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Calculation of the dispersion curves modeling the propagation of ultrasonic Lamb waves in a bonded aluminum/epoxy/aluminum structure using the semi-analytical finite element method

Azkour Mustapha, Allami Mhammed El, Rhimini Hassan

Engineering Transactions

2024

Vol. 72, iss. 2

119--143

The main aim of this paper is to calculate the dispersion curves modeling the propagation of ultrasonic Lamb waves inside a bonded tri-layer plane aluminum/epoxy/aluminum structure using the semi-analytical finite element (SAFE) method. The paper also aims to plot the nodal displacements normalized by their maximums for the four propagative modes that appear at the frequency of 200 kHz. These results contribute to the understanding of ultrasonic wave propagation in planar multilayer structures and have potential applications in non-destructive testing. The SAFE method is compared to the Graphical User Interface for Guided Ultrasonic Waves GUIGUW program. In general, this paper highlights the particular dispersive behavior of ultrasonic guided waves propagating in bonded three-layer structures. The GUIGUW program has been rarely utilized by authors to verify and compare results, particularly for this kind of structure, despite its robustness in calculating ultrasonic guided waves’ dispersion curves. We are still among the few who have drawn this parallel. In this paper, we put forth a very clear-cut and accurate framework for determining the dispersion curves of a three-layer structure, and researchers who are new to the SAFE method may find this framework helpful as well. Another result shown in this paper is that the S0 mode is more sensitive to changes in the epoxy layer thickness than the A0 mode in the low-frequency range. Therefore, we can determine how much resin epoxy adhesive layer is missing from two ostensibly identical structures by estimating the difference in adhesive thickness. One of the structures is used as a reference, and the variation in phase velocity can allow the estimation of the lack of resin epoxy. However, if we want to assess defects such as debonding using the S0 mode, a low frequency should be used, and it must be strictly smaller than its frequency of high dispersivity and correspond to a maximum group velocity.

Removal of Fouling from Steel Plate Surfaces Based on Multi-Frequency Eco-Friendly Ultrasonic Guided Wave Technology

Huang Mingkun, Jin Shuo, Nie Gaoqian, Wang Xiaopeng, Zhang Quanpeng, An Yang, Qu Zhigang, Yin Wuliang

Archives of Acoustics

2023

Vol. 48, No. 4

593--601

Fouling is inevitable on the surfaces of industrial equipment, especially on heat-exchanging surfaces in contact with fluids, which causes water pollution and destroys the ecological environment. In this paper, a novel fouling-removal methodology for plate structure based on cavitation by multi-frequency ultrasonic guided waves is proposed, which can remove fouling on stainless steel plates. A numerical simulation method has been developed to study the acoustic pressure distribution on a steel plate. According to the simulation results, the distribution of sound pressure on the plate under triple-frequency excitation is denser and more prone to cavitation than in single-frequency cases and dual-frequency cases, which improves fouling removal rate. The stainless steel plate is immersed in water for the descaling experiment, and the results show that the fouling removal rates of three water-loaded stainless steel plates under different single-frequency excitation seem unsatisfactory. However, the multi-frequency excitation improves the descaling performance and the removal rate of fouling reaches 80%. This new method can be applied to the surface descaling of large equipment plates, which is of great significance for purifying water quality and protecting the ecological environment.

Badanie kotew kopalnianych przy użyciu fal prowadzonych

Stepiński Tadeusz

Badania Nieniszczące i Diagnostyka

2020

nr 1-4

18--27

W artykule przedstawiono metodę badania kotew górniczych przy użyciu fal ultradźwiękowych. Na wstępie zaprezentowano kilka specjalistycznych czujników i instrumentów, które można wykorzystać do monitorowania kotew w czasie ich eksploatacji. Artykuł koncentruje się na zastosowaniu do badań prowadzonych fal ultradźwiękowych zdolnych do rozprzestrzeniania się na duże odległości w prętach. Fale te są jednak dyspersyjne i multimodalne, co oznacza, że wiele postaci falowych może propagować jednocześnie z różnymi prędkościami zależnymi od częstotliwości. Zastosowanie ultradźwiękowych fal do kotew NDE omówione szczegółowo na przykładzie instrumentu RBT (Rock-Bolt Tester), który jest cyfrowym instrumentem ultradźwiękowym pracującym w układzie puls-echo, wyposażonym w specjalnie skonstruowaną głowicę ultradźwiękową, zdolną do generowania fal sprężystych o wysokiej energii i niskiej częstotliwości (poniżej 100kHz). Głowica jest również zdolna do odbierania słabych ech odbitych od końca kotwy i od nieciągłości w zaprawie ją otaczającej. Echa odbierane przez sondę są wzmacniane, filtrowane i prezentowane graficznie w postaci A-skanów. Na zakończenie, dla ilustracji działania instrumentu RBT przedstawiono wyniki jego weryfikacji eksperymentalnej.

In this paper we are presenting principles of rock-bolts NDE using ultrasonic guided waves. A number of specialized sensors and instruments is presented that can be used for monitoring bolts status. The paper is focused on the application of ultrasonic guided waves (GW) able to propagate over long distances in bars. GWs are, however, dispersive and multimodal, which means that many wave modes can propagate simultaneously with different frequency dependent velocities. Application of ultrasonic guided waves for rock-bolts NDE is presented in some detail using for illustration the new designed instrument rock-bolt tester (RBT). RBT is a pulse-echo digital ultrasound instrument provided with an application tailored ultrasound probe that transmits high-energy, low frequency (below 100kHz) guided waves. The probe is also capable of receiving weak echoes reflected from the bolt-end and from some discontinuities in the surrounding grout. The echoes received by the probe are amplified, filtered and presented in the form of A-scans. Experimental results are presented that illustrate the performance of the RBT instrument.