Shear horizontal circumferential wave EMAT design for pipeline inspection based on FEM

2020 ◽  
Vol 64 (1-4) ◽  
pp. 913-919
Author(s):  
Xu Zhang ◽  
Jiang Cheng ◽  
Gongzhe Qiu ◽  
Jun Tu ◽  
XiaoChun Song ◽  
...  
Keyword(s):  
Finite Element ◽  
Piezoelectric Transducer ◽  
Guided Waves ◽  
Element Model ◽  
Transduction Efficiency ◽  
Electromagnetic Acoustic Transducer ◽  
Pipeline Inspection ◽  
Acoustic Transducer ◽  
Circumferential Wave ◽  
Shear Horizontal

The electromagnetic acoustic transducer (EMAT) is widely used in In-Line Inspection of gas pipeline. However, the transduction efficiency of the EMAT transmitter is lower compared with the traditional piezoelectric transducer and needs improving. To enhance the amplitude of the received signal, an improved periodic-permanent-magnet EMAT is provided as well as its construction method to generate shear horizontal guided waves propagating in the circumferential direction. By designing a racetrack coil and magnetic array with the same radian of the annular pipeline, the EMAT is more suitable to generate the circumferential wave in the pipeline. The performance of the EMAT transmitter has been assessed with the validated finite element model.

Oil-Tank Weld Detection Using EMAT

2017 ◽  
Vol 14 (02) ◽  
pp. 1750008 ◽  
Author(s):  
Li Chen ◽  
Wang-Rim Choi ◽  
Jeong-Gu Lee ◽  
Yi-Gon Kim ◽  
Hong-Sik Moon ◽  
...  
Keyword(s):  
Elastic Waves ◽  
Guided Waves ◽  
Ferromagnetic Material ◽  
Transduction Efficiency ◽  
Sh Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Oil Tank ◽  
Non Destructive ◽  
Shear Horizontal

Tanks are typically used for the storage of oil by the petrochemical industry, and the storage quality is largely determined by the safety of the equipment. Recently, Electromagnetic Acoustic Transducer (EMAT) technology has been the focus of many non-destructive examinations, as EMATs can generate elastic waves without contact, thereby making it easy to carry out the process of detection. The Shear Horizontal (SH)-guided waves that are generated by an EMAT are modeled in a plate made of ferromagnetic material, and this is of particular interest regarding the testing of welded structures. This paper provides an EMAT-sensor design that can be used to find cracks in the welds of a tank whereby the need for people to climb onto the tank is removed; furthermore, regarding cases where the amplitude signal of the SH-wave EMATs is too low, a simulation is used in this paper to propose a method that improves the transduction efficiency.

An improved design of shear horizontal guided wave electromagnetic acoustic transducer

2020 ◽  
Vol 62 (8) ◽  
pp. 494-497
Author(s):  
Xu Zhang ◽  
Sheng Feng ◽  
Jun Tu ◽  
Xiaochun Song
Keyword(s):  
Guided Waves ◽  
Cost Effective ◽  
Guided Wave ◽  
Experimental Investigations ◽  
Electromagnetic Acoustic Transducer ◽  
Rectangular Array ◽  
Acoustic Transducers ◽  
Acoustic Transducer ◽  
Improved Design ◽  
Shear Horizontal

This work proposes the use of a Halbach magnet structure to enhance the generation efficiency of shear horizontal (SH) guided waves on a plate. SH waves are normally generated using periodic permanent magnet (PPM) electromagnetic acoustic transducers (EMATs). Two PPM configurations are designed using a Halbach magnet array and the enhancements of the static magnetic fields of the two magnet arrays are validated by the finite element method, indicating that these configurations can increase the peak flux density compared with the conventional configuration. Numerical analysis and experimental investigations indicate that a racetrack coil combined with either a rectangular or triangular Halbach magnet array can enhance the amplitude of the SH guided wave by factors of ∼1.2 and ∼1.1, respectively, and that the rectangular array performs better and is more cost effective.

scholarly journals Electromagnetic Acoustic Transducer (EMAT) sebagai Transduser Ultrasonik untuk Nondestructive Testing (NDT): Ulasan Artikel

2021 ◽  
Vol 13 (1) ◽  
pp. 1-14
Author(s):  
Keyword(s):  
Nondestructive Testing ◽  
Piezoelectric Transducer ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Shear Horizontal

Nondestructive testing (NDT) digunakan untuk mendeteksi keberadaan cacat pada suatu objek tanpa merusak objek tersebut, sehingga ideal untuk digunakan pada komponen-komponen infrastruktur yang sudah terpasang dan beroperasi. Diantara berbagai teknik, NDT ultrasonik memiliki kemampuan untuk menginspeksi cacat di sepanjang ketebalan objek, tidak hanya cacat permukaan. Metode pembangkitan gelombang ultrasonik yang paling populer adalah menggunaan piezoelectric transducer (PZT). Transduser ini memiliki efisiensi yang tinggi tetapi merupakan transduser kontak dan memerlukan pelumas (couplant), yang sering menyebabkan keterbatasan fleksibilitas untuk aplikasinya. Electromagnetic acoustic transducer (EMAT) adalah transduser ultrasonik yang dapat membangkitkan gelombang ultrasonik pada objek konduktif secara non-kontak. Transduser ini membangkitkan gelombang ultrasonik langsung pada objek uji, sehingga tidak memerlukan couplant. Hal ini menyebabkan EMAT ideal untuk inspeksi pada temperatur tinggi dimana couplant akan meleleh, dan pengujian yang bergerak. Dua jenis EMAT dibahas pada ulasan artikel ini: untuk membangkitkan gelombang shear horizontal (SH) dan gelombang torsional. Kedua jenis gelombang ini memiliki kelebihan dibanding moda gelombang lainnya, tetapi sulit untuk dibangkitkan menggunakan PZT. Kedua moda gelombang ini kemudian digunakan untuk menginspeksi penipisan pada pelat dan dinding pipa, yang dapat disebabkan oleh korosi maupun kontak mekanik. Hasil penelitian menunjukkan potensi EMAT dengan metoda konversi moda untuk inspeksi kuantitatif penipisan pada pelat dan pipa.

scholarly journals Electromagnetic Acoustic Transducer (EMAT) sebagai Transduser Ultrasonik untuk Nondestructive Testing (NDT): Ulasan Artikel

2021 ◽  
Vol 13 (1) ◽  
pp. 1-14
Author(s):  
Nurmalia Nurmalia ◽  
Keyword(s):  
Nondestructive Testing ◽  
Piezoelectric Transducer ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Shear Horizontal

Nondestructive testing (NDT) digunakan untuk mendeteksi keberadaan cacat pada suatu objek tanpa merusak objek tersebut, sehingga ideal untuk digunakan pada komponen-komponen infrastruktur yang sudah terpasang dan beroperasi. Diantara berbagai teknik, NDT ultrasonik memiliki kemampuan untuk menginspeksi cacat di sepanjang ketebalan objek, tidak hanya cacat permukaan. Metode pembangkitan gelombang ultrasonik yang paling populer adalah menggunaan piezoelectric transducer (PZT). Transduser ini memiliki efisiensi yang tinggi tetapi merupakan transduser kontak dan memerlukan pelumas (couplant), yang sering menyebabkan keterbatasan fleksibilitas untuk aplikasinya. Electromagnetic acoustic transducer (EMAT) adalah transduser ultrasonik yang dapat membangkitkan gelombang ultrasonik pada objek konduktif secara non-kontak. Transduser ini membangkitkan gelombang ultrasonik langsung pada objek uji, sehingga tidak memerlukan couplant. Hal ini menyebabkan EMAT ideal untuk inspeksi pada temperatur tinggi dimana couplant akan meleleh, dan pengujian yang bergerak. Dua jenis EMAT dibahas pada ulasan artikel ini: untuk membangkitkan gelombang shear horizontal (SH) dan gelombang torsional. Kedua jenis gelombang ini memiliki kelebihan dibanding moda gelombang lainnya, tetapi sulit untuk dibangkitkan menggunakan PZT. Kedua moda gelombang ini kemudian digunakan untuk menginspeksi penipisan pada pelat dan dinding pipa, yang dapat disebabkan oleh korosi maupun kontak mekanik. Hasil penelitian menunjukkan potensi EMAT dengan metoda konversi moda untuk inspeksi kuantitatif penipisan pada pelat dan pipa.

Circumferential and Spiral Waves in Piezoelectric Cylinders

2012 ◽  
Vol 622-623 ◽  
pp. 142-146 ◽  
Author(s):  
Ibrahim Muhammad ◽  
Hao Bai
Keyword(s):  
Finite Element ◽  
Eigenvalue Problem ◽  
Boundary Conditions ◽  
Guided Waves ◽  
Wave Spectrum ◽  
Spiral Wave ◽  
Element Model ◽  
Spiral Waves ◽  
Wave Number ◽  
Circumferential Wave

Study of the guided waves in piezoelectric cylinders based on a semi-analytical finite element method is presented. In the study, the dispersion equation was formulated as a generalized eigenvalue problem by treating mechanical displacements and electric potential with one dimensional quadratic finite element model through the thickness of the cylinder. Here the general eigenvalue problem is depended on three parameters, namely, the frequency, the axial wave number and the circumferential wave. A non-integer circumferential wave is introduced here for studying the guided spiral wave. A wave spectrum surface is generated to incorporate the guided spiral waves. Cylinders having different geometry and electric boundary conditions are studied but only the results for a thin cylinder with closed electric boundary conditions are presented.

Contribution of Lamb wave modes in the formation of higher order modes cluster (HOMC) guided waves

2021 ◽  
pp. 095440622110424
Author(s):  
Z Abbasi ◽  
F Honarvar
Keyword(s):  
Finite Element ◽  
Wave Packet ◽  
Lamb Wave ◽  
Guided Waves ◽  
Element Model ◽  
Higher Order ◽  
Guided Wave ◽  
Cross Sectional ◽  
Higher Order Modes ◽  
Wave Modes

In recent years, Higher Order Modes Cluster (HOMC) guided waves have been considered for ultrasonic testing of plates and pipes. HOMC guided waves consist of higher order Lamb wave modes that travel together as a single nondispersive wave packet. The objective of this paper is to investigate the effect of frequency-thickness value on the contribution of Lamb wave modes in an HOMC guided wave. This is an important issue that has not been thoroughly investigated before. The contribution of each Lamb wave mode in an HOMC guided wave is studied by using a two-dimensional finite element model. The level of contribution of various Lamb wave modes to the wave cluster is verified by using a 2D FFT analysis. The results show that by increasing the frequency-thickness value, the order of contributing modes in the HOMC wave packet increases. The number of modes that comprise a cluster also increases up to a specific frequency-thickness value and then it starts to decrease. Plotting of the cross-sectional displacement patterns along the HOMC guided wave paths confirms the shifting of dominant modes from lower to higher order modes with increase of frequency-thickness value. Experimental measurements conducted on a mild steel plate are used to verify the finite element simulations. The experimental results are found to be in good agreement with simulations and confirm the changes observed in the level of contribution of Lamb wave modes in a wave cluster by changing the frequency-thickness value.

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