Sensing system for monitoring the structural health of composite structures
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.
1. A sensing system for monitoring the structural health of a structure comprising:
a sensor comprising a conductive ink containing from about 4 to about 12% by weight vapor grown carbon nanofibers having a high aspect ratio and at least one polymeric resin; and
a data acquisition system; wherein said sensor is applied in the form of a grid pattern directly to the surface of said structure.
2. The system of claim 1 wherein said data acquisition system comprises electrodes bonded to said sensor.
3. The system of claim 2 wherein said data acquisition system further includes a voltage meter.
4. The system of claim 1 wherein said structure is selected from a polymeric matrix composite structure, a metal structure, or a concrete structure.
5. The system of claim 1 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.
6. A sensing system for monitoring the structural health of a polymeric matrix composite structure comprising:
a sensor comprising a conductive ink containing from about 4 to about 12% by weight vapor grown carbon nanofibers having a high aspect ratio and at least one polymeric resin which is compatible with said polymer in said polymeric matrix composite structure; and
a data acquisition system.
7. A method of monitoring the structural health of a structure comprising:
providing a sensor comprising a conductive ink containing from about 4 to about 12% by weight vapor grown carbon nanofibers having a high aspect ratio and at least one polymeric resin; and
applying said sensor to a structure to be monitored in the form of a grid pattern by painting, rolling, or spraying; and
providing a data acquisition system connected to said sensor for acquiring and evaluating data from said sensor.
8. The method of claim 7 wherein said structure is selected from a polymeric matrix composite structure, a metal structure, or a concrete structure.
9. The method of claim 7 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.
10. The method of claim 7 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.
11. The method of claim 7 wherein said polymeric resin is selected from the group consisting of epoxy resins, polyimides, bismaleimides, cyanate esters, polyesters, vinyl esters, and urethanes.
12. The method of claim 7 wherein said data acquisition system comprises electrodes bonded to said sensor.
13. The method of claim 7 wherein said sensor is applied directly to said structure.
14. The method of claim 7 wherein said structure is electrically conductive.
15. The method of claim 14 including applying a nonconductive insulating coating to said structure prior to applying said sensor.