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.

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 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.

A Non-Contact Guided Wave Technique for Defect Thinning Monitoring

2006 ◽  
Vol 326-328 ◽  
pp. 681-684 ◽  
Author(s):  
Ik Keun Park ◽  
Yong Kwon Kim ◽  
Tae Hyung Kim ◽  
Yong Sang Cho
Keyword(s):  
Guided Waves ◽  
Guided Wave ◽  
Velocity Change ◽  
Accelerated Corrosion ◽  
Ultrasonic Guided Wave ◽  
Acoustic Transducer ◽  
Thin Aluminum ◽  
Wave Technique ◽  
Electro Magnetic ◽  
Flow Accelerated Corrosion

This paper capitalizes on recent advances in the area of non-contact ultrasonic guided wave techniques. The present technique provides a decent method for nondestructive testing of defect thinning simulating a hidden corrosion or FAC(Flow Accelerated Corrosion) in a thin aluminum plate. The proposed approach is based on using EMAT(Electro-magnetic Acoustic Transducer) to generate guided waves and detect the wall thinning without any coupling. Interesting features in the dispersive behavior of selected guided modes are used for the detection of plate thinning. It is shown that mode cut-off measurement allows us to monitor a defect thinning level while a group velocity change can be used to quantify the thinning depth.

Evaluation of Notches in Pipes through the Use of Guided Wave and the Reflection Coefficient Method

2014 ◽  
Vol 614 ◽  
pp. 299-303
Author(s):  
Hai Quan Geng ◽  
Yue Min Wang ◽  
Long Xiang Zhu ◽  
Le Chen
Keyword(s):  
Reflection Coefficient ◽  
Guided Waves ◽  
Guided Wave ◽  
Quantitative Detection ◽  
Ultrasonic Guided Wave ◽  
Detection Technology ◽  
Experiment Method ◽  
Testing Technology ◽  
Defects Quantification ◽  
Coefficient Method

Ultrasonic guided wave quantitative detection technology has not been widely studied; this limits the application and development of guided waves testing technology greatly. For the quantitative detection study of notches in pipes, the theoretical model of guided waves interacted with notches has been built. Through the model, the relation formula between reflection coefficient and defects axial length and depth has been derived. The relation curves have been plotted based on the relation formula. And then, experiment method was used to verify the curves, the two methods can agree with each other. At last, the size of the defect was evaluated through the theoretical relation curves, the evaluation agrees with the practical size relatively. The research results provide necessary guide in theory to the defects quantification of guided wave detection.

Ultrasonic Guided Waves in Thin Orthotropic Layers: Exact and Approximate Analyses

2000 ◽  
Author(s):  
Subhendu K. Datta ◽  
Osama Mukdadi
Keyword(s):  
Wave Propagation ◽  
Exact Solutions ◽  
Elastic Constants ◽  
Guided Waves ◽  
Guided Wave ◽  
Thin Layers ◽  
Thin Plates ◽  
Low Frequencies ◽  
Ultrasonic Guided Wave ◽  
Guided Wave Propagation

Abstract Exact and approximate analyses of ultrasonic guided wave propagation in thin orthotropic layers are presented in this work. Exact solutions to the equations governing the dependence of guided wave propagation speeds on the elastic constants characterizing the anisotropic properties of the layers are presented and compared with the predictions of first order approximate theories for extensional and flexural waves in thin plates. Comparison with available experimental results for dispersion of these waves in thin sheets of different types of papers leads to the confirmation or modification of the elastic constants and density reported for these papers. A particular focus of this study is the coupling of three types of guided waves (extensional (S), flexural (A), and shear-horizontal (SH)) due to anisotropy of the material. It is shown that there are significant changes in the dispersion characteristics of these modes at certain frequencies, which can be exploited to measure the in-plane elastic properties of thin layers. Another focus is to study the limitations of approximate results when compared with exact solutions for wave propagation in different directions. In general good agreements are found at low frequencies.

Electromagnetic Acoustic Transducer (EMAT) Development for Nondestructive Inspection of Spent Nuclear Fuel Storage Canisters

2017 ◽  
Author(s):  
H. Cho ◽  
S. Choi ◽  
C. J. Lissenden ◽  
M. S. Lindsey
Keyword(s):  
Stainless Steel ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Nondestructive Inspection ◽  
Guided Wave ◽  
304 Stainless Steel ◽  
Electromagnetic Acoustic Transducer ◽  
Ultrasonic Guided Wave ◽  
Acoustic Transducer ◽  
Fuel Storage

Stress corrosion cracking (SCC) is a potential degradation mode that could undermine the long-term integrity of stainless steel canisters for spent nuclear fuel storage. Due to limited accessibility and harsh environments, ultrasonic nondestructive inspection for the canisters demands robot deliverable and environmentally tolerant transducers. Development of electromagnetic acoustic transducers (EMATs) for remote ultrasonic guided wave SCC inspection of stainless steel canisters is described. These noncontact EMATs use transduction based on the Lorentz force. Among the infinite possibilities of guided wave modes and frequencies to select from, shear horizontal (SH) waves are chosen due to their favorable sensitivity to cracks oriented both parallel and perpendicular to the wave vector. The EMAT components (i.e., magnets, electrical coils, connectors, casing, and cables) are carefully selected and tested under high temperature and gamma radiation dosage. The performance of the constructed compact EMATs is evaluated by experiments on a 304 stainless steel plate containing machined notches. Specifically, the distances from which the EMATs can detect surface-breaking defects of minimal size are determined.

Inspection of illumination pillar using ultrasonic guided wave by electromagnetic acoustic transducer

2019 ◽  
Vol 59 (4) ◽  
pp. 1487-1493
Author(s):  
Hiroyuki Nakamoto ◽  
Daichi Nakamura ◽  
Fumio Kojima ◽  
Keiichi Komatsu ◽  
Hideaki Tomita
Keyword(s):  
Guided Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Ultrasonic Guided Wave ◽  
Acoustic Transducer

Ultrasonic unilateral double-position excitation lamb wave defect detection and quantification method for ground electrode of transmission tower

2021 ◽  
pp. 1-15
Author(s):  
Kuan Ye ◽  
Kai Zhou ◽  
Ren Zhigang ◽  
Ruizhe Zhang ◽  
Chunsheng Li ◽  
...  
Keyword(s):  
Guided Waves ◽  
Power Transmission ◽  
Geometric Model ◽  
Guided Wave ◽  
Quantization Error ◽  
Dispersion Function ◽  
Stable Operation ◽  
Transmission Tower ◽  
Ultrasonic Guided Wave ◽  
Transmission Towers

The power transmission tower’s ground electrode defect will affect its normal current dispersion function and threaten the power system’s safe and stable operation and even personal safety. Aiming at the problem that the buried grounding grid is difficult to be detected, this paper proposes a method for identifying the ground electrode defects of transmission towers based on single-side multi-point excited ultrasonic guided waves. The geometric model, ultrasonic excitation model, and physical model are established, and the feasibility of ultrasonic guided wave detection is verified through the simulation and experiment. In actual inspection, it is equally important to determine the specific location of the defect. Therefore, a multi-point excitation method is proposed to determine the defect’s actual position by combining the ultrasonic guided wave signals at different excitation positions. Besides, the precise quantification of flat steel grounding electrode defects is achieved through the feature extraction-neural network method. Field test results show that, compared with the commercial double-sided excitation transducer, the single-sided excitation transducer proposed in this paper has a lower defect quantization error in defect quantification. The average quantization error is reduced by approximately 76%.

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