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.

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 Pure SH1 Guided-Wave Generation Method with Dual Periodic-Permanent-Magnet Electromagnetic Acoustic Transducers for Plates Inspection

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 3019 ◽  
Author(s):  
Gongzhe Qiu ◽  
Xiaochun Song ◽  
Xu Zhang ◽  
Jun Tu ◽  
Tao Chen
Keyword(s):  
Permanent Magnet ◽  
Guided Waves ◽  
Simulation Analysis ◽  
Guided Wave ◽  
Enhancement Effect ◽  
Large Area ◽  
Suppression Effect ◽  
Electromagnetic Acoustic Transducers ◽  
Positioning Errors ◽  
Acoustic Transducers

High frequency guided-waves offer a trade-off between the high sensitivity of local bulk ultrasonic thickness measurements and the large area scanning of lower frequency guided-waves, so it has been a growing interest for corrosion inspection with the dispersive SH1 mode. However, according to the dispersive curve, it is hard to generate the pure SH1 mode since the non-dispersive SH0 mode will be excited simultaneously. Thus, this paper investigates a transducer design method to generate a pure SH1 guided-wave, where the dual periodic-permanent-magnet electromagnetic acoustic transducers (PPM EMATs) are placed on exactly opposite positions either side of the plate symmetrically. The suppression effect for SH0 and the enhancement effect for SH1 of the dual PPM EMATs are mainly discussed by theoretical analysis and simulation analysis, and the influence of positioning errors of PPM EMATs placed on opposite sides of the plate on its performances are analyzed. Employing the proposed dual PPM EMATs, some experiments are performed to verify the reliability of finite element simulation. The results indicate that the dual PPM EMATs can suppress the SH0 mode and generate the pure SH1 mode effectively. Moreover, the longitudinal and lateral positioning errors can affect the dual PPM EMATs performances significantly.

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.

Immunity of the second harmonic shear horizontal waves to adhesive nonlinearity for breathing crack detection

2021 ◽  
pp. 147592172110571
Author(s):  
Fuzhen Wen ◽  
Shengbo Shan ◽  
Li Cheng
Keyword(s):  
Crack Detection ◽  
Guided Waves ◽  
Lamb Waves ◽  
Second Harmonic ◽  
Sh Waves ◽  
High Order Harmonic ◽  
Thin Walled Structures ◽  
Harmonic Shear ◽  
Contact Acoustic Nonlinearity ◽  
Shear Horizontal

High-order harmonic guided waves are sensitive to micro-scale damage in thin-walled structures, thus, conducive to its early detection. In typical autonomous structural health monitoring (SHM) systems activated by surface-bonded piezoelectric wafer transducers, adhesive nonlinearity (AN) is a non-negligible adverse nonlinear source that can overwhelm the damage-induced nonlinear signals and jeopardize the diagnosis if not adequately mitigated. This paper first establishes that the second harmonic shear horizontal (second SH) waves are immune to AN while exhibiting strong sensitivity to cracks in a plate. Capitalizing on this feature, the feasibility of using second SH waves for crack detection is investigated. Finite element (FE) simulations are conducted to shed light on the physical mechanism governing the second SH wave generation and their interaction with the contact acoustic nonlinearity (CAN). Theoretical and numerical results are validated by experiments in which the level of the AN is tactically adjusted. Results show that the commonly used second harmonic S0 (second S0) mode Lamb waves are prone to AN variation. By contrast, the second SH0 waves show high robustness to the same degree of AN changes while preserving a reasonable sensitivity to breathing cracks, demonstrating their superiority for SHM applications.

Imaging and Testing of Ultrasonic Sh Guided Waves in Plate with Lap Welding Structure

2011 ◽  
Vol 301-303 ◽  
pp. 603-609
Author(s):  
Xin Jie Zhu ◽  
Zan Dong Han ◽  
Dong Du ◽  
Yi Fang Chen ◽  
Ke Yi Yuan
Keyword(s):  
Guided Waves ◽  
Experimental System ◽  
Destructive Testing ◽  
Long Distance ◽  
Testing Zone ◽  
Lap Welding ◽  
Corrosion Defects ◽  
Synthetic Aperture Focusing ◽  
Non Destructive ◽  
Shear Horizontal

The imaging and testing of ultrasonic SH (Shear Horizontal) guided waves may be used into testing and SHM (Structure Health Monitoring) of industrial plate with welding structure in service, which have much more important applied potential. During imaging and testing for steel plate with lap welding structure, photoelastic experiment on propagation of guided waves in Plexiglas plate was studied to clearly see the excellent advantages of SH guided waves. The mode of SH guided waves was analyzed to select the zero order mode SH0 and the SH guided waves transducer with SH0 mode was developed. Based on the synthetic aperture focusing method，a multichannel ultrasonic imaging and testing experimental system of ultrasonic SH guided waves was constructed，the imaging of plate with lap welding structure was mainly studied. The research results shows the ultrasonic SH guided waves and the transducers are fit for long distance testing for the plate with lap welding structure. The ultrasound scattering nearby the weld may cause a blind testing zone, about 150 mm wide, in which the less size corrosion defects at the blind zone could not be revealed in image, so as to lead to defects “no testing”. The imaging and testing of ultrasonic SH guided waves would be used for non-destructive testing of plate with lap welding structure, which image both can characterize the corrosion defects and lap welding structure, and realize the precise location of the weld. The proposed research provides important foundation for improving ultrasonic guided waves imaging and testing quality and SHM of industrial in-site plate with lap welding and larger size.

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