Laser ultrasound system and method for inspection of a contoured structure

• US 10,539,538 B2
• Filed: 07/09/2015
• Issued: 01/21/2020
• Est. Priority Date: 07/09/2015
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Safai, Morteza, Georgeson, Gary E.
• Primary Examiner(s): Patel, Nimeshkumar D
• Assistant Examiner(s): Fayyaz, Nashmiya S
• Application Number:
  US14/795,467
• Publication Number:
  US 20170010242A1
• Time in Patent Office: 1,657 Days
• Field of Search: 73643, 73655, 3643
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046

Abstract

A method including ultrasonically scanning a structure with a laser ultrasound testing system where the structure is provided with an array of nanoscopic structures, the nanoscopic structures having a predetermined directional orientation, the nanoscopic structures disposed on a scanned surface of the structure, and determining if the structure meets a predetermined threshold. Aspects of this invention apply certain high emissivity coatings to structures for the purpose of significant improvement laser ultrasound inspection of those structures. The nanotechnology-based material in the coatings rapidly draws heat away, for maximum laser energy absorption while preventing surface heat damage to the composite surface from the laser beam.

Claims

1. A method comprising:

ultrasonically scanning a structure with a laser ultrasound testing system by moving a pulsed laser beam across a surface of the structure and detecting ultrasonic waves reflected by the structure, where the structure is provided with an array of nanoscopic structures, the nanoscopic structures having a predetermined directional orientation relative to the structure, where the nanoscopic structures are deposited directly on a scanned surface of the structure by a nanoscopic structure generation module so as to be integrally formed on and depend from, so as to be stationarily fixed to and form a unitary member with, the scanned surface of the structure so that a free end of a respective nanoscopic structure extends from the scanned surface of the structure in the predetermined directional orientation; and

determining, based on ultrasonic scanning of the structure with the laser ultrasound testing system, if the structure meets a predetermined threshold.

2. The method of claim 1, further comprising directing incident energy from the laser ultrasound testing system into the structure using the array of nanoscopic structures.

3. The method of claim 1, wherein the array of nanoscopic structures comprise a nanotube coating, the method further comprising directing incident energy from the laser ultrasound testing system into the structure using the nanotube coating.

4. The method of claim 3, wherein the nanotube coating includes nanotubes arranged substantially perpendicular to the scanned surface of the structure.

5. The method of claim 1, further comprising dispersing, with the nanoscopic structures, heat generated by the laser ultrasound testing system on the structure.

6. The method of claim 1, wherein the laser ultrasound testing system is a low power fiber-based laser system.

7. The method of claim 1, further comprising coating the scanned surface with the array of nanoscopic structures.

16. The method of claim 1, wherein the nanoscopic structures disposed on a scanned surface of the structure so as to increase, compared to ultrasonically scanning the structure without the nanoscopic structures disposed on a scanned surface of the structure, a signal to noise ratio when ultrasonically scanning the structure.

17. The method of claim 1, wherein the nanoscopic structures direct about 80% to about 90% of laser energy from the laser ultrasound testing machine into the structure.

18. The method of claim 1, wherein the structure is a composite structure.

19. The method of claim 1, wherein the scanned surface comprises a surface of an aircraft.

8. A method comprising:

disposing a nanotube array on at least a portion of a structure, where the nanotube array is integrally formed on a carrier film by a nanoscopic structure generation module so as to be fixed to and form a unitary member with the carrier film, and the carrier film is affixed to the portion of the structure so that the nanotube array extends away from, so as to be stationarily fixed relative to, the structure;

directing incident energy of a laser ultrasound testing system into the structure in a predetermined direction with the nanotube array and generating a scan of the structure, where the nanotube array includes nanoscopic structures that have respective free ends arranged relative to a surface of the structure so as to extend from the structure and define the predetermined direction, and a pulsed laser beam of the laser ultrasound testing system is moved across the surface of the structure and ultrasonic waves reflected by the structure are detected; and

determining, with the laser ultrasound testing system, if the structure meets a predetermined threshold.

9. The method of claim 8, wherein the nanotube array includes nanotubes arranged substantially perpendicular to the portion of the structure.

10. The method of claim 8, wherein the laser ultrasound testing system is a low power fiber-based laser system.

11. The method of claim 8, further comprising dispersing heat generated by the laser ultrasound testing system on the structure with the nanotube array.

12. A non-destructive evaluation system comprising:

a nanoscopic structure generation module configured to generate an array of nanoscopic structures on a surface of a structure to be evaluated such that nanoscopic structures of the array of nanoscopic structures are formed directly on the structure or on a carrier film that is affixed to the structure so that the nanoscopic structures are integrally formed on the structure or the carrier film that is affixed to the structure and depend from, so as to be stationarily fixed to and form a unitary member with, the structure or the carrier film that is affixed to the structure and respective free ends of the nanoscopic structures of the array of nanoscopic structures extend from the surface in a predetermined directional orientation; and

a laser ultrasound testing system configured to direct incident energy into the structure to be evaluated through the array of nanoscopic structures so that a configuration of the array of nanoscopic structures is configured to direct the incident energy into the structure in a predetermined direction defined by the predetermined directional orientation of the array of nanoscopic structures, and a pulsed laser beam of the laser ultrasound testing system is moved across the surface of the structure and ultrasonic waves reflected by the structure are detected.

13. The non-destructive evaluation system of claim 12, wherein the laser ultrasound testing system comprises a low power fiber-based laser system.

14. The non-destructive evaluation system of claim 12, wherein the nanoscopic structure generation module is configured to generate the array of nanoscopic structures so that nanoscopic structures of the array of nanoscopic structures are arranged substantially perpendicular to the surface.

15. The non-destructive evaluation system of claim 12, wherein the array of nanoscopic structures comprises nanotubes.

20. The system of claim 12, wherein the structure is a composite structure of an aircraft.