Thickness measurement of metal components using guided waves and fully non-contact PL-SLDV system

Andrew Campbell; Wenfeng Xiao; Kathryn Metzger; Jorie Walters; Lingyu Yu

doi:10.1117/12.3011174

9 May 2024 Thickness measurement of metal components using guided waves and fully non-contact PL-SLDV system

Andrew Campbell, Wenfeng Xiao, Kathryn Metzger, Jorie Walters, Lingyu Yu

Proceedings Volume 12951, Health Monitoring of Structural and Biological Systems XVIII; 129511A (2024) https://doi.org/10.1117/12.3011174
Event: SPIE Smart Structures + Nondestructive Evaluation, 2024, Long Beach, California, United States

Abstract

Effective NDE inspection systems and methods are highly desired in a broad range of engineering applications including metal structure thickness evaluation. Laser-generated ultrasound has been studied to excite wideband Lamb waves for NDE. By using the ultrasound in conjunction with multidimensional wavefield measurements, obtained by high spatial resolution noncontact laser scanning vibrometer, thickness evaluations for metal components can be achieved. This paper applies a fully noncontact/remote ultrasonic Lamb wave NDE system and explores its application for thickness characterization and evaluation of metal components. This paper first demonstrates the actuation and sensing of Lamb waves in metal components. The non-contact system consists of a Pulsed Laser (PL) working in the thermoelastic regime to excite Lamb waves and Scanning Laser Doppler vibrometer (SLDV) sensing the waves and providing high-resolution multidimensional wavefield signals for evaluation. Enhancements through sensing, actuation parameters, and surface enhancement were attempted to excite very high-frequency Lamb waves. The results show that excited Lamb waves can have a frequency beyond 1 MHz in certain components thinner than 1 mm. The paper continues to show how the acquired Lamb waves can be used for measuring the thickness of the metal components. The method adopted multidimensional Fourier analysis to convert time-space wavefield measurements to frequency-wavenumber representation. The resulting spectrum is then compared to theoretical dispersion curves in frequency-wavenumber for thickness matching to derive the thickness parameter. Proof-of-concept tests were performed with aluminum components of various thicknesses first and then the method was applied to much thinner foil-type material and components made of different materials.

Conference Presentation

Citation Download Citation

Andrew Campbell, Wenfeng Xiao, Kathryn Metzger, Jorie Walters, and Lingyu Yu "Thickness measurement of metal components using guided waves and fully non-contact PL-SLDV system", Proc. SPIE 12951, Health Monitoring of Structural and Biological Systems XVIII, 129511A (9 May 2024); https://doi.org/10.1117/12.3011174

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