Omni-directional shear-horizontal wave electromagnetic acoustic transducer

Patent metadata

Field	Value
Publication number	US-9664650-B2
Application number	US-201514676198-A
Country	US
Kind code	B2
Filing date	Apr 1, 2015
Priority date	Jul 2, 2014
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

A transducer is provided. The transducer includes: a permanent magnet unit formed in a form of a circular ring having upper and lower surfaces each having a predetermined diametrical direction width while having a circular through-portion in a central portion of the permanent magnet unit, the permanent magnet unit generating a vertical magnetic flux due to opposite magnetic poles that are formed in the upper and lower surfaces; and a coil wound in a diametrical direction across an area between an inner surface formed by the circular through-portion of the permanent magnet and an outer surface formed by an outer circumference of the permanent magnet and also wound in a circumferential direction of the permanent magnet, wherein the coil comprises a conductive material so that a current is applied to the coil, and when an alternating current is applied to the coil, a direction of the alternating current flowing along the coil and a direction of a magnetic field passing through the coil are orthogonal to each other.

First claim

What is claimed is:

1. A transducer comprising:
a permanent magnet unit formed in a form of a circular ring having upper and lower surfaces each having a predetermined diametrical direction width while having a circular through-portion in a central portion of the permanent magnet unit, the permanent magnet unit generating a vertical magnetic flux due to opposite magnetic poles that are formed in the upper and lower surfaces; and
a coil wound in a diametrical direction across an area between an inner surface formed by the circular through-portion of the permanent magnet and an outer surface formed by an outer circumference of the permanent magnet and also wound in a circumferential direction of the permanent magnet,
wherein the coil comprises a conductive material so that a current is applied to the coil, and when an alternating current is applied to the coil, a direction of the alternating current flowing along the coil and a direction of a magnetic field passing through the coil are orthogonal to each other,
wherein the permanent magnet unit comprises:
a first permanent magnet unit formed in a form of a circular ring having upper and lower surfaces each having a predetermined diametrical direction width while having a first circular through-portion in a central portion of the first permanent magnet unit, the first permanent magnet unit generating a vertical magnetic flux due to opposite magnetic poles that are formed in the upper and lower surfaces; and
a second permanent magnet unit disposed inside the first circular through-portion and formed in a form of a circular ring having upper and lower surfaces each having a predetermined diametrical direction width and a predetermined area while having a second circular through-portion in a central portion of the second permanent magnet unit, the second permanent magnet unit having an outer diameter corresponding to an inner diameter of the first circular through-portion and generating a vertical magnetic flux due to opposite magnetic poles that are formed in the upper and lower surfaces,
wherein the coil is wound in the diametrical direction across an area between an inner surface formed by the second circular through-portion and an outer surface formed by an outer circumference of the first permanent magnet unit, and a surface of the first permanent magnet unit and a surface of the second permanent unit, which have different magnetic poles, are positioned on the same oriented surface so as to have magnetic flux in opposite directions.

2. The transducer of claim 1 , wherein the predetermined diametrical direction width of the permanent magnet is half a wavelength corresponding to a shear-horizontal wave having a frequency to be generated.

3. The transducer of claim 1 , wherein a diametrical direction width of the first permanent magnet unit is equal to a diametrical direction width of the second permanent magnet unit.

4. The transducer of claim 1 , wherein a diametrical direction width of the first permanent magnet unit, a diametrical direction width of the second permanent magnet unit, and a diameter of the second circular through-portion are equal to each other.

5. The transducer of claim 1 , wherein the coil comprises:
a first winding portion crossing a circular ring; and
a second winding portion crossing the circular ring in the diametrical direction as the first winding portion in the state in which the second winding portion extends from the first winding portion in a circumferential direction in an outer circumference portion of the circular ring and thus is spaced apart by a predetermined distance from the first winding portion.

6. The transducer of claim 1 , wherein the coil is wound at regular intervals while having the same angle in the circumferential direction of the permanent magnet.

7. The transducer of claim 1 , further comprising a fixing unit attached to the permanent magnet,
wherein the fixing unit comprises an adhesive to fix the position of the coil.

Assignees

• Univ Seoul Nat R & Db Found
• Seoul Nat Univ R & Db Found

Inventors

• Seung Hong Min
• Kim Yoon Young

Classifications

• G01N29/2412 Primary

  using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; (investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18) · CPC title

• G01N2291/0427

  Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever · CPC title

• G01N2291/0422

  Shear waves, transverse waves, horizontally polarised waves · CPC title