Evaluation of Hidden Corrosion in a Thin Plate Using a Non-Contact Guided Wave Technique

2006 ◽  
Vol 321-323 ◽  
pp. 492-496 ◽  
Author(s):  
Ik Keun Park ◽  
Tae Hyung Kim ◽  
Hyun Mook Kim ◽  
Yong Kwon Kim ◽  
Yong Sang Cho ◽  
...  
Keyword(s):  
Ultrasonic Wave ◽  
Thin Plate ◽  
Guided Waves ◽  
Wave Generation ◽  
Guided Wave ◽  
Thickness Reduction ◽  
Thin Plates ◽  
Depth Measurement ◽  
Mode Cutoff ◽  
Hidden Corrosion

In this paper, study on evaluation of thickness reduction in a thin plate with guided waves is presented. Ultrasonic guided wave techniques have been widely studied and successfully applied to various non-destructive tests with the advantage of long range inspection. In addition to application of guided waves to NDT, non-contact methods for ultrasonic wave generation and detection have become very useful and well combined with guided wave techniques due to their capability of ultrasonic wave generation and reception in surface of high temperature or on rough surface. An advanced non-contact technique for detection of thickness reduction simulating hidden corrosion in thin plates using guided waves is proposed. The proposed approach uses EMAT(Electro-Magnetic Acoustic Transducer) for the non-contact generation and detection of guided waves in aluminum plates. Interesting features of the dispersive behavior in selected wave modes are used to detect plate thinning. The experimental results show that the mode cutoff measurements provide a qualitative measurement of thinning detects and change in the mode group velocity can be used as quantitative parameter of thinning depth measurement.

Evaluation of Hidden Corrosion in a Thin Plate Using a Non-Contact Guided Wave Technique

2006 ◽  
pp. 492-496
Author(s):  
Ik Keun Park ◽  
Tae Hyung Kim ◽  
Hyun Mook Kim ◽  
Yong Kwon Kim ◽  
Yong Sang Cho ◽  
...  
Keyword(s):  
Thin Plate ◽  
Guided Wave ◽  
Wave Technique ◽  
Hidden Corrosion

scholarly journals Modeling Magnetostrictive Transducers for Structural Health Monitoring: Ultrasonic Guided Wave Generation and Reception

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7971
Author(s):  
Gaofeng Sha ◽  
Cliff J. Lissenden
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Guided Waves ◽  
Lamb Waves ◽  
Wave Mode ◽  
Wave Generation ◽  
Guided Wave ◽  
Diverse Range ◽  
Structural Health ◽  
Phase Velocity Dispersion

Ultrasonic guided waves provide unique capabilities for the structural health monitoring of plate-like structures. They can detect and locate various types of material degradation through the interaction of shear-horizontal (SH) waves and Lamb waves with the material. Magnetostrictive transducers (MSTs) can be used to generate and receive both SH and Lamb waves and yet their characteristics have not been thoroughly studied, certainly not on par with piezoelectric transducers. A series of multiphysics simulations of the MST/plate system is conducted to investigate the characteristics of MSTs that affect guided wave generation and reception. The results are presented in the vein of showing the flexibility that MSTs provide for guided waves in a diverse range of applications. In addition to studying characteristics of the MST components (i.e., the magnetostrictive layer, meander electric coil, and biased magnetic field), single-sided and double-sided MSTs are compared for preferential wave mode generation. The wave mode control principle is based on the activation line for phase velocity dispersion curves, whose slope is the wavelength, which is dictated by the meander coil spacing. A double-sided MST with in-phase signals preferentially excites symmetric SH and Lamb modes, while a double-sided MST with out-of-phase signals preferentially excites antisymmetric SH and Lamb modes. All attempted single-mode actuations with double-sided MSTs were successful, with the SH3 mode actuated at 922 kHz in a 6-mm-thick plate being the highest frequency. Additionally, the results show that increasing the number of turns in the meander coil enhances the sensitivity of the MST as a receiver and substantially reduces the frequency bandwidth.

A Non-Contact Ultrasonic Sensor for General Corrosion Inspection of Thin Plates

2018 ◽  
Author(s):  
Akinori Tamura ◽  
Masahiro Miki ◽  
Naoyuki Kono ◽  
Hiroshi Okazawa ◽  
Shinobu Okido ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Thin Plate ◽  
Power Plants ◽  
Guided Waves ◽  
Plate Thickness ◽  
Ultrasonic Sensor ◽  
Thin Plates ◽  
Inspection Time ◽  
General Corrosion ◽  
Feasibility Test

In power plants, there are structures made up of thin plates, such as air-conditioning ducts or thin-walled pipes, where corrosion can occur. In this study, we provide a solution to reduce inspection time of the thin plate corrosion measurement and enable monitoring, using a non-contact ultrasonic sensor. The sensor can measure the reduction in thickness of thin plates due to general corrosion without the need to remove or reinstall insulating material that is on the outside of the plate. The proposed sensor is based on the non-contact ultrasonic measurement technique which was originally proposed by Greve et al, further developed and patented by Zhong et al. at the University of Bristol, and commercialized by Inductosense Ltd. In order to ultrasonically measure the thin plate thickness, we use a method based on the group velocity of the guided waves. The proposed method was tested theoretically with numerical simulations and experimentally against our target conditions. The results of the numerical simulations and experiments confirm that the proposed method can be applied to thickness measurements of thin-plates in our target condition. Based on the feasibility test results, we developed a prototype sensor and measurement software. From the results of the performance evaluation tests, we have confirmed that the prototype sensor has sufficient capability to measure the thickness of the thin plates without the removal of the insulator. Even if the offset between the plate and the inspection probe is 100 mm, the prototype sensor still works well.

Application of Torsional Mode of Guided Waves to Long Range Pipe Inspection

2006 ◽  
Vol 326-328 ◽  
pp. 473-476
Author(s):  
Ik Keun Park ◽  
Yong Kwon Kim ◽  
Won Joon Song ◽  
Yong Sang Cho
Keyword(s):  
Long Range ◽  
Wall Thickness ◽  
Guided Waves ◽  
Guided Wave ◽  
Ultrasonic Guided Waves ◽  
Thickness Reduction ◽  
Torsional Mode ◽  
Pipeline Inspection ◽  
Cross Section Area ◽  
Section Area

Conventional non-destructive techniques for inspection of weld in pipelines require significant test time and high cost. In order to overcome these drawbacks in conventional NDT techniques, various techniques using ultrasonic guided waves have been developed and applied to the pipeline inspection. Recently, a fast calculation technique for guided wave propagation using a semi-analytical finite element method (SAFEM), PIPE WAVE ver.1.0, has been developed by T. Takahiro et al [1]. In this paper, the calculation of torsional mode propagation in a pipe using PIPE WAVE ver. 1.0 is introduced as a preliminary study and the application of the torsional mode of ultrasonic guided waves to long range pipe inspection is presented.. The characteristics and setup of a long range guided wave inspection system and experimental results in pipes of various diameters are introduced. The experimental results in mock-up pipes with cluster type detects show that the limit of detectable wall thickness reduction with this guided wave system is 2~3% in the pipe cross section area and the wall thickness reduction of 5% in cross section area can be detected when actual detection level is used. Therefore, the applicability of the ultrasonic guided wave technique to long range pipeline inspection for wall thickness reduction is verified.

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.

Stress evaluation in seven-wire strands based on singular value feature of ultrasonic guided waves

2021 ◽  
pp. 147592172110053
Author(s):  
Qian Ji ◽  
Li Jian-Bin ◽  
Liu Fan-Rui ◽  
Zhou Jian-Ting ◽  
Wang Xu
Keyword(s):  
Dispersion Curve ◽  
Support Vector Regression ◽  
Stress Level ◽  
Guided Waves ◽  
Guided Wave ◽  
Singular Value ◽  
Support Vector ◽  
Support Vector Regression Model ◽  
Various Boundary Conditions ◽  
Wave Methods

The seven-wire strands are the crucial components of prestressed structures, though their performance inevitably degrades with the passage of time. The ultrasonic guided wave methods have been intensely studied, owing to its tremendous potential for full-scale applications, among the existing nondestructive testing methods, for evaluating the stress status of strands. We have employed the theoretical and finite element methods to solve the dispersion curve of single wire and steel strands under various boundary conditions. Thereafter, the singular value decomposition was adopted to work with the simulated and experimental signals for extracting a feature vector that carries valuable stress status information. The effectiveness of the vector was verified by analyzing the relationship between the vector and the stress level. The vector was also used as an input to establish a support vector regression model. The accuracy of the model has been discussed for different sample sizes. The results show that the fundamental mode dispersion curve offset on the high-frequency part and cut-off frequency increases as the boundary constraints enhance. Simulated and experimental results have demonstrated the effectiveness and potential of the proposed support vector regression method for evaluating the stress level in the strands. This method performs well even at low stress levels and the reliability can be enhanced by adding more samples.

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%.

scholarly journals Longitudinal Guided Wave Inspection of Small-Diameter Elbowed Steel Tubes with a Novel Squirrel-Cage Magnetostrictive Sensor

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yao Liu ◽  
Xiucheng Liu ◽  
Chehua Yang ◽  
Wenxin Guo ◽  
Bin Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Guided Waves ◽  
Mode Conversion ◽  
Small Diameter ◽  
Longitudinal Mode ◽  
Guided Wave ◽  
Wall Defect ◽  
Squirrel Cage ◽  
Simulation Results ◽  
Magnetostrictive Sensor

In the study, ultrasonic longitudinal mode guided waves were employed to detect defects in elbowed tubes (without welds) with a diameter of 10 mm. Finite element simulation results highlighted that the emitted L(0,1) mode guided waves experienced strong reflection and mode conversion at the elbow region to generate F(1,1) mode, followed by slow and weak F(2,1) mode. The guided wave reflected from the elbow with a through-wall defect was manifested as two overlapped wave packets, which were good indicators of a defective elbow. To conduct L(0,1) mode guided waves inspection on the small-diameter elbowed tubes, a novel tailored squirrel-cage magnetostrictive sensor was employed in the experiment. The new sensor employed the configuration of segmental iron-cobalt strips and small-size permanent magnet arrays. The entire sensor is composed of two identical C-shaped sensor elements and can be recycled and installed conveniently. Experimental results obtained from healthy and defective tubes were consistent with the conclusions obtained from finite element simulations. An artificial through-wall defect at the elbow and a notch defect at the straight part of the tube could be simultaneously detected by L(0,1) mode guided waves through comparing experimental signals with simulation results.

Guided Wave Focusing Mechanics in Pipe

2003 ◽  
Author(s):  
Takahiro Hayashi ◽  
Koichiro Kawashima ◽  
Zongqi Sun ◽  
Joseph L. Rose
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Guided Waves ◽  
Wave Structure ◽  
Guided Wave ◽  
Pipe Inspection ◽  
Specific Point ◽  
Wave Focusing ◽  
Beam Focusing ◽  
Subsequent Time

Guided waves can be used in pipe inspection over long distances. Presented in this paper is a beam focusing technique to improve the S/N ratio of the reflection from a tiny defect. Focusing is accomplished by using non-axisymmetric waveforms and subsequent time delayed superposition at a specific point in a pipe. A semi-analytical finite element method is used to present wave structure in the pipe. Focusing potential is also studied with various modes and frequencies.

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