GB2456583A - Eddy current inspection system and method of eddy current flaw detection - Google Patents
Eddy current inspection system and method of eddy current flaw detection Download PDFInfo
- Publication number
- GB2456583A GB2456583A GB0801102A GB0801102A GB2456583A GB 2456583 A GB2456583 A GB 2456583A GB 0801102 A GB0801102 A GB 0801102A GB 0801102 A GB0801102 A GB 0801102A GB 2456583 A GB2456583 A GB 2456583A
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- GB
- United Kingdom
- Prior art keywords
- probe
- detection circuit
- eddy current
- detection
- flaw
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
- G01N27/9013—Arrangements for scanning
- G01N27/902—Arrangements for scanning by moving the sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
- G01B7/04—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
Abstract
An eddy current inspection system 10 is disclosed for detection of linear flaws 1 in conductive materials. The eddy current inspection system 10 comprises a probe 11, a first detection circuit 12, a second detection circuit 13 and an indicator 14 for indicating the detection of a flaw 1. The probe has a sensitivity that varies depending upon the relative orientation between an axis of the probe 11 and the direction of a linear flaw 1. The first detection circuit 12 is arranged to be connected to the probe 11 with the first detection circuit 12 producing a sensitivity function that varies with the orientation angle between an axis of the probe and the direction of a linear flaw. The second detection circuit 13 produces a sensitivity function having peaks at a different orientation angle between an axis of the probe and the direction of a linear flaw from the first detection circuit. The use of two detection circuits that produce sensitivity functions with peaks at different relative orientation angles between an axis of the probe and the direction of a linear flaw enables flaws in more than one direction to be detected simultaneously, reducing the amount of repeated scanning required and increasing the likelihood of detecting a flaw regardless of its orientation.
Description
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1
2456583
EDDY CURRENT INSPECTION SYSTEM AND METHOD OF EDDY CURRENT FLAW DETECTION
The present invention relates generally to eddy current inspection and, more specifically, to eddy current probes for non-destructive testing of conductive materials.
Eddy current inspection is a commonly used technique for non-destructive testing of conductive materials for surface flaws. Eddy current inspection is based on the principle of electromagnetic induction, wherein a drive coil carrying currents induces eddy currents within a test specimen, by virtue of generating a primary magnetic field. The eddy currents so induced in turn generate a secondary magnetic field, which induces a potential difference in the sense coils, thereby generating signals, which may be further analysed for flaw detection. In the case of a flaw in the test specimen, as for example, a crack or a discontinuity, the eddy current flow within the test specimen alters, thereby altering the signals induced in the sense coils. This deviation in the signals is used to indicate the flaw.
Many probes, such as a so-called "Weldscan" probe, have a sensitivity that varies dependent upon the relative orientation between an axis of the probe and the direction of a linear or elongate flaw such as a crack or discontinuity. For example, when a Weldscan probe is connected to a bridge detection circuit as disclosed in US-A-5 237 271, the probe and detection circuit are most sensitive to elongate cracks or discontinuities in line with or perpendicular to an axis of the probe.
However, the eddy current probes described above are limited by the fact that a prior knowledge of crack orientation is required. Due to this directionality of different eddy current probes, if more than one flaw orientation is anticipated, the test specimen must be repeatedly scanned in different orientations to detect the flaws. The repeated scanning makes this process laborious and time consuming.
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It would be desirable to have an eddy current inspection system that is able to detect cracks and other linear flaws with random orientations without having to repeatedly scan with the probe in different orientations.
According to a first aspect of the present invention there is provided an eddy current inspection system for detection of linear flaws in conductive materials, the eddy current inspection system comprising a probe having a sensitivity that varies depending upon the relative orientation between an axis of the probe and the direction of a linear flaw;
a first detection circuit arranged to be connected to the probe, the first detection circuit producing a sensitivity function that varies with the orientation angle between an axis of the probe and the direction of a linear flaw;
a second detection circuit arranged to be connected to the probe, the second detection circuit producing a sensitivity function having peaks or more sensitive regions at different orientation angles between an axis of the probe and the direction of a linear flaw from the first detection circuit and an indicator for indicating the detection of a flaw.
The use of two detection circuits that produce sensitivity functions with peaks or more sensitive regions at different relative orientation angles between an axis of the probe and the direction of a linear flaw enables flaws in more than one direction to be detected simultaneously, reducing the amount of repeated scanning required and increasing the likelihood of detecting a flaw regardless of its orientation.
The sensitivity function of the second detection circuit preferably has peaks positioned substantially 45° from the peaks of the sensitivity function of the first detection circuit. Thus peak sensitivities are achieved not only when the probe is in line with or perpendicular to a linear flaw but also at angles half way therebetween significantly increasing the likelihood of successfully detecting a linear flaw, regardless of its orientation relative to the probe.
The sensitivity function may be a substantially sinusoidal function.
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The indicator may be arranged to combine outputs from both the first and the second detection circuits to provide a visual indication of the detection of a flaw.
According to a second aspect of the present invention there is provided a method of operating an eddy current inspection system for detection of linear flaws in conductive materials, the method comprising passing a probe having a sensitivity that varies depending upon the relative orientation between an axis of the probe and the direction of a linear flaw over the surface of a conductive material to be tested;
connecting a first detection circuit to the probe, the first detection circuit producing a sensitivity function that varies with the orientation angle between an axis of the probe and the direction of the linear flaw;
connecting a second detection circuit to the probe, the second detection circuit producing a sensitivity function having peaks or more sensitive regions at different orientation angles between an axis of the probe and the direction of a linear flaw from the first detection circuit and indicating when a flaw is detected.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 schematically shows a current inspection system according to a first embodiment of the present invention for detection of linear or elongate flaws in conductive materials;
Figure 2 shows a perspective view of a probe that may be used in the inspection system of an embodiment of the present invention;
Figure 3 shows a top view of the probe shown in Figure 2;
Figure 4 schematically shows a circuit diagram of a detection circuit;
Figure 5 shows a sensitivity function of the detection circuit shown in Figure 4;
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Figure 6 shows another detection circuit;
Figure 7 shows a sensitivity function produced by the detection circuit of Figure 6;
Figure 8 shows the combined sensitivity functions of the detection circuits shown in Figures 4 and 6;
Figure 9 illustrates a viewing screen with a trace showing the detection of a flaw;
Figure 10 is a table showing the magnitude of traces detected by the detection circuits shown in Figures 4 and 6 at different orientation angles between an axis of a probe and the direction of a linear flaw and also shows combined detection traces produced from a combination of the detection traces from both detection circuits shown in Figures 4 and 6;
Figure 11 illustrates a method of displaying the combined signal produced by the detection circuits shown in Figures 4 and 6 and
Figures 12 to 14 illustrate alternative probe and detection circuit arrangements that may be used in embodiments of the present invention.
Figure 1 illustrates a first embodiment of an eddy current inspection system 10 for detecting linear flaws in conductive materials. A linear or elongate flaw 1 is shown in a conductive material which could for example be an aircraft panel, an oil and gas pipeline, a fairground ride component, a portion of the body of a submarine, a railway axle or any conductive material which requires inspection to confirm its worthiness.
The inspection system 10 has a probe 11, the sensitivity of which varies depending upon the relative orientation between an axis of the probe and the direction of the linear flaw. A first detection circuit 12 and a second detection
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circuit 13 are arranged to be connected to the probe 11. The first detection circuit 12 produces a sensitivity function that varies with the orientation angle between an axis of the probe and the direction of the linear flaw 1. The second detection circuit 13 also produces a sensitivity function that varies with the orientation angle between an axis of the probe and the direction of a linear flaw, except that the sensitivity function of the second detection circuit 13 has peaks or more sensitive regions at a different orientation angle between an axis of the probe and the direction of a linear flaw from the first detection circuit 12. The peaks produced by the first and second detection circuits are preferably substantially 45° apart. However, the precise angular difference in peak positions between the sensitivity functions of the first and second detection circuits 12, 13 will of course depend upon the precision of electrical components and other factors and may be between, for example 25° and 65° or between 35° and 55° for example. The detection circuits 12, 13 are connected to an indicator 14 for indicating to an operator the detection of a flaw 1 as the probe 11 of the inspection system 10 is passed over a flaw 1 as shown by the arrow 15. As the two detection circuits 12, 13 have sensitivity functions with peaks at different relative orientation angles between an axis of the probe 11 and the direction of a linear flaw 1, flaws in more than one direction may be detected simultaneously by the inspection system 10 increasing the likelihood of detecting a flaw regardless of its orientation.
Figure 2 shows a perspective view of a probe having a sensitivity that varies depending upon the relative orientation between an axis of the probe and the direction of a linear flaw as in embodiments of the present invention. The probe comprises two coils arranged vertically in the view of Figure 2 and intersecting at their upper and lower points and with the sides of one coil 20 separated by 90° from the sides of the other coil 21.
Figure 3 shows a top view of the probe 11 shown in Figure 2 with each of the coils 20, 21 clearly seen being substantially 90° apart when viewed from above. The coil illustrated in Figures 2 and 3 is known as a "Weldscan" probe.
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In use the probe 11 is scanned over a conductive surface in the direction shown by the arrow 15 in Figure 2. Because of the construction of the probe 11, having the two coils 20, 21, the probe 11 has greatest sensitivity when connected in the differential electrical bridge (see fig 4) in direction orthogonal with the coils 20, 21 with less or no sensitivity there between. As the coils are differentially connected then the response indicated for coil 20 for a flaw orthogonal to the coil is opposite in sign to that for coil 21.
Figure 4 shows a detection circuit 12 as may be used with the inspection system 10 of the present invention. The detection circuit comprises an electrical "bridge" with the two coils 20, 21 forming two arms of the bridge and two resistors 40, 41 forming the two other arms of the bridge. The bridge is driven by an oscillating current source 42 and an output 44 is provided by an amplifier 43 connected to the two arms of the bridge.
Figure 5 if a graph showing the sensitivity detected by the probe 11 when passed through the detection circuit 12 at various angles between a probe axis and the direction of a linear flaw. As can be seen from Figure 5, the detection circuit 12 shown in Figure 4 has greatest sensitivity at 0°, 90°, 180°, 270° etc angles between the probe axis and a direction of a linear flaw. As can also be seen from Figure 5, the probe 11 when connected to first detection circuit 12 shown in Figure 4 has little or no sensitivity at angles of 45°, 135° etc between the probe axis and the direction of a linear flaw.
Figure 6 shows a circuit diagram of a second detection circuit 13 arranged to be used in an eddy current inspection system 10 of an embodiment of the present invention. This circuit is known as a "reflection" circuit and is driven by oscillating current source 61 and includes the two coils 20, 21 of the probe 11 and an output amplifier 62 providing an output signal 63.
Figure 7 shows a sensitivity function of the output of the probe 11 passed through the second detection circuit 13 with the sensitivity varying dependent upon the angle between the axis of the probe 11 and the direction of the linear flaw. As can be seen from Figure 7, the greatest sensitivity of the second
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detection circuit is at angles of 45°, 135°, 225° etc between the probe axis and the direction of a linear flaw. As can also be seen from Figure 7, the detection circuit of Figure 6 has little or no sensitivity at angles of 0°, 90°, 180° etc between the probe axis and the direction of a linear flaw.
Figure 8 shows a sensitivity function produced by a combination of the first and second detection circuits 12, 13. As can be seen, at every angle between the probe axis and the direction of a linear flaw at least one of the detection circuits 12, 13 has a sensitivity greater than half the maximum sensitivity. Thus, as can be seen, by combining outputs from two detection circuits which produce sensitivity peaks at different angles between the probe axis and the direction of a linear flaw, flaws may be detected at a far greater number of relative orientations than when only a single detection circuit is used.
Figure 9 shows a user display 90 to be used by an operator of the interface device 10 to indicate the detection of a flaw. In this example, the interface device is arranged to display traces corresponding to detection of a flaw by either or both of the detection circuits 12,13. In the example shown in Figure 9, a trace 91 detected by detection circuit 12 is indicated whilst no appreciable detection signal is produced by the trace 92 corresponding to detection circuit 13. As the display unit 90 is arranged to display two traces 91, 92, each corresponding to one of the first and second detection circuits 12, 13, the eddy current inspection system 10 is able to detect the presence of flaws at far more orientations relative to the probe 11 than when used with only a single detection circuit. Furthermore, by analysis of the sizes and directions of the two traces produced when a flaw is detected, one may ascertain information regarding the orientation of the flaw relative to the probe. For example, the two traces 91, 92 shown in Figure 9 indicate a large or peak detection by detection circuit 12 and a substantially zero detection by second detection circuit 13. By referring to the combined sensitivity function shown in Figure 8, one may determine that the linear flaw is in line with or has a zero 0 angle between an axis of the probe and the direction of the linear flaw. Thus, use of the two detection circuits, with peak sensitivities at different angles between the probe axis and the direction of a linear flaw not only enables
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flaws at more angles relative to the probe to be detected, but also enables information regarding the orientation of the flaw relative to the probe to be determined. In the user display 90 shown in Figure 9, markings 93 are also provided to indicate the zero or "home" position of a trace when no flaw is detected.
Figure 10 is a table indicating for various angles between the probe axis and the direction of a linear flaw the appearance of a trace and the amplitude of the trace obtained from the first detection circuit 12 and from the second detection circuit 13 at various angles at intervals of 22.5°. As discussed with regard to the trace shown in Figure 9, and as can be seen by the traces obtained from the first detection circuit 12 and the second detection circuit 13, analysis of the size and sign of the traces produced for each detection circuit 12, 13 can provide information regarding the direction of the flaw relative to the axis of the probe.
The last two rows of the table of Figure 10 illustrate a novel manner of providing the information supplied by the two traces from the first and second detection circuits 12,13. In the example of the last two rows of Figure 10, the two traces from the first and second detection circuits 12, 13 are combined. The traces may be combined in any suitable manner. However, in the example of the last two lines of the table of Figure 10, the trace from one detection circuit is plotted vertically whilst the trace from the other detection circuit is plotted horizontally to arrive at a combined trace in which the direction of the trace is indicative of the angle between an axis of the probe and the direction of the linear flaw. Furthermore, as can be seen from the last line of the table of Figure 10, the amplitudes of each of the combined traces are substantially the same size such that as well as the direction of the combined trace providing information as to the direction of a detected flaw relative to the orientation of the probe axis, the amplitude of a trace can also be used to be indicative of the size of a detected flaw.
Figure 11 is a plot of the trace from the last two lines of the table of Figure 10 obtained from a combination of the first and second detection circuits 12, 13.
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As can be seen from Figure 11, which may represent a user interface device or screen 90, the direction of a detected trace from the centre is indicative of the orientation angle between an axis of the probe and the direction of a linear flaw. Furthermore, the length of a trace may be proportional to the depth of a detected flaw. Thus considerably more information is presented to a user than with a prior eddy current probe detector.
The eddy current inspection system 10 of embodiments of the present invention may be used with any probe having a sensitivity that varies depending upon the relative orientation between an axis of the probe and the direction of a linear flaw. As well as the "Weldscan" probe described in Figures 2 and 3 and the bridge detection circuit and reflection detection circuit shown in Figures 4 and 6 respectively, various other probes and detection circuits may be used in embodiments of the present invention as explained for example with reference to Figures 12,13 and 14.
Figure 12 shows four coils labelled A, B, C and D arranged in a probe adjacent to each other with each coil in the same plane. Figure 12 also shows the four coils A, B, C and D connected together in first and second bridge circuits 101, 102.
Figure 13 shows a probe 11 similar to that used in Figure 12 except also including a further drive coil arranged around the four coils A, B, C and D. As shown in Figure 13, the drive coil and coils A, B, C and D, may be connected in reflection circuits 111, 112.
The probe 11 may have solid state sensors rather than coils as described above as shown schematically in Figure 14 with the probe 11 being shown with four directional solid state sensors A1, B1. C1 and D1 and with a drive coil arranged around the four directional solid state sensors.
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The solid state sensors may be connected using bridge or reflection circuits or both as described above and are illustrated in Figure 14 with two reflection circuits 121,122.
The first and second detection circuits may be connected to the probe in any suitable manner as is well known to the person skilled in the art. For example, each of the detection circuits 12, 13, may be provided separately and each connected to coils or solid state sensors provided in the probe 11. Alternatively, the two detection circuits may share some components and may be switched between operation as a first detection circuit 12 or a second detection circuit 13. Signals from the first and second detection circuits may be sampled for a period of time one after another. For example, the output of the first and second detection circuits may be sampled alternately for example for only a few micro or milli seconds each.
A particular probe may be determined to have any suitable axis, provided that the same axis is used for both detection circuits. If desired, a probe may be calibrated upon first use with linear flaws of a known direction in order to determine the direction of the axis of the probe 11.
Although the invention has been described above with regard to specific examples, many variations may be made to the examples described above without departing from the scope of the invention. For example any probe having a sensitivity that varies depending upon the relative orientation between an axis of the probe and the direction of a linear flaw may be used. Furthermore, the probe may be connected to any two or more detection circuits that have sensitivity functions with peaks or more sensitive regions at different orientation angles between an axis of the probe and the direction of a linear flaw. Moreover, any type of indicator for indicating the detection of a flaw may be used such as a display or the production of an audible sound.
Although the embodiments described in the accompanying drawings have used two detection circuits 12, 13 sensitive at different relative orientation angles, any number of two or more detection circuits sensitive at different
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relative orientation angles may be used. The detection circuits could have more sensitive regions or peaks substantially equidistantly spaced apart. For example, three detection circuits may be used. The three detection circuits could have more sensitive regions or peaks positioned substantially 30° apart.
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Claims (12)
1. An eddy current inspection system for detection of linear flaws in conductive materials, the eddy current inspection system comprising a probe having a sensitivity that varies depending upon the relative orientation between an axis of the probe and the direction of a linear flaw;
a first detection circuit arranged to be connected to the probe, the first detection circuit producing a sensitivity function that varies with the orientation angle between an axis of the probe and the direction of a linear flaw;
a second detection circuit arranged to be connected to the probe, the second detection circuit producing a sensitivity function having peaks or more sensitive regions at different orientation angles between an axis of the probe and the direction of a linear flaw from the first detection circuit and an indicator for indicating the detection of a flaw.
2 An eddy current inspection system according to claim 1, wherein the peaks or more sensitive regions produced by the detection circuits are spaced apart substantially equidistantly.
3. An eddy current inspection system according to claim 1 or claim 2, when used with two detection circuits wherein the peaks or more sensitive regions produced by the second detection circuit are positioned between 25° and 65° from the peaks or more sensitive regions of the first detection circuit.
4. An eddy current inspection system according to claim 3, wherein the peaks or more sensitive regions produced by the second detection circuit are positioned substantially 45° from the peaks or more sensitive regions of the first detection circuit.
5. An eddy current inspection system according to any one of the preceding claims, wherein the indicator for indicating the detection of a flaw is a visual display.
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6 An eddy current inspection system according to claim 5, wherein the visual display is arranged to provide two traces, one produced by each of the first and second detection circuits.
7. An eddy current inspection system according to claim 5, wherein the visual display is arranged to produce a single trace produced from a combination of both the first and second detection circuits.
8. An eddy current inspection system according to claim 7, wherein the single trace is produced from a combination of an output from the first detection circuit in one direction and an output from the second detection circuit in the substantially perpendicular direction with the two outputs combined to produce a single output trace.
9. An eddy current inspection system according to any one of the preceding claims, having more than two detection circuits, each having sensitivity functions with peaks or more sensitive regions at different orientation angles between an axis of the probe and the direction of a linear flow.
10. A method of operating an eddy current inspection system for detection of linear flaws in conductive materials, the method comprising passing a probe having a sensitivity that varies depending upon the relative orientation between an axis of the probe and the direction of a linear flaw over the surface of a conductive material to be tested;
connecting a first detection circuit to the probe, the first detection circuit producing a sensitivity function that varies with the orientation angle between an axis of the probe and the direction of the linear flaw;
connecting a second detection circuit to the probe, the second detection circuit producing a sensitivity function having peaks or more sensitive regions at different orientation angles between an axis of the probe and the direction of a linear flaw from the first detection circuit and indicating when a flaw is detected.
14
11. An eddy current inspection system substantially as hereinbefore described with reference to the accompanying drawings.
12. A method of operating an eddy current inspection system substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0801102A GB2456583B (en) | 2008-01-21 | 2008-01-21 | Eddy current inspection system and method of eddy current flaw detection |
| PCT/GB2009/050048 WO2009093070A1 (en) | 2008-01-21 | 2009-01-21 | Eddy current inspection system and method of eddy current flaw detection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0801102A GB2456583B (en) | 2008-01-21 | 2008-01-21 | Eddy current inspection system and method of eddy current flaw detection |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0801102D0 GB0801102D0 (en) | 2008-02-27 |
| GB2456583A true GB2456583A (en) | 2009-07-22 |
| GB2456583B GB2456583B (en) | 2012-09-05 |
Family
ID=39166128
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0801102A Expired - Fee Related GB2456583B (en) | 2008-01-21 | 2008-01-21 | Eddy current inspection system and method of eddy current flaw detection |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2456583B (en) |
| WO (1) | WO2009093070A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120025816A1 (en) * | 2010-07-30 | 2012-02-02 | Olympus Ndt Inc. | Orthogonal eddy current probe for multi-directional inspection |
| EP2843400A1 (en) * | 2013-09-03 | 2015-03-04 | Siemens Aktiengesellschaft | Sensor assembly and method for determining mechanical surface tensions and/or microstructure |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8212553B2 (en) | 2009-12-21 | 2012-07-03 | Westinghouse Electric Company Llc | Inspection mode switching circuit |
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| WO1984004596A1 (en) * | 1983-05-16 | 1984-11-22 | Toernbloms Kvalitetskontroll | Method and apparatus for testing using a plurality of frequencies |
| US4799010A (en) * | 1984-09-20 | 1989-01-17 | Institut De Recherches De La Siderurgie Francaise | Process for detecting defects on a surface by eddy currents and device for carrying out said process |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20120025816A1 (en) * | 2010-07-30 | 2012-02-02 | Olympus Ndt Inc. | Orthogonal eddy current probe for multi-directional inspection |
| CN102375027A (en) * | 2010-07-30 | 2012-03-14 | 奥林巴斯Ndt公司 | Eddy current system of orthogonal eddy current probe for multi-directional inspection |
| US8519702B2 (en) * | 2010-07-30 | 2013-08-27 | Olympus Ndt Inc. | Orthogonal eddy current probe for multi-directional inspection |
| CN102375027B (en) * | 2010-07-30 | 2014-08-13 | 奥林巴斯Ndt公司 | Eddy current system of orthogonal eddy current probe for multi-directional inspection |
| EP2843400A1 (en) * | 2013-09-03 | 2015-03-04 | Siemens Aktiengesellschaft | Sensor assembly and method for determining mechanical surface tensions and/or microstructure |
| WO2015032638A1 (en) * | 2013-09-03 | 2015-03-12 | Siemens Aktiengesellschaft | Sensor assembly and method for determining the mechanical surface stresses and/or the microstructure state |
| US9909938B2 (en) | 2013-09-03 | 2018-03-06 | Siemens Aktiengesellschaft | Sensor arrangement and method for determining the mechanical surface stresses and/or the microstructure state |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0801102D0 (en) | 2008-02-27 |
| GB2456583B (en) | 2012-09-05 |
| WO2009093070A1 (en) | 2009-07-30 |
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