Systems and methods for inspecting electrical conductivity in composite materials

• US 20070096751A1
• Filed: 11/03/2005
• Published: 05/03/2007
• Est. Priority Date: 11/03/2005
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Georgeson, Gary, Westerman, Everett, Hafenrichter, Joseph
• Granted Patent: US 7,312,608 B2
• Time in Patent Office: Days
• US Class Current: 324/691
• CPC Class Codes: G01N 27/9046 by analysing electrical signals
• CPC Class Codes: G01N 33/442 Resins, plastics
• CPC Class Codes: G01R 27/2623 Measuring-systems or electronic circuits G01R27/2635, G01R27/2682 take precedence

Abstract

Systems and methods for inspecting electrical conductivity in composite materials having conductive structures are disclosed. In one embodiment, a system of inspecting electrical conductivity in an electrical bonding region includes a coil coupled to an alternating current source that is configured to induce a current in a conductive structure within the region. A processor is coupled to the coil that is operable to detect an impedance property value from the coil that results from the current induced in the conductive structure.

Claims

1. A system of inspecting electrical conductivity, comprising:

a conductive bonding region,

a coil coupled to an alternating current source and configured to induce a current in a conductive structure within the region; and

a processor coupled to the coil that is operable to detect at least an impedance property value from the coil that results from the current induced in the conductive structure,

wherein the conductive bonding region further comprises a first fiber-reinforced composite substrate having a first conductive layer, a second fiber-reinforced composite substrate adjacent to the first fiber-reinforced composite substrate and having a second conductive layer, and an intermediate conductive layer that forms an electrically conductive path extending between the first conductive layer and the second conductive layer.

2. The system of claim 1, wherein the alternating current source further comprises a source that is operable to excite the coil at a frequency that ranges between approximately about 50 Hertz (Hz) and approximately about 10 megahertz (MHz).

3. The system of claim 1, wherein the alternating current source further comprises a source that is operable to sequentially excite the coil at more than a single frequency.

4. The system of claim 3, wherein the alternating current source further comprises a source that is operable to generate a selected pair of frequencies, further wherein the selected pair of frequencies have a frequency ratio that ranges between approximately about 2:

1 and approximately about 4;

1.

5. The system of claim 1, wherein the coil further comprises a diameter, and the conductive bonding region further comprises a width, further wherein the diameter is at least approximately equal to the width.

6. The system of claim 1, wherein the detected impedance property value comprises at least one of a resistance, a reactance, a phasor magnitude and a phase angle.

7. The system of claim 1, wherein the coil further comprises a conformable base portion that is configured to be interposed between the coil and the conductive bonding region.

9. The system of claim 1, wherein the first conductive layer, the second conductive layer and the intermediate conductive layer are comprised of at least one of a metallic woven mesh, a metallic foil, a flame sprayed metallic coating, a fabric that is coated with a metallic coating, and a metallic decal.

8. (canceled)

10-22. -22. (canceled)

23. A system for inspecting electrical conductivity in a conductive bonding region, comprising:

a coil assembly including

a coil coupleable to a power source and configured to be positioned proximate a surface of the conductive bonding region, and to induce an eddy current in a conductive portion of the conductive bonding region, and

a conformable base portion positioned between the coil and the surface and configured to conform to a non-planar portion of the surface,

wherein the coil assembly is configured to detect a magnetic field emanated by the eddy current; and

a processor operable to receive a signal indicative of the detected magnetic field from the coil assembly and to compute at least an impedance property value based on the signal.

24. The system of claim 23, wherein the conformable base portion is further configured to maintain the coil at an approximately consistent orientation relative to the surface.

25. The system of claim 24, wherein the conformable base portion includes a first surface configured to abut the coil and a second surface configured to abut the non-planar portion, and a conformable layer disposed between the first and second surfaces.

26. The system of claim 24, wherein the conformable base portion includes

a first surface configured to abut the coil and a second surface positionable proximate the non-planar portion, the second surface having a pair of apertures disposed therein;

and

a pair of leg members at least partially disposed within the apertures and extending outwardly from the second surface, the leg members being configured to abut the surface to maintain the coil at an approximately consistent orientation relative to the surface.

27. The system of claim 23, wherein the coil assembly is further configured to induce an eddy current in a conductive portion of the conductive bonding region that includes at least one composite portion having at least one conductive layer.

28. The system of claim 23, wherein the coil assembly is further configured to induce an eddy current in a conductive portion of the conductive bonding region that includes a first composite portion having a first conductive layer, a second composite portion adjacent to the first composite layer and having a second conductive layer, and an intermediate conductive layer that forms an electrically conductive path extending between the first conductive layer and the second conductive layer.

29. The system of claim 23, further comprising a power source coupled to the coil assembly.