Damage detection system for structural composite material and method of detecting damage to structural composite material

• US 7,176,448 B2
• Filed: 09/23/2004
• Issued: 02/13/2007
• Est. Priority Date: 09/26/2003
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Jukogyo KK (Subaru Corp.)
• Inventors: Ogisu, Toshimichi, Takeda, Nobuo, Shimanuki, Masakazu
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US10/947,312
• Publication Number:
  US 20050067559A1
• Time in Patent Office: 873 Days
• Field of Search: 250/227.14, 250/227.16
• US Class Current: 250/227.14
• CPC Class Codes: G01M 11/086 Details about the embedment of the optical fiber within the DUT
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 2291/048 Transmission, i.e. analysed material between transmitter and receiver
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves

Abstract

Damage caused to a structural composite material is detected while reduction in the strength thereof is prevented. A damage detection system 10 for a structural composite material includes a vibration application apparatus 20 including: a sheet body 22; a plurality of piezo elements 21 sprinkled throughout and held by the sheet body 22; and wires 23 for the piezo elements 21 provided to the sheet body 22. The damage detection system 10 also includes: a fiber optic sensor 30 which includes a grating portion 33 in a core portion 32 thereof, the grating portion 33 reflecting light of a predetermined wavelength; a light source to perform light irradiation onto the core portion 32; and a characteristic detection unit 42 to detect a characteristic of the light reflected from the grating portion 33.

Claims

1. A damage detection system for a structural composite material, comprising:

a piezo element;

a fiber optic sensor which includes a grating portion in a core portion thereof, the grating portion configured to reflect light of a predetermined wavelength;

a light source configured to perform light irradiation onto the core portion; and

a characteristic detection unit configured to detect a characteristic of the light reflected from the grating portion,

wherein the structural composite material includes a plurality of members that are joined to each other at a joining portion, and

wherein the fiber optic sensor is placed in the joining portion so as to be sandwiched between the members.

2. The damage detection system as claimed in claim 1, wherein the piezo element is disposed in a vicinity of the joining portion.

3. The damage detection system as claimed in claim 2, wherein the piezo element and the fiber optic sensor are disposed such that one of the members is placed therebetween.

20. The damage detection system as claimed in claim 1, wherein the piezo element is installed such that a vibration propagation path from the piezo element to the grating portion passes through the joining portion.

22. The damage detection system as claimed in claim 1,

wherein the piezo element is disposed on a first surface of the structural composite material, and

wherein the fiber optic sensor is disposed on a second surface of the structural composite material different from the first surface.

26. The damage detection system as claimed in claim 22, wherein the first and second surfaces are opposite surfaces of the structural composite material.

4. A damage detection method for a structural composite material, comprising

providing:

the structural composite material comprising a plurality of members that are joined to each other at a joining portion,

a piezo element fixedly disposed at a vicinity of the joining portion,

a lead wire which transmits a signal to the piezo elements,

a fiber optic sensor which is fixedly disposed in the joining portion so as to be sandwiched between the members and includes a grating portion in a core portion, the grating portion reflecting light of a predetermined wavelength,

a light source which performs light irradiation onto the core portion, and

a characteristic detection unit which detects a characteristic of the light reflected from the grating portion;

applying vibration to the structural composite material by using the piezo element; and

detecting damage based on a change in an output from the characteristic detection unit.

23. The method as claimed in claim 4, wherein the providing step further comprises:

disposing the piezo element on a first surface of the structural composite material; and

disposing the fiber optic sensor on a second surface of the structural composite material different from the first surface.

27. The method as claimed in claim 23, wherein the first and second surfaces are opposite surfaces of the structural composite material.

5. A damage detection system for a structural composite material, comprising:

a vibration application apparatus configured to apply vibration to the structural composite material;

a fiber optic sensor which includes a grating portion in a core portion thereof, the grating portion configured to reflect light of a predetermined wavelength;

a light source to configured to perform light irradiation onto the core portion; and

a characteristic detection unit configured to detect a characteristic of the light reflected from the grating portion,

wherein the vibration application apparatus comprises a plurality of piezo elements,

wherein the structural composite material includes a plurality of members that are joined to each other at a joining portion, and

wherein the fiber optic sensor is placed in the joining portion so as to be sandwiched between the members.

6. The damage detection system as claimed in claim 5, wherein the vibration application apparatus further comprises:

a sheet body, wherein the plurality of piezo elements are sprinkled throughout and held by the sheet body; and

a plurality of wires for the piezo elements provided to the sheet body.

7. The damage detection system as claimed in claim 6, wherein the sheet body has flexibility and deformability.

8. The damage detection system as claimed in claim 5, wherein the fiber optic sensor has an outer diameter of 50 to 100 μ

m.

9. The damage detection system as claimed in claim 5, wherein the fiber optic sensor has an outer diameter of less than 50 μ

m.

10. The damage detection system as claimed in claim 5, wherein vibration applied from the vibration application apparatus is transmitted to the fiber optic sensor through the structural composite material.

11. The damage detection system as claimed in claim 10, wherein the vibration applied from the vibration application apparatus is instantaneous vibration.

12. The damage detection system as claimed in claim 5, wherein the vibration application apparatus is provided on the surface of the structural composite material.

13. The damage detection system as claimed in claim 12, wherein the vibration application apparatus is provided by adhesion or bonding.

14. The damage detection system as claimed in claim 5, wherein the fiber optic sensor is provided inside a hollow in the structural composite material.

15. The damage detection system as claimed in claim 5, wherein the structural composite material includes a plurality of members which are joined to each other at a joining portion, and the vibration application apparatus and the fiber optic sensor are disposed in or in the vicinity of the joining portion.

16. The damage detection system as claimed in claim 15, wherein the fiber optic sensor is placed in the joining portion so as to be sandwiched between the members, or embedded in one of the members so as to be placed in the vicinity of the joining portion.

17. The damage detection system as claimed in claim 15, wherein the vibration application apparatus and the fiber optic sensor are disposed such that one of the members is placed therebetween.

24. The damage detection system as claimed in claim 12, wherein the fiber optic sensor is provided on a surface of the structural composite material that is different from the surface of the structural composite material on which the vibration application apparatus is provided.

28. The damage detection system as claimed in claim 24, wherein the surface on which the fiber optic sensor is provided and the surface on which the vibration application apparatus is provided are opposite surfaces of the structural composite material.

18. A damage detection system for a structural composite material, comprising:

a piezo element;

a fiber optic sensor which includes a grating portion in a core portion thereof, the grating portion configured to reflect light of a predetermined wavelength;

a light source configured to perform light irradiation onto the core portion; and

a characteristic detection unit configured to detect a characteristic of the light reflected from the grating portion,

wherein the structural composite material includes a plurality of members that are joined to each other at a joining portion, and

wherein the fiber optic sensor is embedded in one of the members so as to be placed in a vicinity of the joining portion.

19. The damage detection system as claimed in claim 18, wherein the piezo element is disposed in the vicinity of the joining portion.

21. The damage detection system as claimed in claim 18, wherein the piezo element is installed such that a vibration propagation path from the piezo element to the grating portion passes through the joining portion.

25. The damage detection system as claimed in claim 18,

wherein the piezo element is disposed on a first surface of the structural composite material, and

wherein the fiber optic sensor is disposed on a second surface of the structural composite material different from the first surface.

29. The damage detection system as claimed in claim 25, wherein the first and second surfaces are opposite surfaces of the structural composite material.