System and method for evaluating a structure

• US 6,595,684 B1
• Filed: 11/03/1999
• Issued: 07/22/2003
• Est. Priority Date: 11/03/1999
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Casagrande, Louis Gregory, Gilchrist, George William
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Guadalupe, Yaritza
• Application Number:
  US09/433,535
• Time in Patent Office: 1,357 Days
• Field of Search: 374/4, 374/5, 374/6, 374/7
• US Class Current: 374/5
• CPC Class Codes: G01N 25/72 Investigating presence of flaws

Abstract

In a system (10) for evaluating a structure (20), the structure (20) has a predetermined baseline thermal signature. The system (10) includes a thermal source (30) located at least partially inside the structure (20). The thermal source (30) is operable to generate a predetermined amount of heat, which heats the structure (20). The system (10) also includes a detection device (40) that is operable to determine the temperature at various points of the structure (20). The system (10) further includes a computer (50) that is coupled to the detection device (40). The computer (50) is operable to generate a thermal signature of the structure (20) based on the temperature at the various points. The generated thermal signature of the structure (20) is compared to the baseline thermal signature of the structure (20) to determine whether anomalies exist in the structure (20).

Claims

1. A system for evaluating a structure, the system comprising:

a) a structure to be evaluated, the structure having a predetermined baseline thermal signature and formed from a web of interwoven fibers including at least one electrically conductive fiber;

b) a thermal source comprising a power-supply and the at least one electrically conductive fiber, the power supply operable to supply power to the at least one electrically conductive fiber to heat the structure;

c) a detection device operable to detect a thermal energy at various points of the structure; and

d) a computer coupled to the detection device, the computer operable to generate a thermal signature of the structure based on the thermal energy at the various points; and

e) wherein the generated thermal signature of the structure is compared to the baseline thermal signature of the structure to determine whether anomalies exist in the structure.

2. The system of claim 1, wherein the computer is coupled to the power supply and is operable to direct the power supply to produce a steady-state current in the electrically conductive fiber.

3. The system of claim 1, wherein the web of interwoven fibers are coupled to one another with a resin.

4. The system of claim 3, wherein the electrically conductive fiber comprises graphite.

5. The system of claim 1, wherein the electrically conductive fiber is laminated to an interior surface of the structure.

6. The system of claim 1, wherein the electrically conductive fiber has a nonhomogeneous resistance, the nonhomogeneous resistance causing the heat output of the electrically conductive fiber to vary between different locations of the structure.

7. The system of claim 1, wherein the detection device comprises an infrared detection device located outside the structure, the infrared detection device capable of detecting infrared radiation emitted from the structure.

8. The system of claim 1, wherein the detection device comprises a thermocouple located inside the structure.

9. The system of claim 1, wherein the baseline thermal signature is representative of a non-defective structure.

10. The system of claim 1, wherein the computer is further operable to compare the generated thermal signature with the baseline thermal signature.

11. The system of claim 10, wherein the computer is further operable to determine if an anomaly exists in the structure.

12. The system of claim 1, wherein the computer is coupled to the power supply and is operable to direct the power supply to generate a predetermined amount of power to the at least one electrically conductive fiber.

13. The system of claim 1, wherein the at least one electrically conductive fiber is interwoven in a continual looping manner.

14. The system of claim 1, wherein the computer is coupled to the power supply and is -operable to direct the power supply to produce a single pulse current in the electrically conductive fiber.

15. A method for evaluating a structure, the method comprising:

determining an amount of heat to be transferred to the structure;

generating the amount of heat within the structure by directing, by a computer, a power source to deliver a corresponding amount of power to an electrically conductive fiber located at least partially inside the structure;

detecting the thermal energy at various points of the structure;

generating a thermal signature of the structure based on the thermal energy at the various points; and

comparing the generated thermal signature of the structure to a predetermined baseline thermal signature of the structure.

16. The method of claim 15, wherein the electrically conductive fiber comprises graphite and is embedded in the structure.

17. The method of claim 15, wherein detecting the thermal energy at various points of the structure is performed by an infrared detection device located outside the structure, the infrared detection device capable of detecting infrared radiation emitted from the structure.

18. The method of claim 15, wherein detecting the thermal energy at various points of the structure is performed by thermocouples located inside the structure.

19. The method of claim 15, wherein the baseline thermal signature is representative of a non-defective structure.

20. The method of claim 15, further comprising determining whether anomalies exist in the structure.

21. The method of claim 15, further comprising:

varying the amount of heat within the structure over time; and

generating the thermal signature of the structure that varies with time.

22. A system for evaluating a structure, the system comprising:

a structure to be evaluated, the structure formed from a web of interwoven fibers coupled together by a resin;

at least one electrically conductive fiber associated with the web of interwoven fibers;

a power supply coupled to the at least one electrically conductive fiber, the power supply operable to supply power to the at least one electrically conductive fiber to heat the structure;

a detection device operable to detect a thermal energy at various points of the structure; and

a computer coupled to the detection device, the computer operable to generate a thermal signature of the structure based on the thermal energy at the various points.