Inspection of non-planar parts using multifrequency eddy current with phase analysis

• US 20060202687A1
• Filed: 01/12/2006
• Published: 09/14/2006
• Est. Priority Date: 03/09/2005
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Wang, Changting, Suh, Ui
• Granted Patent: US 7,518,359 B2
• Time in Patent Office: Days
• US Class Current: 324/238
• CPC Class Codes: G01N 27/9046 by analysing electrical signals
• CPC Class Codes: G01N 27/9086 Calibrating of recording device

Abstract

A non-planar part has a non-planar surface such as an edge, and may contain an anomaly such as a crack. The non-planar part is inspected using an eddy current technique. The method includes providing the non-planar part having the non-planar surface thereon, driving an eddy current probe at two or more frequencies, measuring an eddy current response signal of the non-planar part at each frequency, and performing a multifrequency phase analysis on the eddy current response signals.

Claims

1. A method for inspecting a non-planar part using an eddy current technique, comprising the steps of

providing the non-planar part;

driving an eddy current probe at two or more frequencies;

measuring an eddy current response signal of the non-planar part at each frequency; and

performing a multifrequency phase analysis on the eddy current response signals.

2. The method of claim 1, wherein the step of providing includes the step of

providing the non-planar part having an anomaly therein.

3. The method of claim 1, wherein the step of providing includes the step of

providing the non-planar part having a crack therein.

4. The method of claim 1, wherein the step of providing includes the steps of

providing the non-planar part having an anomaly therein, and

providing the non-planar part having a non-planar surface thereon, and wherein the anomaly is at or near the non-planar surface.

5. The method of claim 1, wherein the step of providing includes the step of

providing the non-planar part having a crack therein intersecting an edge.

6. The method of claim 1, including an additional step of

scanning the eddy current probe over the non-planar part.

7. The method of claim 1, wherein the step of performing includes the steps of

mixing the eddy current response signals of the two or more frequencies to form a mixed signal,

level shifting a real component of the mixed signal to confine the phase of the mixed signal to the range between −

180 and +180 degrees, and

obtaining phase and magnitude images of the non-planar part.

8. A method for inspecting a non-planar part using an eddy current technique, comprising the steps of

providing the non-planar part having an edge thereon;

driving an eddy current probe at two or more frequencies;

scanning the eddy current probe over the non-planar part;

measuring an eddy current response signal of the non-planar part at each frequency; and

performing a multifrequency phase analysis on the eddy current response signals, wherein the step of performing includes the steps of

mixing the eddy current response signals of the two or more frequencies to form a mixed signal,

level shifting a real component of the mixed signal to confine the phase of the mixed signal to the range between −

180 and +180 degrees, and

obtaining phase and magnitude images of the non-planar part.

9. The method of claim 8, wherein the step of providing includes the step of

providing the non-planar part having an anomaly therein.

10. The method of claim 8, wherein the step of providing includes the step of

providing the non-planar part having a crack therein.

11. The method of claim 8, wherein the step of providing includes the steps of

providing the non-planar part having an anomaly therein, and

providing the non-planar part having a non-planar surface thereon, and wherein the anomaly is at or near the non-planar surface.

12. The method of claim 8, wherein the step of providing includes the step of

providing the non-planar part having a crack therein intersecting the edge.

13. The method of claim 8, including an additional step of

scanning the eddy current probe over the non-planar part.

14. The method of claim 8, wherein the step of performing includes the steps of

mixing the eddy current response signals of the two or more frequencies to form a mixed signal,

level shifting a real component of the mixed signal to confine the phase of the mixed signal to the range between −

180 and +180 degrees, and

obtaining phase and magnitude images of the non-planar part.

15. An inspection system operable to inspect a non-planar part for a possible crack therein, comprising:

an eddy current probe operable to induce eddy currents of at least two different frequencies in the non-planar part;

an eddy current instrument coupled to the eddy current probe, wherein the eddy current instrument is configured to apply a plurality of multifrequency excitation signals to the eddy current probe to generate a plurality of multifrequency response signals from the non-planar part; and

a processor configured to analyze the multifrequency response signals from the eddy current instrument by performing a multifrequency phase analysis, to inspect the non-planar part for the presence of the crack.