Actas de congresos
Technique to combine images produced by different propagation modes of guided waves for damage detection and contrast improvement in plate-like structures
Fecha
2012-12-01Registro en:
IEEE International Ultrasonics Symposium, IUS, p. 1441-1444.
1948-5719
1948-5727
10.1109/ULTSYM.2012.0360
2-s2.0-84882430610
6405339510883203
2883440351895167
0000-0003-4201-5617
0000-0001-6320-755X
Autor
Universidade Estadual Paulista (Unesp)
Consejo Superior de Investigaciones Cientficas
Universidade de São Paulo (USP)
Institución
Resumen
This paper describes an image compounding technique based on the use of different apodization functions, the evaluation of the signals phases and information from the interaction of different propagation modes of Lamb waves with defects for enhanced damage detection, resolution and contrast. A 16 elements linear array is attached to a 1 mm thickness isotropic aluminum plate with artificial defects. The array can excite the fundamental A0 and S0 modes at the frequencies of 100 kHz and 360 kHz, respectively. For each mode two synthetic aperture (SA) images with uniform and Blackman apodization and one image of Coherence Factor Map (CFM) are obtained. The specific interaction between each propagation mode and the defects and the characteristics of acoustic radiation patterns due to different apodization functions result in images with different resolution and contrast. From the phase information one of the SA images is selected at each pixel to compound the final image. The SA images are multiplied by the CFM image to improve contrast and for the dispersive A0 mode it is used a technique for dispersion compensation. There is a contrast improvement of 47.5 dB, reducing the dead zone and improving resolution and damage detection. © 2012 IEEE.