STRUCTURAL BOND INSPECTION

• US 20150128709A1
• Filed: 11/14/2013
• Published: 05/14/2015
• Est. Priority Date: 11/14/2013
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Tat, Hong H., Bossi, Richard H., Stewart, Alan F.
• Granted Patent: US 10,048,230 B2
• Time in Patent Office: Days
• US Class Current: 73/588
• CPC Class Codes: G01N 19/04 Measuring adhesive force between materials, e.g. of sealing tape, of coating
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/2694 Wings or other aircraft parts
• CPC Class Codes: G01N 29/045 by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks measuring resonant frequency G01H13/00; measuring strength properties by application of mechanical stress G01N3/00
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00

Abstract

A method for determining the presence of damage in a structure includes applying energy to the structure to induce tension shockwaves in the structure. The method also includes detecting sound waves caused by the tension shockwaves using at least one acoustic emission sensor on the surface of the structure. Additionally, the method includes determining the presence of damage in the structure due to the applied energy based on detected sound waves.

Claims

1. A method for determining a presence of damage in a structure, comprising:

applying energy to the structure to induce tension shockwaves in the structure;

detecting sound waves caused by the tension shockwaves using at least one acoustic emission sensor on a surface of the structure; and

determining the presence of damage in the structure due to the applied energy based on detected sound waves.

2. The method of claim 1, wherein detecting the sound waves comprises detecting frequency characteristics of the sound waves, and determining the presence of damage in the structure is based on detected frequency characteristics of the sound waves.

3. The method of claim 2, wherein the frequency characteristics comprise a change in a characteristic frequency associated with the structure when no damage is present, and wherein the presence of the change in the characteristic frequency indicates damage in the structure.

4. The method of claim 1, further comprising estimating expected sound waves, and wherein determining the presence of damage in the structure comprises comparing the expected sound waves with detected sound waves.

5. The method of claim 4, wherein the expected sound waves are estimated based on characteristics of applied energy to the structure.

6. The method of claim 1, wherein the detected sound waves are analyzed to produce a Fast Fourier Transform pattern.

7. The method of claim 1, wherein the at least one acoustic emission sensor is one of fixedly secured to the structure or movable along the surface of the structure.

8. The method of claim 1, wherein applying energy to the structure induces compression shockwaves, and wherein the compression shockwaves convert into the tension shockwaves upon reflection off a surface of the structure.

9. The method of claim 1, wherein the energy comprises at least one laser beam.

10. The method of claim 1, further comprising assessing a minimal strength of the structure based on the determination of whether damage in the structure is present.

11. The method of claim 1, wherein the structure comprises a bonded structure, and wherein damage in the structure comprises a disbond or delamination.

12. The method of claim 1, wherein the structure comprises first and second layers each made from a composite material or a composite material and a metal, and wherein damage is defined as separation of an adhesive layer between and adjoining the first and second layers.

13. The method of claim 1, wherein:

applying energy to the bonded structure comprises applying a first low energy to the bonded structure to induce first tension shockwaves, applying a second high energy to the bonded structure to induce second tension shockwaves, and applying a third low energy to the bonded structure to induce third tension shockwaves;

detecting sound waves comprises detecting first sound waves caused by the first tension shockwaves, second sound waves caused by the second tension shockwaves, and third sound waves caused by the third tension shockwaves; and

determining the presence of damage in the bonded structure due to the applied energy comprises comparing the first sound waves to the third sound waves.

14. The method of claim 13, wherein a variation between a frequency pattern of the first sound waves and a frequency pattern of the third sound waves indicates the presence of damage in the bonded structure.

15. A system for concurrently determining strength of a bonded structure and presence of disbonds in the bonded structure, comprising:

a wave induction tool that induces a shockwave in the bonded structure;

a sound wave sensing device that detects a sound wave induced by the shockwave, the sound wave sensing device being in direct contact with a surface of the bonded structure; and

a controller that determines the presence of disbonds in the bonded structure based on characteristics of the sound wave detected by the sound wave sensing device, and determining the strength of the bonded structure based on the presence of disbonds in the bonded structure.

16. The system of claim 15, wherein the wave induction tool is movable along a surface of the bonded structure and the sound wave sensing device is non-movably coupled to a surface of the bonded structure.

17. The system of claim 15, wherein the wave induction tool and the sound wave sensing device is movable along a surface of the bonded structure.

18. The system of claim 15, wherein the sound wave sensing device comprises at least two acoustic emission sensors, and wherein the acoustic emission sensors are positioned on a surface of the bonded structure, a first of the acoustic emission sensors being a first distance away from a shockwave induction region in the bonded structure and a second of the acoustic emission sensors being a second distance away from the shockwave induction region, wherein the first distance is different than the second distance.

19. The system of claim 15, wherein the strength of the bonded structure corresponds with a strength of the shockwave necessary to create a disbond in the bonded structure.

21. The apparatus of claim 19, wherein the acoustic emission detection module is configured to determine the presence of a disbond in the bonded structure based on at least one characteristic of the laser beam transmitted onto the bonded structure.

20. An apparatus for concurrently testing strength of a bonded structure and determining a presence of disbonds in the bonded structure, comprising:

a laser bond inspection module configured to command a transmission of a laser beam onto the bonded structure to induce a shockwave in the bonded structure;

at least one acoustic emission sensor in contact with a surface of the bonded structure; and

an acoustic emission detection module configured to determine the presence of a disbond in the bonded structure and verify a strength of the bond based on at least one frequency characteristic of a sound wave in the bonded structure induced by the shockwave, the sound wave being detected by the at least one acoustic emission sensor.