detection methods.In addition, according to the demand of on-line charged detection of porcelain insulator, the remote laser ultrasonic testing system has been built based on the laser ultrasonic visualization detector, the launch part and receiving part of the experimental platform are introduced in detail. According to the experimental requirements, the porcelain insulators with different defects were manufactured and collected, then make a quantitative description for them.The not fully contact and fully non-contact laser ultrasonic testing experimental platform based on laser ultrasonic visualization detector has been established, and the porcelain insulator samples with defects were manufactured for the experiment. Based on the not fully contact and fully non-contact laser ultrasonic visualization measurement of the laser ultrasonic visualization detector, the porcelain insulator samples with the artificial inclined groove, straight groove and defects were measured under laboratory conditions, and measurement results of visualization were obtained under the different detecting condition.