This paper presents the comparison study of wavenumber-based defect detection performance in full field laser scanning techniques. Two types of wave excitation are used for damage detection; guided waves and standing waves. A piezoelectric actuator is mounted on surface of the thin plate to generate guided and standing waves with a single excitation frequency. Subsequent responses on each grid point are measured using a Laser doppler vibrometer (LDV) with a mirror tilting device. Full field wave image is then generated from the measured wave signals. After the laser scanning, wavenumber based processing is applied to the measurements to generate two types of full wave field images and to detect structural damage. Three wavenumber based signal processing are applied to the wave filed images to estimate damage size and depth, including the Local wavenumber mapping, Acoustic Wavenumber Spectroscopy, 2D wavelet based wavenumber spectroscopy. For the comparison of these two techniques, several experiments are performed on thin walled structures with several different types of damage, including corrosion in an aluminum plate and debonding on composite plates. This paper outlines pros and cons of these two excitation techniques in terms of several parameters, including damage sensitivity, processing time and their applicability.
Jun Young Jeon, Duhwan Kim, Gyuhae Park, To Kang, and Soon Woo Han, "Comparison of guided and standing waves based full field laser scanning techniques for damage detection using wavenumber analysis (Conference Presentation)," Proc. SPIE 10602, Smart Structures and NDE for Industry 4.0, 106020K (Presented at SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring: March 06, 2018; Published: 3 April 2018); https://doi.org/10.1117/12.2296556.5763115402001.
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