A study on torsional guided wave EMAT array and its application in embedment depth inspection of guardrail post

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1065-1072
Author(s):  
Yinghong Zhang ◽  
Bin Wang ◽  
Xiao Wei ◽  
Zhenghua Qian
Keyword(s):  
Guided Waves ◽  
Permanent Magnets ◽  
Ultrasonic Transducer ◽  
Experimental System ◽  
Guided Wave ◽  
Embedment Depth ◽  
Torsional Mode ◽  
Working Principle ◽  
Different Depths ◽  
Set Up

It is always a challenge to quickly and effectively inspect the embedment depth of highway guardrail posts. This paper focuses on an electromagnetic ultrasonic transducer (EMAT) array that can excites torsional mode (T-mode) guided waves and applies it to check the embedment depth of guardrail posts. First of all, we presented a torsional guided wave EMAT array that can be used to quickly inspect the embedment depth of guardrail posts. The working principle of the EMAT array was described in detail. Secondly, a torsional guided wave EMAT array composed of 12 racetrack coils and 24 permanent magnets was simulated to verify the excitation and propagation process of torsional guided wave in a post. Then, a method for detecting the embedment depth of a post using the travel time of a torsional guided wave in the post was put forward. Finally, an experimental system was set up to carry out embedment depth detection experiments on posts with different depths buried in soil and concrete. Experiments have verified the feasibility of using the torsional guided wave EMAT array to inspect the embedment depth of the guardrail post.

scholarly journals Numerical Investigation of Excitation of Various Lamb Waves Modes in Thin Plastic Films

2022 ◽  
Vol 12 (2) ◽  
pp. 849
Author(s):  
Rymantas Jonas Kazys ◽  
Justina Sestoke ◽  
Egidijus Zukauskas
Keyword(s):  
Numerical Investigation ◽  
Lamb Wave ◽  
Guided Waves ◽  
Phased Array ◽  
Ultrasonic Transducer ◽  
Guided Wave ◽  
Ultrasonic Guided Waves ◽  
Plastic Films ◽  
Thin Plastic ◽  
Wave Modes

Ultrasonic-guided waves are widely used for the non-destructive testing and material characterization of plates and thin films. In the case of thin plastic polyvinyl chloride (PVC), films up to 3.2 MHz with only two Lamb wave modes, antisymmetrical A0 and symmetrical S0, may propagate. At frequencies lower that 240 kHz, the velocity of the A0 mode becomes slower than the ultrasonic velocity in air which makes excitation and reception of such mode complicated. For excitation of both modes, we propose instead a single air-coupled ultrasonic transducer to use linear air-coupled arrays, which can be electronically readjusted to optimally excite and receive the A0 and S0 guided wave modes. The objective of this article was the numerical investigation of feasibility to excite different types of ultrasonic-guided waves, such as S0 and A0 modes in thin plastic films with the same electronically readjusted linear phased array. Three-dimensional and two-dimensional simulations of A0 and S0 Lamb wave modes using a single ultrasonic transducer and a linear phased array were performed. The obtained results clearly demonstrate feasibility to excite efficiently different guided wave modes in thin plastic films with readjusted phased array.

scholarly journals Attenuation of a Slow Subsonic A0 Mode Ultrasonic Guided Wave in Thin Plastic Films

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1648 ◽  
Author(s):  
Rymantas Kažys ◽  
Reimondas Šliteris ◽  
Liudas Mažeika ◽  
Olgirdas Tumšys ◽  
Egidijus Žukauskas
Keyword(s):  
Guided Waves ◽  
High Efficiency ◽  
Lamb Waves ◽  
Ultrasonic Transducer ◽  
Plane Waves ◽  
Ultrasound Velocity ◽  
Guided Wave ◽  
Low Frequencies ◽  
Plastic Films ◽  
Thin Plastic

The ultrasonic testing technique using Lamb waves is widely used for the non-destructive testing and evaluation of various structures. For air-coupled excitation and the reception of A0 mode Lamb waves, leaky guided waves are usually exploited. However, at low frequencies (<100 kHz), the velocity of this mode in plastic and composite materials can become slower than the ultrasound velocity in air, and its propagation in films is accompanied only by an evanescent wave in air. To date, the information about the attenuation of the slow A0 mode is very contradictory. Therefore, the objective of this investigation was the measurement of the attenuation of the slow A0 mode in thin plastic films. The measurement of the attenuation of normal displacements of the film caused by a propagating slow A0 mode is discussed. The normal displacements of the film at different distances from the source were measured by a laser interferometer. In order to reduce diffraction errors, the measurement method based on the excitation of cylindrical but not plane waves was proposed. The slow A0 mode was excited in the polyvinylchloride film by a dry contact type ultrasonic transducer made of high-efficiency PMN-32%PT strip-like piezoelectric crystal. It was found that that the attenuation of the slow A0 mode in PVC film at the frequency of 44 kHz is 2 dB/cm. The obtained results can be useful for the development of quality control methods for plastic films.

scholarly journals Performance analysis of a four-stroke compressed air engine

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 113-126
Author(s):  
Fancong Zeng ◽  
Jinli Xu
Keyword(s):  
Mathematical Model ◽  
Experimental System ◽  
Compressed Air ◽  
Work Efficiency ◽  
Supply Pressure ◽  
Numerical Studies ◽  
Optimizing Design ◽  
Working Principle ◽  
Working Performance ◽  
Set Up

The purpose of this paper is to investigate working performance for a four-stroke compressed air engine via numerical studies. A mathematical model is developed to study the influence of several operative parameters on working performance. The mathematical model consists of thermodynamic model, each stroke model and dynamic model. In addition, a working principle and an experimental system of the compressed air engine are set up. The aims are: to introduce the novel four-stroke engine and to quantify the influence of rotational speed, supply pressure and supply temperature on working characteristics. The simulation and analysis show several meaningful results. The compressed air engine has higher cylinder pressure and work efficiency in lower speed stage, and the increase of the supply pressure can effectively improve indicated work and work efficiency. However, supply temperature has little effect on the performance of the compressed air engine. Therefore, the study of this work will provide a certain guidance function for further study on optimizing design of the compressed air engine.

Defect Detection in Seven-Wire Steel Strands Using Single Magnetostrictive Transducer with Two-Layer Coil

2010 ◽  
Vol 34-35 ◽  
pp. 456-461 ◽  
Author(s):  
Zeng Hua Liu ◽  
Ji Chen Zhao ◽  
Bin Wu ◽  
Cun Fu He
Keyword(s):  
Guided Waves ◽  
Permanent Magnets ◽  
Signal To Noise Ratio ◽  
Wave Mode ◽  
Guided Wave ◽  
High Signal ◽  
Helical Surface ◽  
Artificial Defect ◽  
Wire Steel ◽  
Magnetostrictive Transducer

In order to achieve active health monitoring of seven-wire steel strands, single magnetostrictive transducer with two-layer coil is developed and applied for the excitation and reception of ultrasonic longitudinal guided waves simultaneously. The transducer can be conveniently fixed at any single one position on the helical surface of these structures. The inner and outer layers of its coil are used for excitation and reception respectively with the help of same axisymmetric permanent magnets. Experimental results show that chosen ultrasonic longitudinal guided wave mode, L(0,1) at 140kHz, can be excited and received with high signal-to-noise ratio in steel strands by using the developed magnetostrictive transducer. Furthermore, to identify the performance of the transducer, the detection of an artificial defect is also conducted.

A flexural mode guided wave transducer for pipes based on magnetostrictive effect

2020 ◽  
Vol 64 (1-4) ◽  
pp. 335-342
Author(s):  
Yun Sun ◽  
Jiang Xu ◽  
Chaoyue Hu ◽  
Guang Chen ◽  
Yunfei Li
Keyword(s):  
Magnetic Field ◽  
Guided Waves ◽  
Permanent Magnets ◽  
Wave Structure ◽  
Guided Wave ◽  
Circumferential Direction ◽  
Bias Magnetic Field ◽  
Flexural Mode ◽  
Axial Crack ◽  
Wave Transducer

The flexural mode guided waves of pipes which are sensitive the axial crack and suitable for wave focused gain more attention recently. In this paper, a non-contact flexural mode guided wave transducer based on magnetostrictive effect is provided for pipes. Based on the magnetostrictive transduction principle and the wave structure of the flexural mode guided wave, the sensing method for generating and receiving the flexural mode guided waves based on magnetostrictive effect is obtained. According to the theoretical analysis, a non-contact magnetostrictive transducer for F (3, m) mode guided waves is given. Six permanent magnets which are evenly distributed in the circumferential direction of the pipe and arranged in opposite polarities are employed to provide the bias magnetic field in the circumferential direction. A solenoid coil is employed to induce the axial alternating magnetic field. The bias magnetic field distribution of the flexural mode guided wave in the pipeline is analyzed by the finite element simulation. The mode of the transduction guided wave in the pipe is verified by experiments based on the dispersion curves.

scholarly journals Ultrasonic Guided Waves in Piezoelectric Layered Composite with Different Interfacial Properties

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Xiao Chen
Keyword(s):  
Guided Waves ◽  
Interfacial Properties ◽  
Layered Composite ◽  
Guided Wave ◽  
Propagation Model ◽  
Ultrasonic Guided Waves ◽  
Piezoelectric Composite ◽  
Order Mode ◽  
Ultrasonic Guided Wave ◽  
Different Depths

Combining the propagation model of guided waves in a multilayered piezoelectric composite with the interfacial model of rigid, slip, and weak interfaces, the generalized dispersion characteristic equations of guided waves propagating in a piezoelectric layered composite with different interfacial properties are derived. The effects of the slip, weak, and delamination interfaces in different depths on the dispersion properties of the lowest-order mode ultrasonic guided wave are analyzed. The theory would be used to characterize the interfacial properties of piezoelectric layered composite nondestructively.

scholarly journals Online Structural Health Monitoring of Rotating Machinery via Ultrasonic Guided Waves

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Ming Li ◽  
Guang Meng ◽  
Hongguang Li ◽  
Jianxi Qiu ◽  
Fucai Li
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Guided Waves ◽  
Experimental System ◽  
Guided Wave ◽  
Ultrasonic Guided Waves ◽  
Numerical Verification ◽  
Structural Health ◽  
Cylindrical Shaft ◽  
Rotating Shafts

This paper focuses on the establishment of the online structural health monitoring strategy for rotating shafts using ultrasonic guided waves. The dispersion of cylindrical shaft is investigated and a conclusion that the longitudinal ultrasonic wave propagating along the cylindrical shaft can hardly be interfered by the rotation is obtained. The experimental system and the numerical simulation model have been constructed, based on the fact that the experimental research and the numerical verification have been conducted intensively. The strategy can be concluded no matter the cracked rotor is at rest or rotating. Comparing with the same rotor without crack, the amplitudes of the guided wave packages descend along the transmission path and the symmetric path where crack exists; however, the amplitude of the wave packages will ascend along the other transmission paths.

scholarly journals Experimental Study of the Guided Wave Directivity Patterns of Thin Removable Magnetostrictive Patches

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7189
Author(s):  
Akram Zitoun ◽  
Steven Dixon ◽  
Graham Edwards ◽  
David Hutchins
Keyword(s):  
Magnetic Field ◽  
Experimental Study ◽  
Guided Waves ◽  
Permanent Magnets ◽  
Guided Wave ◽  
Metallic Plate ◽  
Static Magnetic Fields ◽  
Directivity Patterns ◽  
Spiral Coils ◽  
Dynamic Magnetic Field

The characteristics of removable magnetostrictive thin patches are investigated for the generation of guided waves in plates. The directivity patterns of SH, S0 and A0 modes have been measured in a thin metallic plate for different combinations of static and dynamic magnetic field directions. This used different coil geometries such as racetrack and spiral coils to generate the dynamic magnetic field, as well as separate biasing static magnetic fields from permanent magnets. This arrangement generated signals via both Lorentz and magnetostrictive forces, and the resultant emitted guided waves were studied for different dynamic and static magnetic field directions and magnitudes. It is demonstrated that different guided wave modes can be produced by controlling these parameters.

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.

Simulations and Experiments for the Detection of Flow-Assisted Corrosion in Pipes

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
K. Sathish Kumar ◽  
Krishnan Balasubramaniam
Keyword(s):  
Power Plants ◽  
Permanent Magnets ◽  
Guided Wave ◽  
Transmission Method ◽  
Torsional Mode ◽  
Accelerated Corrosion ◽  
Water Steam ◽  
Ultrasonic Guided Wave ◽  
Radial Depth ◽  
Piping Systems

Flow-accelerated corrosion (FAC) is a phenomenon which causes wall thinning of pipes, fittings, vessels, and other components in the metal based piping systems that carry water or water-steam mixture in power plants and refineries. Currently used nondestructive techniques, such as radiographic testing (RT), ultrasonic testing (UT), and pulsed eddy current (PEC) testing in order to determine the remaining wall thickness, are time consuming and not economical. Hence, in this work, the use of the fundamental torsional mode ultrasonic guided wave to detect FAC was investigated using the finite element method (FEM) simulations and that were validated with experiments. The torsional wave was generated by the magnetostriction principle using surface mounted strips made of magnetostrictive Hyperco (FeCo) material that provided the source for the surface tractions required to generate the ultrasonic guided wave. The transient electric field was provided through a solenoid coil wound over the strips and permanent magnets were employed to provide the bias magnetic field. From this work, it was observed that the pulse-echo method is not suitable for the FAC detection because of the insignificant reflections from FAC defect region that could not be effectively detected. The through-transmission method was found to be more suitable for the FAC detection because the amplitude of transmitted signal decreased with increase in radial depth of FAC in both the simulation and experiment.

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