An Experimental Platform for Electromagnetic Ultrasonic Guided Wave Tomography Technique

摘要

Electromagnetic ultrasonic guided wave tomography technique combines electromagnetic ultrasonic nondestructive testing with guided wave tomography technology, which can gain lots of visual information of defects in plates and improve the accuracy of testing. This paper presents an experimental platform which utilizes electromagnetic acoustic transducers to generate and receive Lamb wave and reconstructs the profile of defects of plate. This platform is significant for evaluating the design of electromagnetic acoustic transducers (EMATs) and various tomography algorithms. This experimental platform consists of transmitting and receiving circuits generating and receiving ultrasonic guided waves, data acquisition circuit collecting ultrasonic signal, FPGA circuits controlling the operation of the platform, a mechanical structure supporting test pieces, a motion module and positioning modules precisely detecting the positions of EMATs at different spatial sampling points. The working parameters of the platform are controlled by a laptop, and the received signals are displayed on the laptop as well. The software for the platform is developed based on LabWindows/CVI. A 2 mm thick aluminum plate with a blind hole with a diameter of 26 mm and a depth of 1 mm is scanned by the platform. The blind hole is reconstructed using tomography technique, which validates the effectiveness of the platform.