STRAIN SENSING DEVICE AND METHOD OF MEASURING STRAIN

• US 20090034903A1
• Filed: 01/31/2007
• Published: 02/05/2009
• Est. Priority Date: 02/01/2006
• Status: Active Grant

• Current Assignee: AFL Telecommunications LLC (Fujikura Limited)
• Original Assignee: AFL Telecommunications LLC (Fujikura Limited)
• Inventors: Herbst, Brian Gerald
• Granted Patent: US 8,111,952 B2
• Time in Patent Office: Days
• US Class Current: 385/13
• CPC Class Codes: G01L 1/242 the material being an optical fibre

Abstract

A strain sensing device has a sub-assembly with at least one optical fiber therein, and a metallic coating encasing the sub-assembly. The metallic coating is strain coupled to the sub-assembly. A strain sensing system and a method of anticipating failure in a structure are provided. The strain sensing system and method of anticipating failure in a structure use the strain on the strain sensing device to calculate the strain on a structure of interest.

Claims

1. A strain sensing device comprising:

a sub-assembly;

at least one optical fiber within the sub-assembly;

a metallic coating which encases the sub-assembly, wherein the metallic coating is strain coupled to the sub-assembly.

2. The strain sensing device of claim 1, wherein an outer diameter of the sub-assembly is greater than an inside diameter of the metallic coating, and the sub-assembly is compressed so as to fit within the metallic coating, whereby strain is translated from the metallic coating to the at least one optical fiber.

3. The strain sensing device of claim 1, wherein an outer diameter of the sub-assembly is equal to an inside diameter of the metallic coating, and the sub-assembly is compressed so as to fit within the metallic coating, whereby strain is translated from the metallic coating to the at least one optical fiber.

4. The strain sensing device of claim 1, wherein an outer diameter of the sub-assembly is smaller than an inside diameter of the metallic coating, and the metallic coating is compressed onto the sub-assembly so as to translate strain from the metallic coating to the at least one optical fiber.

5. The strain sensing device of claim 1, further comprising an expansion agent located between the metallic coating and the least one optical fiber, wherein the expansion agent is activated to strain couple the metallic coating to the at least one optical fiber.

6. The strain sensing device of claim 1, further comprising coupling material between the sub-assembly and the optical fiber.

13. A method of anticipating failure in a structure, comprising the steps of:

attaching the strain sensing device of claim 1 to a structure of interest, wherein the strain of said structure is to be measured;

measuring the strain on the strain sensing device; and

correlating the strain on the device to the strain on the structure.

14. The method of claim 13, wherein the strain on the device is measured along the optical fiber in a length direction.

20. The strain sensing device of claim 1, wherein an initial outer diameter of the sub-assembly is greater than an inside diameter of the metallic coating, and the sub-assembly within the metal coating is in a compressed state.

21. The strain sensing device of claim 1, wherein an initial outer diameter of the sub-assembly is equal to an inside diameter of the metallic coating, and the sub-assembly within the metal coating is in a compressed state.

22. The strain sensing device of claim 1, wherein an outer diameter of the sub-assembly is smaller than an initial inside diameter of the metallic coating, and the metal coating encases the sub-assembly in a compressed state.

7. A strain sensing system comprising:

a strain sensing device comprising,

a sub-assembly;

at least one optical fiber within the sub-assembly;

a metallic coating which encases the sub-assembly, wherein the metallic coating is strain coupled to the sub-assembly;

a structure of interest the strain of which is to be measured, wherein the strain sensing device is connected to said structure; and

a strain measuring system which measures strain in the strain sensing device,

wherein the measured strain on said strain sensing device is used in determining strain on said structure.

8. The strain sensing system of claim 7, wherein the strain sensing device is connected to the structure of interest by the metallic coating.

9. The strain sensing system of claim 7, wherein the strain measuring system eliminates error in strain measurement caused by temperature.

10. The strain sensing system of claim 7, wherein the strain on the device is measured along the at least one optical fiber in a length direction.

11. The strain sensing system of claim 8, wherein the strain on the metallic coating of the strain sensing device is translated to the at least one optical fiber of the strain sensing device.

12. The strain sensing system of claim 7, wherein the strain sensing device further comprises coupling material between the sub-assembly and the at least one optical fiber.

15. A method of making a strain sensing device, comprising:

arranging at least one fiber within a sub-assembly; and

encasing the sub-assembly within a metallic coating, such that the metallic coating is strain coupled to the sub-assembly.

16. The method of claim 15, wherein an outer diameter of the sub-assembly is greater than an inside diameter of the metallic coating, further comprising compressing the sub-assembly to fit within the metallic coating so as to translate strain from the metallic coating to the optical fiber.

17. The method claim 15, wherein an outer diameter of the sub-assembly is equal to an inside diameter of the metallic coating, further comprising compressing the sub-assembly so as to fit within the metallic coating so as to translate strain from the metallic coating to the optical fiber.

18. The method of 15, wherein an outer diameter of the sub-assembly is smaller than an inside diameter of the metallic coating, further comprising compressing the metallic coating onto the sub-assembly so as to translate strain from the metallic coating to the optical fiber.

19. The method of 15, further comprising placing an expansion agent between the metallic coating and the least one optical fiber, and activating the expansion agent to strain couple the metallic coating to the at least one optical fiber.