Determination of dispersion curves of higher order guided ultrasonic waves based on experimental data by a 2D-DFT

• Published in: E-journal of Nondestructive Testing Vol. 29; no. 7
• Main Authors: Barth, Tilmann, Rauter, Natalie
• Format: Journal Article
• Language: English
• Published: 01.07.2024
• DOI: 10.58286/29770
• ISSN: 1435-4934

Guided ultrasonic wave based structural health monitoring has been subject to research over the last decades. In order to analyze the wave propagation data correctly, knowledge about the fundamental wave propagation properties is indispensable. Due to the multimodal and dispersive nature of guided ultrasonic waves these properties are characterized by dispersion diagrams. In previous work by the authors [1] the dispersion behavior of the guided ultrasonic waves is extracted by an adapted non-uniform 2D-DFT algorithm based on [2]. With this algorithm the dispersion curves can be computed from experimental data in an accurate and highly automated fashion. So far the application is limited to the fundamental wave modes over large frequency ranges. In this work the approach is extended to higher-order wave modes, which are of special interest in particular for the nonlinear wave propagation. To analyze the robustness of the presented data acquisition algorithm the procedure is applied first to isotropic waveguides and second to more complex material systems like fiber metal laminates. The results indicate that the presented approach enables one to derive the dispersion curves over large frequency ranges from experimental data not only for the fundamental A0 and S0 wave modes but also for higher-order modes. References [1] Barth T, Rauter N and Lammering R. Experimental determination of Lamb wave dispersion diagrams using 2d fourier transform and laser vibrometry. Preprint at https://wwwresearchsquarecom/article/rs-1321459/v1 2022; 10.21203/rs.3.rs-1321459/v1. [2] Alleyne DN. The nondestructive testing of plates using ultrasonic Lamb waves. PhD Thesis, Imperial College of Science, Technology and Medicine, London, 1991.