Detection of thermal damage of composites using molecular probes

Patent metadata

Field	Value
Publication number	US-9671386-B2
Application number	US-201414267718-A
Country	US
Kind code	B2
Filing date	May 1, 2014
Priority date	May 1, 2013
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

Improved methods of detecting thermal exposure are provided herein. The provided methods utilize initially dormant luminescent probes incorporated into a matrix to form a composite. When exposed to heat over a period of time, the luminescent probes are “activated” through a molecular transformation initiated by thermal energy. The activated probes exhibit a luminescent profile based on the extent of thermal exposure, thereby providing an indicator of the thermal exposure experienced by the matrix. When the composite is used to produce a structural component of a vehicle (e.g., an aircraft), the methods provide a convenient, large-area indicator of thermal damage experienced by the structural component.

First claim

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of monitoring thermal exposure of a composite, comprising:
(a) providing a composite, comprising:
(i) a matrix;
(ii) a first probe, wherein the first probe is not luminescent until activated by heat to a temperature above 200° C., after which it becomes luminescent and has a first luminescence profile; and
(iii) a second probe, wherein the second probe is not luminescent until activated by heat, after which it becomes luminescent and has a second luminescence profile that is different from the first luminescence profile;

(b) exposing the composite to a time-temperature profile that includes a portion of time at a temperature above 200° C.; and
(c) measuring an optical property of the composite.

2. The method of claim 1 , wherein the matrix is selected from the group consisting of a thermoset polymer, a thermoplastic polymer, and a sol-gel.

3. The method of claim 1 , wherein the optical property is stimulated emission of the first probe.

4. The method of claim 1 , wherein the first probe is fluorescent or phosphorescent.

5. The method of claim 1 , wherein the matrix is transparent at wavelengths within the first luminescence profile.

6. The method of claim 1 , wherein the first probe is incorporated within the matrix.

7. The method of claim 1 , wherein a coating on the matrix comprises the first probe.

8. The method of claim 1 , wherein the time-temperature profile comprises a rise in temperature from a first temperature to a second temperature between a first time and a second time.

9. The method of claim 8 , wherein the time-temperature profile comprises temperature variations.

10. The method of claim 8 , wherein the time-temperature profile comprises repeated temperature cycles.

11. The method of claim 1 , wherein the first probe and the second probe combine to be a time-temperature indicator of thermal damage.

12. The method of claim 1 , wherein the optical property is the combined stimulated emission of the first probe and the second probe.

13. The method of claim 1 , further comprising a step of analyzing the optical property to determine thermal exposure of the composite.

14. The method of claim 13 , wherein the step of analyzing the optical property comprises comparing the optical property to a calibration data set.

15. The method of claim 1 , wherein the matrix further comprises carbon fibers.

16. The method of claim 15 , wherein the matrix is a carbon-fiber reinforced plastic composite.

17. The method of claim 1 , wherein the composite is a structural component of a vehicle.

18. The method of claim 17 , wherein the composite is a structural component of an aircraft.

Assignees

• Univ Washington Through Its Center For Commercialization

Inventors

• Flinn Brian D
• Jen Alex Kwan-Yue
• Jang Sei-Hum
• Howie Tucker
• Shi Zhengwei

Classifications

• G01N21/71

  thermally excited · CPC title

• G01N21/643

  non-biological material · CPC title

• G01N33/442 Primary

  Resins; Plastics · CPC title

• G01K11/20

  using thermoluminescent materials (G01K11/32 takes precedence) · CPC title