Strain sensing means and methods

• US 20090145239A1
• Filed: 12/11/2007
• Published: 06/11/2009
• Est. Priority Date: 12/11/2007
• Status: Active Grant

• Current Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Original Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Inventors: Shammass, Saeid, Sol, Uri, Girshovich, Simon
• Granted Patent: US 7,913,569 B2
• Time in Patent Office: Days
• US Class Current: 73/779
• CPC Class Codes: G01B 7/16 for measuring the deformation in a solid, e.g. by resistance strain gauge

Abstract

A strain gauge including: a system including a transmission coil, a magnetostrictive material layer and a receiver coil wherein an alternating transmission signal is applied across the transmission coil and an induced signal is induced in the receiver coil, the intensity of the detected signal across the receiver coil being a measurement of strain, wherein frequency of transmission signal is near to a resonance frequency of the system.

Claims

1. A strain gauge for monitoring strain in a substructure, the strain gauge comprising:

a system comprising a transmission coil, a magnetostrictive material layer,, and a receiver coil and a dielectric material sandwiched between the transmission coil and the receiver coil, wherein an alternating transmission signal is applied across the transmission coil and an inducted signal is induced in the receiver coil, the intensity of the detected signal across the receiver coil being a measurement of strain, wherein frequency of transmission signal is near to a resonance frequency of the system.

2. The strain gauge of claim 1, wherein the transmission signal is applied at a set frequency and the intensity of the detected signal is a function of strain.

3. The strain gauge of claim 1, wherein the transmission signal is applied over a range of frequencies and the frequency corresponding to a minimum in the intensity of the detected signal is a function of strain.

4. The strain gauge of claim 1, wherein the magnetostrictive material is sandwiched between the transmission coil and the receiver coil.

5. The strain gauge of claim 1 wherein said strain gauge is embedded in a structural component for measuring the strain of the structural component.

6. The strain gauge of claim 1 being attached to a structural component for measuring the strain of the structural component.

8. The strain gauge of claim 1 wherein the dielectric material comprises a multiplayer composite, and the magnetostrictive material layer is adhered to the dielectric material.

9. The strain gauge of claim 1 wherein the substructure comprises a multiplayer composite and the magnetostrictive material layer is built into the substructure.

10. The strain gauge of claim 1 wherein the substructure comprises a composite material, the magnetostrictive material layer is built into the substructure and monitoring of stress comprises bringing the transmission coil and the receiver coil into proximity with the substructure.

11. The strain gauge of claim 10 wherein the transmission coil and the receiver coil are brought into proximity with the substructure on opposite sides thereof, sandwiching the substructure and magnetostrictive material layer between the transmission coil and the receiver coil.

12. The strain gauge of claim 1 for monitoring strain in a substructure and the strain gauge is adhered to the structure such that strain in the structure causes strain in the magnetostrictive material layer.

7. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. A method of monitoring strain at a location in a structure comprising the steps of:

associating a magnetostrictive material layer to the structure;

bringing a transmission coil into proximity with the structure;

bringing a receiver coil into proximity with the structure;

applying an electrical signal across the transmission coil over a range of frequencies, and

monitoring the frequency corresponding to a minimum detected signal across the receiver coil.

24. The method of claim 23, wherein the magnetostrictive material is sandwiched between the transmission coil and the receiver coil.

25. The method of claim 23, wherein the location is a structural component and at least one of the group consisting of the transmission coil, receiver coil and magnetostrictive material layer are embedded in the structural component for measuring the strain of the structural component.

26. The method of claim 23, wherein the location is a structural component and at least one of the group consisting of the transmission coil, receiver coil and magnetostrictive material layer is attached to the structural component for measuring the strain of the structural component.

27. The method of claim 23, wherein the location is a structural component and the method comprises sandwiching a dielectric material between the transmission coil and the receiver coil.

28. The method of claim 27, wherein the dielectric material comprises a multilayer composite, and the magnetostrictive material layer is adhered to the dielectric material.

29. The method of claim 23, wherein the location is a structural component comprising a multilayer composite and the magnetostrictive material layer is built into the structural component.

30. The method of claim 23, comprising adhering the magnetostrictive material layer to the location.