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.

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.

New Magnetostrictive Transducers and Applications for SHM of Pipes and Vessels

2019 ◽  
Author(s):  
Sergey Vinogradov ◽  
Jay L. Fisher
Keyword(s):  
Magnetic Field ◽  
Guided Waves ◽  
Permanent Magnets ◽  
Elevated Temperatures ◽  
Service Industry ◽  
Guided Wave ◽  
Transverse Motion ◽  
Time Varying ◽  
Transducer Design ◽  
Magnetostrictive Transducer

Abstract The use of guided waves for long-range inspection of components is a rapidly growing area of the nondestructive evaluation service industry. Magnetostrictive sensors utilizing ferromagnetic strip material for the transduction effect have proven to be very effective for guided wave testing (GWT) on a variety of components. There is still a demand for enhanced sensor characterization and sensors with specific characteristics. The most challenging area is structural health monitoring (SHM) of components operating at elevated temperatures of at least 200°C. A new configuration of a sensor for generating and receiving transverse-motion guided waves swaps the biasing and time-varying magnetic field directions. This alternative design is a reversed Wiedemann effect magnetostrictive transducer. These transducers exhibit a number of unique features compared with the more conventional Wiedemann sensor, including: (1) the use of smaller rare earth permanent magnets to achieve large, uniform, and self-sustained bias fields; (2) the use of more efficient electric coil arrangements to induce a stronger time-varying magnetic field for a given coil impedance; (3) the ability to generate both transverse and longitudinal waves; (4) they can be used on pipes ranging from a few millimeters to several meters in diameter. In this paper, the new transducer design will be described and its performance will be analyzed in application to SHM of pressurized pipe operating at 200°C and automated omnidirectional scan of large storage tank walls.

scholarly journals Signal Strength Enhancement of Magnetostrictive Patch Transducers for Guided Wave Inspection by Magnetic Circuit Optimization

2019 ◽  
Vol 9 (7) ◽  
pp. 1477 ◽  
Author(s):  
Jianjun Wu ◽  
Zhifeng Tang ◽  
Keji Yang ◽  
Fuzai Lv
Keyword(s):  
Magnetic Field ◽  
Magnetic Circuit ◽  
Energy Conversion Efficiency ◽  
Wave Generation ◽  
Guided Wave ◽  
Shear Mode ◽  
Circuit Optimization ◽  
Affecting Factors ◽  
Long Distance ◽  
Dynamic Magnetic Field

Magnetostrictive patch transducers (MPT) with planar coils are ideal candidates for shear mode generation and detection in pipe and plate inspection with the advantages of flexibility, lightness and good directivity. However, the low energy conversion efficiency limits the application of the MPT in long distance inspection. In this article, a method for the enhancement of the MPT was proposed by dynamic magnetic field optimization using a soft magnetic patch (SMP). The SMP can reduce the magnetic resistance of the magnetic circuit, which increases the dynamic magnetic field intensity in the magnetostrictive patch during wave generation and restricts the induced dynamic magnetic field within the area around the coils for sensing during wave detection. Numerical simulations carried out at different frequencies verified the improvement of the dynamic magnetic fields by the SMP and influence of different affecting factors. The experimental validations of the signal enhancement in wave generation and detection were performed in an aluminum plate. The amplitude magnification could reach 12.7 dB when the MPTs were covered by the SMPs. Based on the numerical and experimental results, the SMP with a large relative permeability and thickness and close fitting between the SMP and coils were recommended when other application conditions were met.

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.

Transmittal properties of a superconductor-ferromagnetic metamaterial subjected to magnetic fields generated by the permanent magnets

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542049
Author(s):  
H. Liu ◽  
X. T. Li ◽  
P. B. Zhou ◽  
H. Zhang ◽  
C. Yang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Permanent Magnets ◽  
Transformation Optics ◽  
Optimal Structure ◽  
Magnetic Shielding ◽  
Static Magnetic Fields ◽  
Coaxial Cylinders ◽  
Geometrical Distribution ◽  
The Magnetic Field

Superconductor-ferromagnetic (FN) metamaterial with effective magnetic shielding and transmittal properties that allow the cloaking and transferring of static magnetic fields has been introduced. Most metamaterials consist of different arrangements of superconducting and ferromagnetic materials whose performance and feasibility mainly depend on the involved materials, their geometrical distribution and the permeability of each. In this paper, combining the method of transformation optics with the design of metamaterials, we experimentally demonstrated a superconductor-FM metamaterial system, composed of two coaxial cylinders of different lengths, to investigate the influence of the length and the properties of superconducting material on the magnetic transferring properties of the magnetic field produced by the permanent magnets. By comparing the transmittal magnetic field of different cases, the optimal structure has been ultimately achieved in terms of calculating the transmitted magnetic field ratios. The insights attained by the present study are aimed to provide useful implications for the design of wireless energy transmission and increasing the efficiency of magnetic transmittal devices.

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 Impact of Static Magnetic Field on the Antioxidant Defence System of Mice Fibroblasts

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Marek Glinka ◽  
Stanisław Gawron ◽  
Aleksander Sieroń ◽  
Katarzyna Pawłowska-Góral ◽  
Grzegorz Cieślar ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Magnetic Field ◽  
Magnetic Fields ◽  
Static Magnetic Field ◽  
Permanent Magnets ◽  
Energy State ◽  
Redox Homeostasis ◽  
Static Magnetic Fields ◽  
Antioxidant Defence System ◽  
The Impact

Results of research assessing the biological impact of static magnetic fields are controversial. So far, they have not provided a clear answer to their influence on cell functioning. Since the use of permanent magnets both in everyday life and in industry becomes more and more widespread, the investigations are continued in order to explain these controversies and to evaluate positive applications. The goal of current work was to assess the impact of static magnetic field of different intensities on redox homeostasis in cultures of fibroblasts. The use of permanent magnets allowed avoiding the thermal effects which are present in electromagnets. During the research we used 6 chambers, designed exclusively by us, with different values of field flux density (varying from 0.1 to 0.7 T). We have noted the decrease in the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx). The static magnetic fields did not modify the energy state of fibroblasts— adenosine triphosphate (ATP) concentration was stable, as well as the generation of malondialdehyde (MDA)—which is a marker of oxidative stress. Results of research suggest that static magnetic fields generated by permanent magnets do not cause oxidative stress in investigated fibroblasts and that they may show slight antioxidizing activity.

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