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

David Hutchins,Akram Zitoun,Steven Dixon,Graham Edwards

doi:10.3390/s20247189

David Hutchins, Akram Zitoun + Show 2 more

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https://doi.org/10.3390/s20247189

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Abstract

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.

Highlights

Non-Destructive Testing (NDT) techniques are widely used for the inspection of different structures in numerous industrial applications
To deal with the efficiency of Electro-Magnetic Acoustic Transducers (EMATs), and to overcome some of the limitations of air-coupled systems, this paper investigates the use of removable magnetostrictive patches that are attached to the surface of the specimen
While magnetostrictive patch transducers (MPTs) have been reported in the literature [17,20], this paper extends the knowledge in this area by systematically studying the variables that affect their operation, and studies the properties of the resulting Guided Waves (GWs) generation

Summary

Introduction

Non-Destructive Testing (NDT) techniques are widely used for the inspection of different structures in numerous industrial applications. Guided Waves (GWs) are among these techniques and they are widely used in different applications such as the inspection of pipes [1,2], rails [3,4] and plates [5,6]. GWs in plates and pipes are complex as they are generally dispersive, some modes, such as the SH0 mode in a plate and the T(0,1) mode in a pipe, can be non-dispersive. Their characteristics are affected by the material properties and the geometry of the structure within which the elastic wave is propagating. The work in this paper concentrates on these two modes, A0 modes can be useful because of their smaller wavelength

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