Application of a Non-Contact Laser Ultrasonic Imaging Technology for Detection Weld Defect Based on Hilbert Transform

摘要

A non-contact laser ultrasonic imaging technique was proposed to detect austenitic stainless steel weld with artificial defects. Austenitic stainless steel weld was scanned by a pulsed laser, and the ultrasonic waves were received by the interferometer. The vibration images of ultrasonic waves at different locations were analyzed in detail. In order to detect the size of the damage, we use the Hilbert transform method to transform ultrasonic time-domain signals into the envelope of ultrasonic wave, and find this method can improve the effects of detection the flaw. By comparing the propagation images based on the Hilbert transform method, with the result based on the anomalous wave propagation imaging method which demonstrated that the non-contact laser ultrasonic imaging technique based on the Hilbert transform method, we can evaluate the sizes of the weld damages. Hence, we proposed the ultrasonic propagation imaging approach for automatic inspection in manufacturing.