Title: Defect detection in thin plates by ultrasonic lamb wave techniques

Authors: K. Edalati, A. Kermani, M. Seiedi, A. Movafeghi

Addresses: Dept of NDT, Radiation Protection Technological Centre of Iran, North Kargar Street, P.O. Box: 14155-1399, Tehran, Islamic Republic of Iran. ' Dept of NDT, Radiation Protection Technological Centre of Iran, North Kargar Street, P.O. Box: 14155-1399, Tehran, Islamic Republic of Iran. ' Dept of NDT, Radiation Protection Technological Centre of Iran, North Kargar Street, P.O. Box: 14155-1399, Tehran, Islamic Republic of Iran. ' Dept of NDT, Radiation Protection Technological Centre of Iran, North Kargar Street, P.O. Box: 14155-1399, Tehran, Islamic Republic of Iran

Abstract: In the present study, the ability of ultrasonic lamb wave testing for defect detection and sizing in a thin aluminium plate (2mm in thickness) was investigated. The numerical methods were applied for drawing the dispersion and displacement curves of lamb waves in order to adopt mode selection. Two ultrasonic lamb wave techniques, pulse-echo (a1 mode as emitter) and emission (s1 mode as emitter), were applied for interpretation of notch defects with depths of 10, 30 and 60% of plate thickness. It was observed that these techniques are sensitive enough to evaluate notch defects, especially in short probe to defect distances. Defect location and defect length were proposed to be determined in the manner similar to common ultrasonic testing methods. Also, a Distance-Amplitude-Correction (DAC) curve was proposed for defect sizing which showed that amplitude analysis can give some qualitative information about defect depth but results were not always repeatable. The pulse-echo method showed better sensitivity for defect detection and sizing.

Keywords: defect sizing; dispersion; displacement; lamb wave; thin plates; defect detection; ultrasonic testing; non-destructive testing; NDT; aluminium plates; notch defects; amplitude analysis; pulse-echo.

DOI: 10.1504/IJMPT.2006.011268

International Journal of Materials and Product Technology, 2006 Vol.27 No.3/4, pp.156 - 172

Available online: 10 Nov 2006 *

Full-text access for editors Access for subscribers Purchase this article Comment on this article