Sensing system for monitoring the structural health of composite structures

• US 20050284232A1
• Filed: 06/24/2005
• Published: 12/29/2005
• Est. Priority Date: 06/25/2004
• Status: Active Grant

• Current Assignee: University of Dayton
• Original Assignee: University of Dayton
• Inventors: Rice, Brian P.
• Granted Patent: US 7,921,727 B2
• Time in Patent Office: Days
• US Class Current: 73/762
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01M 5/0033 by determining damage, crack or wear
• CPC Class Codes: G01M 5/0083 by measuring variation of impedance, e.g. resistance, capacitance, induction
• CPC Class Codes: G01N 27/205 in insulating materials

Abstract

A sensing system for use in monitoring the structural health of a structure such as a polymeric matrix composite structure is provided. The system includes a sensor formed from a conductive ink containing carbon nanofibers and a polymeric resin, and a data acquisition system for acquiring and evaluating data from the sensor. The conductive ink may be applied directly to the structure to be monitored in the form of a grid pattern. Damage to the structure may be detected by measuring changes in resistance values detected from the sensor.

Claims

1. A sensing system for monitoring the structural health of a structure comprising:

a sensor comprising a conductive ink containing carbon nanofibers and at least one polymeric resin; and

a data acquisition system.

2. The system of claim 1 wherein said sensor is applied directly to said structure.

3. The system of claim 1 wherein said data acquisition system comprises electrodes bonded to said sensor.

4. The system of claim 3 wherein said data acquisition system further includes a voltage meter.

5. The system of claim 1 wherein said ink comprises from about 4 to about 12% by weight of carbon nanofibers.

6. The system of claim 1 wherein said sensor is applied in the form of a grid pattern to said structure.

7. The system of claim 1 wherein said structure is selected from a polymeric matrix composite structure, a metal structure, or a concrete structure.

8. The system of claim 6 wherein said structure comprises a polymeric matrix composite structure, and wherein said polymeric resin in said conductive ink is compatible with the polymer in said polymeric matrix composite structure.

9. The system of claim 6 wherein said structure comprises a polymeric matrix composite structure, and wherein said polymeric resin in said conductive ink is the same as the polymer in said polymeric matrix composite structure.

10. The system of claim 1 wherein said at least one polymeric resin is selected from the group consisting of epoxy resins, polyimides, bismaleimides, cyanate esters, polyesters, vinyl esters, and urethanes.

11. A sensing system for monitoring the structural health of a polymeric matrix composite structure comprising:

a sensor comprising a conductive ink containing carbon nanofibers and at least one polymeric resin which is compatible with said polymer in said polymeric matrix composite structure; and

a data acquisition system.

12. A method of monitoring the structural health of a structure comprising:

providing a sensor comprising a conductive ink containing carbon nanofibers and at least one polymeric resin; and

applying said sensor to a structure to be monitored; and

providing a data acquisition system connected to said sensor for acquiring and evaluating data from said sensor.

13. The method of claim 12 wherein said sensor is applied to said structure by painting, rolling or spraying.

14. The method of claim 12 wherein said ink comprises from about 4 to about 12% by weight of said carbon nanofibers.

15. The method of claim 12 wherein said sensor is applied to said structure in the form of a grid pattern.

16. The method of claim 12 wherein said structure is selected from a polymeric matrix composite structure, a metal structure, or a concrete structure.

17. The method of claim 12 wherein said structure comprises a polymeric matrix composite structure, and wherein said polymeric resin in said conductive ink is compatible with the polymer in said polymeric matrix composite structure.

18. The method of claim 12 wherein said structure comprises a polymeric matrix composite structure, and wherein said polymeric resin in said conductive ink is the same as the polymer in said polymeric matrix composite structure.

19. The method of claim 12 wherein said polymeric resin is selected from the group consisting of epoxy resins, polyimides, bismaleimides, cyanate esters, polyesters, vinyl esters, and urethanes.

20. The method of claim 12 wherein said data acquisition system comprises electrodes bonded to said sensor.

21. The method of claim 12 wherein said sensor is applied directly to said structure.

22. The method of claim 12 wherein said structure is electrically conductive.

23. The method of claim 22 including applying a nonconductive insulating coating to said structure prior to applying said sensor.

24. The method of claim 22 including applying a nonconductive insulating coating to said structure prior to applying said sensor.

25. A conductive ink for use in a sensor for monitoring the structural health of a composite structure, said conductive ink comprising from about 4 to about 12% by weight carbon nanofibers and a polymeric resin.

26. The conductive ink of claim 25 wherein said polymeric resin is selected from the group consisting of epoxy resins, polyimides, bismaleimides, cyanate esters, polyesters, vinyl esters, and urethanes.