scholarly journals Excitation efficiency analysis and mode selection on ultrasonic guided wave mixing

2019 ◽  
Author(s):  
Qian Wang ◽  
Wujun Zhu ◽  
Yanxun Xiang ◽  
Mingxi Deng ◽  
Fu-Zhen Xuan
Keyword(s):  
Mode Selection ◽  
Efficiency Analysis ◽  
Guided Wave ◽  
Wave Mixing ◽  
Excitation Efficiency ◽  
Ultrasonic Guided Wave

scholarly journals Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning

2013 ◽  
Vol 113 (14) ◽  
pp. 144904 ◽  
Author(s):  
Pasi Karppinen ◽  
Ari Salmi ◽  
Petro Moilanen ◽  
Timo Karppinen ◽  
Zuomin Zhao ◽  
...  
Keyword(s):  
Laser Diode ◽  
Mode Selection ◽  
Wave Mode ◽  
Guided Wave ◽  
Diode Array ◽  
Laser Diode Array ◽  
Ultrasonic Guided Wave

EMAT Generation of Horizontally Polarized Guided Shear Waves for Ultrasonic Pipe Inspection

1998 ◽  
Author(s):  
Julie Gauthier ◽  
Vasile Mustafa ◽  
Ahmad Chabbaz ◽  
D. Robert Hay
Keyword(s):  
Mode Selection ◽  
Single Mode ◽  
Guided Wave ◽  
Sh Wave ◽  
Sh Waves ◽  
Acoustic Transducers ◽  
Ultrasonic Guided Wave ◽  
Cylindrical Steel ◽  
Pulse Echo ◽  
Multi Mode

In this work, an ultrasonic guided wave inspection technique was evaluated to detect and locate defects in pipes using SH (Horizontally polarized Shear) plate waves. Electromagnetic Acoustic Transducers (EMATs) were designed and constructed for bi-mode SH waves applications. These probes were used to generate a single mode at a time. Advantages of SH waves, guided by the wall surfaces for circumferential propagation and full volume inspection, are demonstrated in the pulse-echo setup. Mode selection criteria were investigated to tune the SH waves to the geometry of the inspection specimen Examples of mode selection based on the interaction characteristics of SH wave modes with a defect are described. An application of multi-mode inspection for geometrical parameter evaluation (length, depth and orientation) of individual cracks was also demonstrated. The experimental work was performed on cylindrical steel pipe samples having several types of defects ranging from through wall cracks to shallow cracks (10% of wall thickness) both in the circumferential and longitudinal directions. Results from laboratory investigation of the influence of defect depth and orientation on reflectivity of various modes of SH waves are reported. Multi-mode SH-wave inspection is shown to be capable of detecting shallow discontinuities (microcracks) and of locating defects accurately. Inspection results on a pipe section are represented as 3-D images with B-Scan projections and their interpretation is discussed.

scholarly journals An Ultrasonic Guided Wave Mode Selection and Excitation Method in Rail Defect Detection

2019 ◽  
Vol 9 (6) ◽  
pp. 1170 ◽  
Author(s):  
Hongmei Shi ◽  
Lu Zhuang ◽  
Xining Xu ◽  
Zujun Yu ◽  
Liqiang Zhu
Keyword(s):  
Mode Shape ◽  
Strain Energy ◽  
Mode Selection ◽  
Wave Mode ◽  
Guided Wave ◽  
Rail Head ◽  
Ultrasonic Guided Wave ◽  
Phase Velocity Dispersion ◽  
Excitation Method ◽  
Shape Data

Different guided wave mode has different sensitivity to the defects of rail head, rail web and rail base in the detection of rail defects using ultrasonic guided wave. A novel guided wave mode selection and excitation method is proposed, which is effective for detection and positioning of the three parts of rail defects. Firstly, the mode shape data in a CHN60 rail is obtained at the frequency of 35 kHz based on SAFE method. The guided wave modes are selected, combining the strain energy distribution diagrams with the phase velocity dispersion curves of modes, which are sensitive to the defects of the rail head, rail web and rail base. Then, the optimal excitation direction and excitation node of the modes are calculated with the mode shape matrix. Phase control and time delay technology are employed to achieve the expected modes enhancement and interferential modes suppression. Finally, ANSYS is used to excite the specific modes and detect defects in different rail parts to validate the proposed methods. The results show that the expected modes are well acquired. The selected specific modes are sensitive to the defects of different positions and the positioning error is small enough for the maintenance staff to accept.

Goodness dispersion curves for ultrasonic guided wave based SHM: a sample problem in corrosion monitoring

2010 ◽  
Vol 114 (1151) ◽  
pp. 49-56 ◽  
Author(s):  
H. Gao ◽  
J. L. Rose
Keyword(s):  
Dispersion Curve ◽  
Group Velocity ◽  
Velocity Dispersion ◽  
Group Velocity Dispersion ◽  
Mode Selection ◽  
Dispersion Curves ◽  
Guided Wave ◽  
Corrosion Monitoring ◽  
General Corrosion ◽  
Ultrasonic Guided Wave

Abstract Ultrasonic guided wave techniques have great potential for structural health monitoring applications. Appropriate mode and frequency selection is the basis for achieving optimised damage monitoring performance. In this paper, several important guided wave mode attributes are introduced in addition to the commonly used phase velocity and group velocity dispersion curves while using the general corrosion problem as an example. We first derive a simple and generic wave excitability function based on the theory of normal mode expansion and the reciprocity theorem. A sensitivity dispersion curve is formulated based on the group velocity dispersion curve. Both excitability and sensitivity dispersion curves are verified with finite element simulations. Finally, a goodness dispersion curve concept is introduced to evaluate the tradeoffs between multiple mode selection objectives based on the wave velocity, excitability and sensitivity.

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 Rail Diagnostics Based on Ultrasonic Guided Waves: An Overview

2021 ◽  
Vol 11 (3) ◽  
pp. 1071
Author(s):  
Davide Bombarda ◽  
Giorgio Matteo Vitetta ◽  
Giovanni Ferrante
Keyword(s):  
Guided Waves ◽  
Structural Integrity ◽  
Diagnostic Procedures ◽  
Guided Wave ◽  
Rolling Stock ◽  
Technical Literature ◽  
Track Maintenance ◽  
Rail Network ◽  
Ultrasonic Guided Wave ◽  
Maintenance And Inspection

Rail tracks undergo massive stresses that can affect their structural integrity and produce rail breakage. The last phenomenon represents a serious concern for railway management authorities, since it may cause derailments and, consequently, losses of rolling stock material and lives. Therefore, the activities of track maintenance and inspection are of paramount importance. In recent years, the use of various technologies for monitoring rails and the detection of their defects has been investigated; however, despite the important progresses in this field, substantial research efforts are still required to achieve higher scanning speeds and improve the reliability of diagnostic procedures. It is expected that, in the near future, an important role in track maintenance and inspection will be played by the ultrasonic guided wave technology. In this manuscript, its use in rail track monitoring is investigated in detail; moreover, both of the main strategies investigated in the technical literature are taken into consideration. The first strategy consists of the installation of the monitoring instrumentation on board a moving test vehicle that scans the track below while running. The second strategy, instead, is based on distributing the instrumentation throughout the entire rail network, so that continuous monitoring in quasi-real-time can be obtained. In our analysis of the proposed solutions, the prototypes and the employed methods are described.

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