Waveguide for a bulk-type medium, vibrator using same to transmit shear waves to a bulk-type medium, and method using the vibrator to transmit shear waves to a bulk-type medium

• US 9,527,111 B2
• Filed: 10/05/2012
• Issued: 12/27/2016
• Est. Priority Date: 10/07/2011
• Status: Active Grant

• Current Assignee: SNU R&DB Foundation (Seoul National University)
• Original Assignee: SNU R&DB Foundation (Seoul National University)
• Inventors: Kwon, Young Eui, Jeon, Hyun Joong, Kim, Hoe Woong, Kim, Yoon Young
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US14/350,012
• Publication Number:
  US 20140246954A1
• Time in Patent Office: 1,544 Days
• Field of Search: 333/141, 333/145, 333/147, 333/148, 333/149, 310/311, 310/323.01, 310/323.19, 310326-328, 310/334, 310/26, 310/12.24, 310/152, 310/154.01, 310/154.02, 735/98, 736/44, 738/665
• US Class Current: 1/1
• CPC Class Codes: B06B 1/0644 using a single piezoelectric element B06B1/0688 takes precedence
• CPC Class Codes: B06B 1/08 operating with magnetostriction magnetostrictive devices per se H10N30/00
• CPC Class Codes: B06B 3/00 Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 29/2412 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 Class Codes: G01N 29/2462 Probes with waveguides, e.g. SAW devices
• CPC Class Codes: G10K 11/355 Arcuate movement

Abstract

The aim of the present invention is to provide a waveguide capable of transmitting shear waves in a desired pattern to a bulk-type medium, a vibrator, and a method of transmitting shear waves by using the vibrator. To this end, the present invention provides a waveguide including a vibrating portion that is vibrated by a vibrating unit, a transmitting portion that transmits shear waves generated by the vibrating unit to a bulk-type medium and is thicker than the vibrating portion, and a connecting portion that contacts both the vibrating portion and the transmitting portion and has a thickness varying from a portion contacting the vibrating portion to a portion contacting the transmitting portion. Also, the present invention provides a vibrator using the waveguide and a method of transmitting shear waves by using the vibrator.

Claims

1. A waveguide comprising:

a vibrating portion which has a plate shape, a width w2 and a thickness t2, and is vibrated by a vibrating unit;

a transmitting portion which transmits shear waves generated by the vibrating unit to a bulk-type medium, and has a plate shape, a width w2 and a thickness t3 that is thicker than the thickness t2 of the vibrating portion;

a connecting portion which contacts both the vibrating portion and the transmitting portion and has a thickness varying from a portion contacting the vibrating portion to a portion contacting the transmitting portion; and

a vibrating unit which generates a shear wave in the vibration portion in a direction parallel to the plane of the vibration portion,

wherein the width w2 is larger than the thickness t2 of the vibrating portion and the thickness t3 of the transmitting portion.

2. The waveguide of claim 1, wherein the transmitting portion is installed to contact the bulk-type medium while being used, and

an inclined surface inclined with respect to a longitudinal direction of the waveguide is formed at an end of the transmitting portion contacting the bulk-type medium.

3. A vibrator for transmitting shear waves to a bulk-type medium, the vibrator comprising:

a vibrating unit which vibrates a waveguide to transmit shear waves along the waveguide; and

the waveguide comprising a vibrating portion which has a plate shape, a width w2 and a thickness t2, and is vibrated by a vibrating unit;

a transmitting portion which transmits shear waves generated by the vibrating unit to a bulk-type medium, and has a plate shape, a width w2 and a thickness t3 that is thicker than the thickness t2 of the vibrating portion;

a connecting portion which contacts both the vibrating portion and the transmitting portion and has a thickness varying from a portion contacting the vibrating portion to a portion contacting the transmitting portion; and

a vibrating unit which generates a shear wave in the vibration portion in a direction parallel to the plane of the vibration portion, wherein the width w2 is larger than the thickness t2 of the vibrating portion and the thickness t3 of the transmitting portion.

4. The vibrator of claim 3, wherein the vibrating portion comprises a portion made of a ferromagnetic material,

the vibrating unit comprises:

an insulator which is disposed on the vibrating portion;

meander coils which comprise a plurality of coil lines extending in a width direction of the vibrating portion on the insulator, and are formed such that current flows in opposite directions along coil lines adjacent to each other; and

a magnet which forms a magnetic field in the width direction of the vibrating portion, and

when one or more meander coils selected from among the meander coils are supplied with current, portions of the vibrating portion corresponding to positions where the meander coils are disposed are locally deformed, such that the shear waves are generated at the vibrating portion.

5. The vibrator of any one of claim 4, further comprising a wedge which is interposed between the waveguide and the bulk-type medium, and has a semi-cylindrical shape having a semicircular cross section and a length corresponding to a width of the waveguide that corresponds to the width direction of the vibrating portion,

wherein a contact surface at a lower end of the waveguide is formed as a curved surface corresponding to a curved surface of the wedge, and the shear waves are transmitted in a desired direction to the bulk-type medium when the contact surface of the waveguide is in contact with a desired position on the curved surface of the wedge.

6. The vibrator of claim 3, wherein the vibrating unit comprises:

a mangetostrictive patch which is attached to a surface of the vibrating portion;

an insulator disposed on the magnetostrictive patch;

meander coils which comprise a plurality of coil lines extending in a width direction of the vibrating portion on the insulator, and are formed such that current flows in opposite directions along coil lines adjacent to each other; and

a magnet which forms a magnetic field in a width direction of the magnetostrictive patch, and

when one or more meander coils selected from among the meander coils are supplied with current, portions of the magnetostrictive patch corresponding to positions where the meander coils are disposed are locally deformed, such that the shear waves are generated at the vibrating portion.

7. The vibrator of any one of claim 6, further comprising a wedge which is interposed between the waveguide and the bulk-type medium, and has a semi-cylindrical shape having a semicircular cross section and a length corresponding to a width of the waveguide that corresponds to the width direction of the vibrating portion,

wherein a contact surface at a lower end of the waveguide is formed as a curved surface corresponding to a curved surface of the wedge, and the shear waves are transmitted in a desired direction to the bulk-type medium when the contact surface of the waveguide is in contact with a desired position on the curved surface of the wedge.

8. The vibrator of claim 3, further comprising a wedge which is interposed between the waveguide and the bulk-type medium, and has a semi-cylindrical shape having a semicircular cross section and a length corresponding to a width direction of the waveguide,

wherein a contact surface at a lower end of the waveguide is formed as a curved surface corresponding to a curved surface of the wedge, and

the shear waves are transmitted in a desired direction to the bulk-type medium when the contact surface of the waveguide is in contact with a desired position on the curved surface of the wedge.

9. The vibrator of claim 8, wherein the wedge further comprises:

a link connecting portion which extends from a lower rectangular surface of the semi-cylindrical shape downward toward the bulk-type medium; and

a connecting link which is connected to both the link connecting portion and the waveguide and maintains the waveguide at a position on the wedge.

10. The vibrator of claim 3, wherein the transmitting portion is installed to contact the bulk-type medium while being used, and

an inclined surface inclined with respect to a longitudinal direction of the waveguide is formed at an end of the transmitting portion contacting the bulk-type medium.

11. The vibrator of claim 3, wherein a sound-absorbing material or a backing material preventing reflection of ultrasonic waves in the waveguide is further disposed in the vibrating portion.

12. A method of transmitting shear waves to a bulk-type medium by using a waveguide comprising a vibrating portion vibrated by a vibrating unit, a transmitting portion transmitting shear waves generated by the vibrating unit to a bulk-type medium and being thicker than the vibrating portion, and a connecting portion contacting both the vibrating portion and the transmitting portion and having a thickness varying from a portion contacting the vibrating portion to a portion contacting the transmitting portion, the method comprising:

deciding a pattern and a frequency of the shear waves to be transmitted to the bulk-type medium;

deciding a thickness of the transmitting portion of the waveguide corresponding to the decided pattern;

deciding a thickness of a plate generating only a first mode of the shear waves at the decided frequency, and setting the decided thickness of the plate as a thickness of the vibrating portion; and

connecting the transmitting portion of the waveguide to the bulk-type medium, and transmitting the shear waves to the vibrating portion by using the vibrating unit.

13. The method of claim 12, further comprising:

deciding a propagation direction of the shear waves to be transmitted to the bulk-type medium; and

installing a semi-cylindrical wedge between the transmitting portion and the bulk-type medium, contacting the transmitting portion of the waveguide with the semi-cylindrical wedge, and then disposing the waveguide in parallel to a direction in which the shear waves are to be transmitted.