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 High Temperature Shear Horizontal Electromagnetic Acoustic Transducer for Guided Wave Inspection

Sensors ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 582 ◽  
Author(s):  
Maria Kogia ◽  
Tat-Hean Gan ◽  
Wamadeva Balachandran ◽  
Makis Livadas ◽  
Vassilios Kappatos ◽  
...  
Keyword(s):  
High Temperature ◽  
Guided Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Temperature Shear ◽  
Shear Horizontal

Flaw Detection in Aluminum Plate by Shear Horizontal Guided Wave Based on Magnetostriction EMAT

2014 ◽  
Vol 614 ◽  
pp. 287-290
Author(s):  
Le Chen ◽  
Yue Min Wang ◽  
Hai Quan Geng
Keyword(s):  
Guided Waves ◽  
Flaw Detection ◽  
Test Sample ◽  
Guided Wave ◽  
Sh Waves ◽  
Electromagnetic Acoustic Transducers ◽  
Acoustic Transducers ◽  
Non Destructive ◽  
Viable Method ◽  
Shear Horizontal

Shear horizontal (SH) guided waves have been proved to be a viable method in the Non-Destructive Evaluation (NDE). Electromagnetic acoustic transducers (EMAT) can excite SH waves easily. By bonding the Fe-Co alloy to the test sample, the SH guided waves based on magnetostriction effect can be used to detect the flaw in nonferromagnetic material. The principle of exciting and receiving SH waves is introduced, and an experiment is carried out to validate the result.

scholarly journals Nondestructive Inspection of Corrosion and Delamination at the Concrete-Steel Reinforcement Interface

2002 ◽  
Author(s):  
Tri Miller ◽  
Christopher J. Hauser ◽  
Tribikram Kundu
Keyword(s):  
Guided Waves ◽  
Guided Wave ◽  
Ultrasonic Guided Waves ◽  
Reinforcing Steel ◽  
Electromagnetic Acoustic Transducer ◽  
Long Distance ◽  
Steel Bar ◽  
Acoustic Transducer ◽  
Steel Bars ◽  
Aging Infrastructure

This paper explores the feasibility of detecting and quantifying corrosion and delamination at the interface between reinforcing steel bar and concrete using ultrasonic guided waves. The problem of corrosion and delamination of the reinforcing steel in the aging infrastructure has increased significantly in the last three decades and is likely to keep on increasing. Ultrasonic cylindrical guided waves that can propagate a long distance along the reinforcing steel bar are found to be sensitive to the interface conditions between steel bar and concrete. Ultrasonic transducers are used to launch and detect cylindrical guided waves along the steel bar. The traditional ultrasonic testing methods, for instance the pulse-echo method, where reflection, transmission, and scattering of longitudinal waves are used for detecting large voids in concrete, are not very efficient for detecting corrosion and delamination at the interface between concrete and steel bar. For this study four sets of specimens were prepared. They are rebars and plain steel bars with corrosion and physical separation. Transducers used during the experiment are the Electromagnetic Acoustic Transducer (EMAT) and the Piezoelectric Transducer (PZT). The experiment suggests that the guided wave inspection technique is feasible for the health monitoring of reinforced concrete structures. It also reveals that the ultrasonic guided waves are sensitive to the type of steel used and to the rib patterns on the reformed steel bars.

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.

Study on Dispersion Characteristics of Ultrasonic Guided Wave

2013 ◽  
Vol 333-335 ◽  
pp. 1713-1718
Author(s):  
Song Song Li ◽  
Xiao Ming Chen ◽  
Xiang Li
Keyword(s):  
Nondestructive Testing ◽  
Guided Waves ◽  
Guided Wave ◽  
Simulation Software ◽  
Dispersion Characteristics ◽  
Electromagnetic Acoustic Transducer ◽  
Low Frequencies ◽  
Ultrasonic Guided Wave ◽  
Acoustic Transducer ◽  
Testing Technology

Electromagnetic ultrasonic nondestructive testing technology, which it have the advantages of withstand high temperature and without coupling agent,is widely used in Nondestructive Testing (NDT) field. To effectively detect the defects, the dispersion characteristics and multimode of guided waves in the plate are studied by the disperse simulation software, and the variation of dispersion curve is analyzed by the geometric parameters and materials of plate. The results showed that the dispersion characteristics of guided wave in the plate is depended on the thickness and material of plate, and dispersion and the multimode characteristics of plate are better at low frequencies and smaller thickness. This is helpful to selection of Electromagnetic acoustic transducer (EMAT) parameter and detection operating point of guided wave.

Detection of Defects in Titanium Using Shear Horizontal Guided Waves

2021 ◽  
Author(s):  
Christian Peyton ◽  
Rachel S. Edwards ◽  
Steve Dixon ◽  
Ben Dutton ◽  
Wilson Vesga
Keyword(s):  
Guided Waves ◽  
Wave Mode ◽  
Guided Wave ◽  
Inspection System ◽  
Wave Direction ◽  
Finite Element Software ◽  
Small Defect ◽  
Back Face ◽  
The Relationship ◽  
Shear Horizontal

Abstract This paper investigates the interaction behaviour between the fundamental shear horizontal guided wave mode and small defects, in order to understand and develop an improved inspection system for titanium samples. In this work, an extensive range of defect sizes have been simulated using finite element software. The SH0 reflection from a defect has been shown previously to depend on its length as the total reflection consists of reflections from both the front and back face. However, for small defect widths, this work has found that the width also affects this interference, changing the length at which the reflection is largest. In addition, the paper looks at how the size of the defect affects the mode converted S0 reflection and SH0 diffraction. The relationship between the SH0 diffraction and defect size is shown to be more complex compared to the reflections. The mode converted S0 reflection occurs at an angle to the incident wave direction; therefore, the most suitable angle for the detection has been found. Simultaneous measurement of multiple waves would bring benefits to inspection.

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