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Proceedings Paper

Detection of cracks at rivet holes in thin plates using Lamb-wave scanning
Author(s): Roberto A. Osegueda; Vladik Kreinovich; Soheil Nazarian; Enrique Roldan
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Paper Abstract

This paper describes a Lamb-wave scanning method for the detection of notches simulating cracks at rivet holes in thin plates. The approach requires the generation of an ultrasonic So-Mode Lamb wave using an incident transmitter excited with a tone burst centered at a near non-dispersive frequency. Area scans are performed on a plate with a hole with a notch to generate times series information which is used to create animations illustrating the wave propagation characteristics. The time series are subject to a sifting process to obtain intrinsic mode functions which contain narrow frequency banded information of the signals. The Hilbert-Huang transform is applied to the intrinsic mode functions which permit the computation of the signal energy as a function of time, proportional to the square of the amplitude of the analytical signal. Animations of the propagation of the Lamb-wave energy illustrate that a potential scanning approach is to acquire time series along a line between the transmitter and the hole, capturing wave scattering from the hole and reflections from the notches. The times of flight and amplitudes of the notch-reflected energy are used to calculate coordinates of the source of the reflections by a geometric approach. The identified coordinates of the reflections outline the extent of the notch at the rivet hole. Results of experiments conducted on thin square plates with a single hole with notches of various sizes compare favorably with the actual notches.

Paper Details

Date Published: 1 August 2003
PDF: 12 pages
Proc. SPIE 5047, Smart Nondestructive Evaluation and Health Monitoring of Structural and Biological Systems II, (1 August 2003); doi: 10.1117/12.483969
Show Author Affiliations
Roberto A. Osegueda, Univ. of Texas at El Paso (United States)
Vladik Kreinovich, Univ. of Texas at El Paso (United States)
Soheil Nazarian, Univ. of Texas at El Paso (United States)
Enrique Roldan, Univ. of Texas at El Paso (United States)


Published in SPIE Proceedings Vol. 5047:
Smart Nondestructive Evaluation and Health Monitoring of Structural and Biological Systems II
Tribikram Kundu, Editor(s)

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