NON-DESTRUCTIVE TESTING USING PHASED ARRAYS

Abstract

A method of non-destructive testing of an article (20) is described. The article has a first surface (21). The article (20) article (20 comprises a set of passageways (200), including a first passageway (200 A). Respective sets of flaws (2000) are associated with respective passageways of the set of passageways (200), including a first set of flaws (2000A), optionally including a first flaw (2000AA), associated with the first passageway (200 A). The method comprises phased array ultrasonic scanning of the article (20) using a phased array probe communicatively coupled thereto through the first surface (21); and detecting the first flaw (2000AA), if included in the first set of flaws (2000A) associated with the first passageway (200A).

Claims

1: A method of non-destructive testing of an article having a first surface, wherein the article comprises a set of passageways, including a first passageway, and wherein respective sets of flaws are associated with respective passageways of the set of passageways, including at least a first flaw, associated with the first passageway, wherein the method comprises: phased array ultrasonic scanning of the article using a phased array probe communicatively coupled thereto through the first surface; and detecting the first flaw, wherein the phased array ultrasonic scanning of the first surface using the phased array probe comprises translating the phased array probe in a first direction, across the first surface, and wherein a longitudinal axis of the first passageway is transverse to the first surface, and intersects with the first surface.

2: The method according to claim 1, wherein the phased array ultrasonic scanning of the first surface using the phased array probe comprises translating the phased array probe in a set of directions, including the first direction, wherein the set of directions includes a second direction orthogonal to the first direction.

3: The method according to claim 2, wherein the set of directions includes a third direction that is angularly displaced from the first direction.

4: The method according to claim 1, wherein a longitudinal axis of the first passageway is orthogonal to the first surface.

5: The method according to claim 1 wherein the passageway defines a circular rim at the surface and the first direction in which the phased array probe is translated is parallel with a tangent to the rim.

6: The method according to claim 5 wherein over the course of a translation, the probe moves from a first position illuminating one side of the passageway, to a second position illuminating the other side.

7: The method according to claim 1, wherein the set of passageways is arranged as an array.

8: The method according to claim 1, wherein a cross-sectional dimension D, preferably a diameter, of the first passageway is in a range from 1 mm to 100 mm, preferably in a range from 5 mm to 50 mm, more preferably in a range from 8 mm to 20 mm.

9: The method according to claim 8, wherein a spacing between the first passageway and an adjacent passageway of the set of passageways is in a range from 0.5D to 10D, preferably 1 D to 7D, more preferably 2D to 5D.

10: The method according to claim 1, wherein the first passageway comprises a cylindrical passageway or a frustoconical passageway.

11: The method according to claim 1, wherein the first passageway is arranged to receive a mechanical fastener and optionally, wherein the article comprises the mechanical fastener received therein.

12: The method according to claim 1, wherein the article has a second surface, opposed to the first surface, and wherein the phased array ultrasonic scanning of the article using the phased array probe communicatively coupled thereto is only through the first surface.

13: The method according to claim 1, wherein the first flaw has a maximum dimension d in a range from 0.5 mm to 7 mm, preferably in a range from 1 mm to 5 mm.

14: The method according to claim 1, wherein the article has a thickness, measured normal to the first surface, in a range from 1 mm to 200 mm, preferably in a range from 5 mm to 100 mm, more preferably in a range from 10 mm to 50 mm.

15: The method according to claim 1, comprising stressing the article during the phased array ultrasonic scanning thereof.

16: The method according to claim 1, wherein the article is a component, preferably an aerospace component, included in an assembly, preferably an aircraft, and wherein the phased array ultrasonic scanning of the article comprises in situ phased array ultrasonic scanning of the article included in the assembly.

17: A method of non-destructive testing of an aerospace component, the method comprising applying phased array ultrasonic scanning to the aerospace component.

18: The method of claim 17, wherein the phased array ultrasonic scanning is in situ phased array ultrasonic scanning.

19: The method of claim 2, wherein the third direction is angularly displaced from the first direction by an angle of π/4.

20: The method of claim 2, wherein the set of directions further comprises a fourth direction that is orthogonal to the third direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0099] For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which:

[0100] FIG. 1 schematically depicts a method of non-destructive testing of an article according to an exemplary embodiment;

[0101] FIG. 2 shows a photograph of a method of non-destructive testing of an article according to an exemplary embodiment;

[0102] FIG. 3 shows a photograph of the method, in more detail;

[0103] FIG. 4A schematically depicts a cross-sectional view of a conventional fastener in an article, in use; FIG. 4B schematically depicts a cross-sectional view of a taperlock fastener, in use;

[0104] and FIG. 4C schematically depicts a cross-sectional view of the first passageway in the article of FIG. 2 for a countersunk taperlock fastener;

[0105] FIG. 5 schematically depicts a phased array ultrasonic scanning signal response from a base of the first passageway in the article of FIG. 2, tested according to an exemplary embodiment;

[0106] FIG. 6 schematically depicts a phased array ultrasonic scanning signal response from a first flaw associated with the first passageway of FIG. 5;

[0107] FIG. 7 schematically depicts a plan view of the article of FIG. 2, comprising a first passageway, tested according to an exemplary embodiment, in more detail;

[0108] FIG. 8 schematically depicts a phased array ultrasonic scanning signal response from a second flaw associated with a second passageway in the article of FIG. 2, tested according to an exemplary embodiment;

[0109] FIG. 9 schematically depicts a phased array ultrasonic scanning signal response from the second flaw of FIG. 8, in more detail;

[0110] FIG. 10 schematically depicts an aircraft;

[0111] FIG. 11 schematically depicts an aerospace component of the aircraft of FIG. 10, in situ;

[0112] FIG. 12A schematically depicts a plan view of an upper surface of the aerospace component of FIG. 11; and FIG. 12B schematically depicts a plan view of a lower surface of the aerospace component of FIG. 11.

DETAILED DESCRIPTION OF THE DRAWINGS

[0113] FIG. 1 schematically depicts a method of non-destructive testing of an article according to an exemplary embodiment.

[0114] The article, having a first surface, comprises a set of passageways, including a first passageway. Respective sets of flaws are associated with respective passageways of the set of passageways, including a first set of flaws. The first set of flaws optionally includes a first flaw, associated with the first passageway.

[0115] At S101, the article is phased array ultrasonic scanned using a phased array probe communicatively coupled thereto through the first surface.

[0116] At S102, the first flaw, if included in the first set of flaws associated with the first passageway, is detected.

[0117] FIG. 2 shows a photograph of a method of non-destructive testing of an article 10 according to an exemplary embodiment and FIG. 3 shows a photograph of the method, in more detail.

[0118] The article 10, having a first surface 11, comprises a set of passageways 100, including a first passageway 100A. Respective sets of flaws 1000 (not shown) are associated with respective passageways of the set of passageways 100, including a first set of flaws 1000A (not shown). The first set of flaws 1000A optionally includes a first flaw 1000AA, associated with the first passageway 100A.

[0119] In this example, the article 10 is a reference article, comprising a replica (i.e. a copy) of at least a part of an article, particularly a wing diffusion joint 20, as described below in more detail. The reference article is formed from L97 2024 in a T351 condition, particularly plate thereof having a thickness of 20 mm. The reference article 10 has the first reference surface 11, wherein the reference article 10 comprises the set of reference passageways 100, including the first reference passageway 100A, and wherein respective sets of reference flaws 1000 are associated with respective reference passageways of the set of reference passageways 1000, including a first set of reference flaws 1000A, including a first reference flaw 1000AA, associated with the first reference passageway 100A. That is, the reference article 10 includes deliberately introduced flaws, for example by machining such as electrical discharge machining (EDM). In this example, the first reference flaw 1000AA has a predetermined size, shape, orientation, location and/or property. In this way, calibrating the instrument, based on the first set of reference flaws 1000A, may be improved, thereby increasing probability of detection of the first flaw 1000AA and/or enhancing characterisation thereof. In this example, the article is otherwise as described with respect to the reference article 10.

[0120] In this example, a longitudinal axis of the first passageway 100A is orthogonal to the first surface 11 and the first passageway 100A intersects with the first surface 11. In this example, the first passageway 100A is a through hole (i.e. extending completely through the article 10, from the first surface 11 to an opposed, second surface, for example).

[0121] In this example, the set of passageways 100 is arranged as an irregular array. That is, the set of passageways 100 are not regularly arranged such that a spacing between adjacent passageways of the set of passageways 100 varies.

[0122] In this example, a diameter D of the first passageway 100A is in a range from 11 mm to 14 mm. In this example, a cross-sectional shape of the first passageway 100A is circular.

[0123] In this example, a spacing between the first passageway 100A and an adjacent passageway of the set of passageways 100 is in a range from 2D to 5D. In this example, a centre spacing between a centre of the first passageway 100A and a centre of an adjacent passageway of the set of passageways 100 is in a range from 3D to 6D. That is, the passageways 100 are relatively closely spaced, such that physical access to first passageway 100A, is restricted.

[0124] In this example, the first passageway 100A comprises a frustoconical passageway (i.e. a tapered passageway) arranged to receive a countersunk taperlock fastener 50A therein and optionally, the article 10 comprises the taperlock fastener 50A received therein.

[0125] In this example, the set of passageways 100 includes N passageways 100A to 100T, where N is 20. The passageways 100A to 100P are shown and the passageways 100Q to 100T are not shown (obscured). In this example, the passageways 100A to 100D comprise countersunk taperlock fasteners 50A to 50D, respectively, received therein. In this example, each passageway of the set of passageways 100 is generally otherwise as described with respect to the first passageway 100A.

[0126] Particularly, the method is performed using an Olympus Ominscan SX (reference sign I), a compatible phased array probe (reference sign P) and a corresponding wedge (reference sign W) for the phased array probe.

[0127] Prior to carrying out NDT of an article, as described below, the reference article 10 including simulated cracks (EDM notches) from bores is used to check the set-up sensitivity of the instrument I and act as a good to go check.

[0128] Generally, the first surface 11 is cleaned, degreased and ensured free from corrosion. Preferably, the first surface 11 is as smooth as possible to prevent acoustic signal deformation and reduce resultant measurement error. The geometry of the scan surface 11 should be as parallel as possible to the surface of the probe shoe, to enable an optimal acoustic reflection. This will prevent difficulties in obtaining a return signal from the reflector surface. Any sharp dents, gouges, nicks, scratches or machine marking must be dressed as far as practicable to allow the ultrasonic inspection to be conducted on an acceptable surface.

[0129] A coupling medium, for example Sound Clear Soundclear® 60, available from Magnaflux, or any other couplant approved by the UT Level 3, is applied to the first surface 11. Response is optimised for the first flaw 1000AA. The coupling medium is removed from the first surface following NDT.

[0130] FIG. 4A schematically depicts a cross-sectional view of a conventional fastener B in an article 10, in use; FIG. 4B schematically depicts a cross-sectional view of a taperlock fastener 50 in an article 10, in use; and FIG. 4C schematically depicts a cross-sectional view of a first passageway 100A in an article 10 for a countersunk taperlock fastener 50A.

[0131] The conventional fastener B, for example a bolt, exerts forces on the opposed first surface 11 and second surface 12 of the article 10, with stresses raised therein proximal the opposed surfaces 11, 12 around the cylindrical walls of the fastener hole H.

[0132] In contrast, as described above, the taperlock fastener 50 exerts a force on the tapered walls of the fastener hole (i.e. the first passageway 100A) because of its tapered shape. The taperlock fastener 50 is designed to completely fill the first passageway 100A, but unlike a rivet or the bolt B for example, the tapered shank fills the tapered first passageway 100A without deforming the shank. Instead, the washer head nut compresses the shank against the tapered walls of the first passageway 100A. This creates radial compression in the article 10 around the shank and axial compression in the article 10 as the taperlock fastener 50 is fastened. However, while stresses are not raised as with conventional mechanical fasteners, fatigue, corrosion and/or stress-corrosion cracking may be problematic following extended operation and/or adverse operating conditions. Hence, NDT of such articles is required.

[0133] FIG. 5 schematically depicts a phased array ultrasonic scanning signal response from a base of the first passageway 100A in the article 10, tested according to an exemplary embodiment.

[0134] Particularly, FIG. 5 shows: (A) an A-scan; (B) an S-scan of the response due to the base of the first passageway 100A in the article 10.

[0135] FIG. 6 schematically depicts a phased array ultrasonic scanning signal response from a first flaw 1000AA associated with the first passageway 100A of FIG. 5.

[0136] Particularly, FIG. 6 shows: (A) an A-scan; (B) an S-scan of the response due to the first flaw 1000AA associated with the first passageway 100A. The first flaw 1000AA is a notch, having dimensions 3 mm×3 mm, deliberately introduced by EDM.

[0137] FIG. 7 schematically depicts a plan view of the article 10, comprising the first passageway 100A and its associated circular rim, tested according to an exemplary embodiment, in more detail. The phased array probe P is shown in 4 positions, 1 to 4, wherein the 4 positions are mutually angularly spaced apart and equispaced from the passageway 100A.

[0138] The phased array probe P is translated in respective directions parallel to respective tangents to the passageway 100A (i.e. tangents to the circular rim). Over the course of a translation the probe moves from a first position illuminating one side of the passageway 100A to a second position illuminating the other side, thereby sequentially scanning the entire passageway 100A.

[0139] In this example, the phased array ultrasonic scanning of the first surface 11 using the phased array probe P comprises translating the phased array probe P in a set of directions, including a first direction Y, as shown at position 1, across the first surface 11. The set of directions includes a second direction X, as shown at position 2, orthogonal to the first direction Y.

[0140] In this example, the set of directions includes a third direction Y′ angularly displaced from the first direction Y, as shown at position 3, by Tr/4 radians, and, a fourth direction X′, as shown at position 4, orthogonal to the third direction Y′.

[0141] Each of directions X, Y, X′ and Y′ is equispaced from the passageway 100A (i.e. the line extending orthogonally from the direction to the centre of the passageway 100A is the same length).

[0142] The spacing of the directions from the passageway is selected with regard to the radiation pattern of the probe. Particularly, the spacing is selected such that the beam from the phased array ultrasonic scanner tends to spread onto a sufficient range of depths of the passageway.

[0143] FIG. 8 schematically depicts a phased array ultrasonic scanning signal response from a first flaw 1000BA associated with a second passageway 100B in the article 10, tested according to an exemplary embodiment.

[0144] Particularly, FIG. 8 shows an S-scan of the response due to the first flaw 1000BA associated with the second passageway 100B.

[0145] FIG. 9 schematically depicts a phased array ultrasonic scanning signal response from the first flaw 1000BA associated with the second passageway 100B in the article 10, tested according to an exemplary embodiment.

[0146] Particularly, FIG. 9 shows an S-scan of the response due to the first flaw 1000BA associated with the second passageway 100B, in more detail.

[0147] FIG. 10 schematically depicts an aircraft A. In this example, the aircraft is a military aircraft, particularly a swept wing aircraft, specifically a Tornado. Regions of interest for NDT are indicated by dashed circles.

[0148] FIG. 11 schematically depicts an aerospace component 20 of the aircraft A of FIG. 10, in situ. Particularly, the aerospace component 20 is a wing diffusion joint, formed from L97 2024 in a T351 condition, particularly plate thereof. In this example, the article 20 is generally as described with respect to the reference article 10, description of which is not repeated, for brevity.

[0149] The article 20, having a first surface 21, comprises a set of passageways 200, including a first passageway 200A. Respective sets of flaws 2000 (not shown) are associated with respective passageways of the set of passageways 200, including a first set of flaws 2000A (not shown). The first set of flaws 2000A optionally includes a first flaw 2000AA, associated with the first passageway 200A.

[0150] In this example, the set of passageways 200 includes N passageways, where N is 81, comprising countersunk taperlock fasteners 50, respectively received therein. In this example, each passageway of the set of passageways 200 is generally otherwise as described with respect to the first passageway 200A. NDT is performed for the 81 passageways, as described above.

[0151] FIG. 12A schematically depicts a plan view of an upper surface (i.e. the first surface 21) of the aerospace component 20 of FIG. 11; and FIG. 12B schematically depicts a plan view of a lower surface (i.e. a second surface 22) of the aerospace component 20 of FIG. 11. The aerospace component 20 is disassembled from the aircraft A, for visual inspection of the lower surface 22.

[0152] Particularly, corrosion at or proximal the lower surface 22 may increase occurrence of flaws associated with the first set of passageways 200, for example, due to stress corrosion cracking. Hence, in situ NDT, as described herein, increases longevity of these aircraft and/or allows operational use thereof beyond original design limits without disassembly.

[0153] Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

[0154] In summary, the invention provides a method of non-destructive testing and use of phased array ultrasonic scanning. In this way, NDT of the article is facilitated, enabling NDT thereof even if physical access to the article, particularly the first passageway, is restricted. In this way, if the article is a component in an assembly, for example an aerospace component mechanically fastened in an aircraft, NDT of the article in situ (i.e. in the original place, as assembled) is facilitated such that disassembly of the assembly may not be required in order to perform NDT of the article, thereby decreasing complexity, duration and/or cost of the NDT. Furthermore, if disassembly is not required, new mechanical fasteners to replace removed mechanical fasteners are also not required.

[0155] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0156] All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at most some of such features and/or steps are mutually exclusive.

[0157] Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0158] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.