Hand-held sound source for sonic infrared imaging of defects in materials

• US 20040245469A1
• Filed: 05/05/2004
• Published: 12/09/2004
• Est. Priority Date: 09/16/1999
• Status: Active Grant

• Current Assignee: Wayne State University
• Original Assignee: Wayne State University
• Inventors: Han, Xiaoyan, Thomas, Robert L., Favro, Lawrence D.
• Granted Patent: US 7,064,332 B2
• Time in Patent Office: Days
• US Class Current: 250/341.6
• CPC Class Codes: G01N 2291/02483 Other human or animal parts, e.g. bones
• CPC Class Codes: G01N 2291/02827 Elastic parameters, strength or force
• CPC Class Codes: G01N 2291/0289 Internal structure, e.g. defects, grain size, texture
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 2291/2638 Complex surfaces
• CPC Class Codes: G01N 2291/2694 Wings or other aircraft parts
• CPC Class Codes: G01N 25/72 Investigating presence of flaws
• CPC Class Codes: G01N 29/223 Supports, positioning or alignment in fixed situation mounting transducers per se G10K11/004
• 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: G01N 29/28 providing acoustic coupling , e.g. water impedance matching G10K11/02
• CPC Class Codes: G01N 29/346 with amplitude characteristics, e.g. modulated signal
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00
• CPC Class Codes: G01N 29/449 Statistical methods not provided for in G01N29/4409, e.g. averaging, smoothing and interpolation

Abstract

A hand-held sound source for use in an infrared or thermal imaging system that detects sub-surface defects in a structure. The sound source includes a transducer that is positioned against the structure to emit a sound signal into the structure. The sound source further includes an adjustable spring that pushes the transducer against the structure with a predetermined amount of force so that the sound energy is effectively coupled into the structure. The sound source also includes three stabilizing legs that stabilize the transducer on the structure. The length of each leg can be adjustable relative to the length of the other legs so that the sound source can be used against irregular surfaces.

Claims

1. A thermal imaging system for detecting defects in a structure, said system comprising:

a hand-held sound source, said sound source including a housing, a handle assembly coupled to the housing, a sound transducer coupled to the housing and three stabilizing members extending from the housing, said sound source further including a spring mounted within the housing, wherein the spring pushes the transducer out of the housing, and wherein the transducer is positioned against the structure against the bias of the spring so that the three stabilizing members are positioned against the structure and the transducer provides a predetermined force against the structure;

a thermal imaging camera directed towards the structure and generating thermal images of the defects in the structure; and

a control unit electrically coupled to the sound source and the camera, said control unit causing the sound source to emit pulses of a sound signal at a predetermined frequency and for a predetermined duration, and causing the camera to generate sequential images of the structure, wherein the signal from the sound source causes the defects in the structure to heat up and be visible in the images generated by the camera.

2. The system according to claim 1 wherein the sound source further includes a positioning device coupled to the housing, said spring being pushed against the positioning device where the position of the positioning device sets the force applied by the transducer against the structure.

3. The system according to claim 2 wherein the positioning device is threaded into an end of the housing.

4. The system according to claim 1 wherein the handle assembly includes an annular ring portion positioned around an outside surface of the housing and two handles extending from the ring portion on opposite sides of the housing.

5. The system according to claim 4 wherein the stabilizing members are secured to the ring portion.

6. The system according to claim 1 further comprising a coupler positioned between and in contact with the structure and an end of the transducer.

7. The system according to claim 1 wherein the stabilizing members are symmetrically disposed about the housing.

8. The system according to claim 1 wherein the length of each stabilizing member is selectively adjustable relative to the length of the other stabilizing members.

9. The system according to claim 1 wherein the housing is a cylindrical housing.

10. The system according to claim 1 wherein the transducer is an ultrasonic transducer.

11. A hand-held sound source for delivering sound energy to a structure, said sound source comprising:

a body portion defining a chamber therein;

a transducer extending from the body portion;

a plurality of stabilizing members extending from the body portion;

a handle assembly mounted to the body portion;

a positioning device secured to the body portion and being selectively movable relative thereto; and

a spring positioned within the body portion against the positioning device, wherein the transducer is positioned against the structure against the bias of the spring so that the plurality of stabilizing members are positioned against the structure and the transducer provides a predetermined force against the structure.

12. The source according to claim 11 wherein the plurality of stabilizing members is three symmetrically disposed stabilizing members.

13. The source according to claim 11 wherein the positioning device is threaded into an end of the body portion.

14. The source according to claim 11 wherein the handle assembly includes an annular ring portion positioned around an outside surface of the body portion and two handles extending from the ring portion on opposite sides of the body portion.

15. The source according to claim 14 wherein the stabilizing members are secured to the ring portion.

16. The source according to claim 11 wherein the length of each stabilizing member is selectively adjustable relative to the length of the other stabilizing members.

17. The source according to claim 11 wherein the transducer is an ultrasonic transducer.

18. A method of detecting defects in a structure, said method comprising:

providing a sound source including a body portion, a handle assembly coupled to the body portion, a sound transducer coupled to the body portion and three stabilizing members extending from the housing, said sound source further including a spring mounted within the body portion, wherein the spring pushes the transducer out of the body portion, and wherein the transducer is positioned against the structure against the bias of the spring so that the three stabilizing members are positioned against the structure and the transducer provides a predetermined force against the structure;

emitting at least one pulse of a sound signal from the sound source into the structure to heat the defects; and

generating a sequence of thermal images of the structure prior to, during and after the emission of the sound signal.

19. The method according to claim 18 wherein providing a sound source includes threading the positioning device into an end of the body portion.

20. The method according to claim 18 wherein providing a sound source includes providing the handle assembly with an annular ring portion positioned around an outside surface of the body portion and two handles extending from the ring portion on opposite sides of the body portion.

21. The method according to claim 20 wherein providing a sound source includes securing the stabilizing members to the ring portion.

22. The method according to claim 18 wherein providing a sound source includes selectively adjusting the length of each stabilizing member relative to the length of the other stabilizing members.

23. The method according to claim 18 wherein providing a sound source includes providing an ultrasonic transducer.