Phased array ultrasonic probe in star-shaped surrounding arrangement

Abstract

The invention discloses a phased array ultrasonic probe arranged in a star-shaped surrounding mode, and belongs to the technical field of nondestructive testing. The method is especially suitable for non-destructive detection of internal structure defects of high-attenuation materials such as epoxy composite materials. In order to solve the problems of a traditional phased array ultrasonic probe in detection of internal defects of an epoxy composite insulating material, the invention provides a phased array ultrasonic probe in star-shaped surrounding arrangement, sound field focusing is optimized through star-shaped surrounding arrangement, and focusing of deep energy is improved; the circular wafer is designed, large-angle deflection of the acoustic beam is achieved, the device is suitable for comprehensive detection of complex structural parts, meanwhile, the near-field blind area is small, and the omission ratio of defects in the near-field area is reduced; a large-size wafer can bear higher voltage, so that high-energy ultrasonic waves are emitted, and large-depth and high-precision defect detection inside a workpiece is realized; a small-size wafer is used for receiving signals with high sensitivity and cooperatively dividing labor with a large-size wafer, so that the detection capability of an existing ultrasonic phased array is broken through.

Description

Technical Field

[0001] The present invention belongs to the technical field of nondestructive testing, and particularly relates to a phased array ultrasonic probe based on a star-shaped surrounding arrangement of array elements and a detection method thereof, which is particularly suitable for non-destructive detection of internal structural defects of high-attenuation materials such as epoxy composite materials. Background Art

[0002] Due to its excellent electrical insulation performance, epoxy composite materials have been widely used in equipment in the power industry. In particular, large structural pot insulators are mainly made of epoxy resin casting. During the vacuum mixing and casting processes, the treatment effect of the mixture is poor, which will increase the occurrence probability of defects such as air bubbles and impurities; the sharp corners and burrs on the surface of the mold cavity and inserts will cause stress concentration on the insulating parts. Especially during the handling and installation processes, cracks are likely to occur at the stress concentration points. The existence of these defects poses a risk of insulation breakdown of the equipment, thereby triggering equipment failures and causing huge losses. Therefore, it is of great significance to detect the defects existing inside the epoxy composite material of the pot insulator early to ensure the safe operation of the power system.

[0003] At present, nondestructive testing technologies including X-ray detection lack reliable detection capabilities for internal defects, internal air bubbles, and interface defects in epoxy composite materials, resulting in the operation of epoxy resin insulating parts with undetected diseases, which has currently become the main cause of insulating equipment failures. Ultrasonic testing technology has received more attention in the detection of internal defects of epoxy resin insulating parts due to its advantages of low cost, portability, and high reliability. However, ordinary epoxy resin insulating parts are usually prepared by mixing epoxy resin and micron-sized Al2O3 ceramic particles, which themselves have high sound attenuation characteristics. In addition, general industrial inspections have a high missed detection rate for internal defects in large-sized and complex-structured workpieces. Using ultrasonic phased array detection technology can focus the acoustic wave energy and deflect the acoustic beam at a large angle to detect deep internal defects in complex-structured parts. However, due to the limitations of the probe wafer size and arrangement method, the power of the phased array probe is low and high-precision detection of deep internal defects in epoxy resin insulating parts cannot be achieved. Summary of the Invention

[0004] Aiming at the problems existing in the detection of internal defects of epoxy composite insulation materials by traditional phased array ultrasonic probes, the present invention proposes a phased array ultrasonic probe with a star-shaped surrounding arrangement, which optimizes the sound field focusing through the star-shaped surrounding arrangement to improve the focusing of deep energy; designs circular wafers to achieve large-angle deflection of the acoustic beam, which is suitable for comprehensive detection of complex-structured parts, and at the same time has a small near-field blind area, reducing the missed detection rate of near-field area defects; uses large-sized wafers that can carry higher voltages to emit high-energy ultrasonic waves, thereby realizing large-depth and high-precision defect detection inside workpieces; uses small-sized wafers to receive signals with high sensitivity and cooperate with large-sized wafers to break through the detection capabilities of existing ultrasonic phased arrays.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A phased array ultrasonic probe with a star-shaped surrounding arrangement, the phased array ultrasonic probe comprising a housing, a sleeve, a backing, a first metal coating, a second metal coating, sixteen small array elements, one large array element and a matching layer;

[0007] The housing is a hollow shell with a wire outlet hole provided at the top end face; the bottom is replaced by a matching layer of the same shape; the outer side wall of the sleeve is closely attached to the inner side wall of the housing, and the inner side wall of the sleeve is closely attached to the backing; the top inner wall of the housing is closely attached to the backing;

[0008] Sixteen small array elements are arranged evenly around the large array element, and both the small array elements and the large array element are arranged between the first metal coating and the second metal coating; the outer end face of the first metal coating is attached to the backing; the outer end face of the second metal coating is attached to the matching layer.

[0009] Furthermore, the material of the backing is composed of a composite material of tungsten powder / epoxy resin + nano silicon carbide, and the attenuation coefficient should be greater than 35 dB / cm / MHz. After polishing treatment, it is closely attached to the first metal coating. It has high acoustic attenuation to absorb the sound waves emitted by the wafer towards the back, thereby reducing the interference of clutter.

[0010] Furthermore, the material of the matching layer is an alumina powder / epoxy resin material with a mass ratio of 1:3, the acoustic impedance is 15 MRayl, and the thickness is one-fourth of the wavelength, which is 1.4 mm. It can enable good transmission of acoustic energy, thereby improving the detection sensitivity.

[0011] Furthermore, the small array element is a piezoelectric wafer, and the material of the piezoelectric wafer is a composite material of PZT doped with 0.5 mol% neodymium oxide (Nd2O3); the piezoelectric coefficient d33 is 400 pC / N, which has high receiving sensitivity. There are 16 small array elements in total, and the resonance frequency is 0.5 MHz.

[0012] Furthermore, the large array element is a piezoelectric wafer, and the material of the piezoelectric wafer is a lead magnesium niobate-lead titanate (PMN-PT) composite material; the volume of PMN accounts for 70% of the volume of the composite material, the piezoelectric strain coefficient d33 is 700 pC / N, which has the ability to emit high-energy ultrasonic waves. There is 1 large array element in total, the resonance frequency is 0.5 MHz, and the cross-sectional area is four times that of the small array element.

[0013] Furthermore, the second metal coating is bonded to sixteen small array elements and one large array element. The large array element is used to transmit ultrasonic waves, and the small array elements are used to receive ultrasonic waves. The large array element improves the energy density of the transmission voltage and the transmitted sound beam due to its size and shape, thereby improving the detection depth and accuracy. The total occupied area is reduced by 15% compared with the conventional phased array elements, meeting the requirement of probe miniaturization; at the same time, a 360° uniform signal response can be achieved, improving the sound field coverage of complex structural parts.

[0014] Furthermore, the phased array ultrasonic probe further includes a cable. The cable passes through the wire outlet hole and the backing and is electrically connected to the first metal coating. The cable is welded to the first metal coating for transmitting and receiving electrical signals.

[0015] Furthermore, the phased array ultrasonic probe further includes a circumferential scanning area wedge. The circumferential scanning area wedge and the housing are connected by bolts. The end face of the circumferential scanning area wedge is in contact with the inspected pot insulator, and the end face of the circumferential scanning area wedge in contact with the inspected pot insulator is an arc surface, and the curvature of the arc surface is consistent with the curvature of the circumferential area of the pot insulator. Further, the material of the circumferential scanning area wedge is polyimide.

[0016] A phased array ultrasonic probe designed by the present invention with a star-shaped surrounding arrangement realizes high-precision detection of internal defects of large-sized insulators through scanning and detecting the circumferential area of the epoxy composite material of the in-service pot insulator.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] In the star-shaped surrounding arrangement of the phased array ultrasonic probe described in the present invention, in the star-shaped arrangement, the circular large array element can withstand a higher excitation voltage and thus excite high-energy sound waves, improving the propagation distance of the sound waves in the inspected workpiece and the accuracy of defect detection; the ultrasonic energy emitted by the circular large array element wafer is more concentrated, and has a better signal-to-noise ratio for defect detection in the far field area, and the detection reliability is higher; the near-field detection blind area of the circular array elements arranged in a star shape is smaller, and can accurately capture the fine defects at the bonding interface between the epoxy composite material and the metal insert; when the circular small array elements receive signals, a 360° uniform response can be achieved, avoiding signal interference caused by the sound beam diffusion in the long side direction of the rectangular array elements. The circular array elements support large-angle sound beam deflection to achieve full circumferential sound field coverage of the umbrella skirt curved surface of the pot insulator; small circular array elements are surrounded around the large array element, and the total occupied area is reduced by about 15% compared with the conventional rectangular array, meeting the requirement of probe miniaturization. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0020] Figure 1 Schematic diagram of the phased array ultrasonic probe structure arranged in a star-shaped surround in the embodiments of the present invention;

[0021] Figure 2 Schematic diagram of the wafer arrangement of the phased array ultrasonic probe in the embodiments of the present invention;

[0022] Figure 3 Energy field distribution diagram of a circular wafer ultrasonic probe;

[0023] Figure 4 Energy field distribution diagram of a rectangular wafer ultrasonic probe;

[0024] Figure 5 Near-field range diagram of a circular wafer ultrasonic probe;

[0025] Figure 6 Near-field range diagram of a rectangular wafer ultrasonic probe;

[0026] Figure 7 Schematic diagram of defect detection by the phased array ultrasonic probe arranged in a star-shaped surround in the embodiments of the present invention;

[0027] Figure 8 Schematic diagram when the phased array ultrasonic probe arranged in a star-shaped surround in the embodiments of the present invention detects a pot-type insulator;

[0028] Figure 9 Front view of the wedge block in the circumferential scanning area of the pot-type insulator in the embodiments of the present invention;

[0029] Figure 10 Longitudinal sound pressure comparison distribution diagram between the star-shaped surround probe and the conventional array probe of the present invention;

[0030] Figure 11 Two-dimensional sound intensity distribution simulation diagram of the phased array ultrasonic probe arranged in a star-shaped surround of the present invention;

[0031] Figure 12 A-scan result simulation diagram of the detection of internal defects in epoxy insulation materials by a conventional linear array phased array ultrasonic probe and the designed star-shaped surround phased array ultrasonic probe of the present invention.

[0032] Reference signs: 1, housing; 2, sleeve; 3, backing; 4, first metal coating; 5, second metal coating; 6, small array element; 7, large array element; 8, matching layer; 9, bolt; 10, wire outlet hole; 11, cable; 12, detection probe; 13, circumferential scanning area wedge block. Detailed implementation manners

[0033] In order to deeply understand the present invention, a comprehensive and detailed description will be given. However, the present invention has various implementation manners and is not limited to the specific examples listed herein. The presentation of these examples aims to deepen the comprehensive understanding of the disclosed content of the present invention.

[0034] Referring to Figure 1 As shown, the phased array ultrasonic probe with star-shaped surrounding arrangement of the present invention includes a housing 1, a sleeve 2, a backing 3, a first metal coating 4, a second metal coating 5, sixteen small array elements 6, a large array element 7 and a matching layer 8;

[0035] The housing 1 is a hollow shell, and a wire outlet hole 10 is provided at the top end face; the bottom is replaced by a matching layer (8) of the same shape; the outer side wall of the sleeve 2 is closely attached to the inner side wall of the housing 1, and the inner side wall of the sleeve 2 is closely attached to the backing 3; the top inner wall of the housing 1 is closely attached to the backing 3;

[0036] As Figure 2 shown is a schematic diagram of the wafer arrangement of the phased array ultrasonic probe of the present invention. Sixteen small array elements 6 are arranged evenly around the large array element 7, and both the small array elements 6 and the large array element 7 are arranged between the first metal coating 4 and the second metal coating 5; the outer end face of the first metal coating 4 is attached to the backing 3; the outer end face of the second metal coating 5 is attached to the matching layer 8.

[0037] Furthermore, the material of the backing 3 is composed of a composite material of tungsten powder / epoxy resin + nano silicon carbide, and the attenuation coefficient should be greater than 35 dB / cm / MHz. It is closely attached to the first metal coating 4 after polishing treatment.

[0038] Furthermore, the material of the matching layer 8 is an alumina powder / epoxy resin material with a mass ratio of 1:3, the acoustic impedance is 15 MRayl, and the thickness is one-fourth of the wavelength, which is 1.4 mm.

[0039] Furthermore, the small array element 6 is a piezoelectric wafer, and the material of the piezoelectric wafer is a composite material of PZT doped with 0.5 mol% neodymium oxide (Nd2O3); the piezoelectric coefficient d33 is 400 pC / N, having high receiving sensitivity, and there are 16 small array elements in total, and the resonance frequency is 0.5 MHz.

[0040] Furthermore, the large array element 7 is a piezoelectric wafer, and the material of the piezoelectric wafer is a lead magnesium niobate-lead titanate (PMN-PT) composite material; the volume of PMN accounts for 70% of the volume of the composite material, the piezoelectric strain coefficient d33 is 700 pC / N, and it has the ability to emit high-energy ultrasonic waves. There is a total of 1 large array element, the resonant frequency is 0.5 MHz, and the cross-sectional area is four times that of the small array element.

[0041] Furthermore, the second metal coating 5 is bonded to the sixteen small array elements 6 and one large array element 7.

[0042] Refer to Figures 3 to 6 As shown, the detection probes all use circular array element wafers, which avoid the energy attenuation caused by the sound beam diffusion in the long side direction of the rectangular array elements, making the ultrasonic energy more concentrated and having a higher signal-to-noise ratio for defect detection in the far field area; at the same time, the near-field detection blind area of the circular array element wafer is smaller, which can greatly reduce the missed detection of defects at the joint interface between the near-field epoxy composite material and the metal insert.

[0043] Furthermore, the phased array ultrasonic probe further includes a cable 11. The cable 11 passes through the wire outlet hole 10 and the backing 3 and is electrically connected to the first metal coating 4. The cable 11 is welded to the first metal coating 4 for transmitting and receiving electrical signals.

[0044] As Figure 7 shown, it is the working schematic diagram of the detection probe; refer to Figure 8 As shown, the phased array ultrasonic probe 12 further includes a circumferential scanning area wedge 13. The circumferential scanning area wedge 13 and the housing 1 are connected by bolts 9. The end face of the circumferential scanning area wedge 13 is in contact with the inspected pot insulator, and the end face of the circumferential scanning area wedge 13 in contact with the inspected pot insulator is an arc surface, and the curvature of the arc surface is consistent with the curvature of the circumferential area of the pot insulator.

[0045] Furthermore, the material of the circumferential scanning area wedge 13 is polyimide. Polyimide is an organic polymer material with more prominent acoustic performance and thermal stability performance. Its dielectric constant is about 3.4, and the dielectric loss is very small, only 10 -3 . The loss of ultrasonic signals during transmission in the wedge can be ignored.

[0046] Test example

[0047] By comparing the longitudinal sound pressure distribution diagrams of the conventional linear array phased array ultrasonic probe and the star-shaped circumferential phased array ultrasonic probe of the present invention, as Figure 10 shown, it can be seen that the star-shaped circumferential phased array ultrasonic probe of the present invention has a higher sound pressure distribution, and at the same time, the near-field detection blind area is shortened by about 3 mm compared with the conventional array probe, reducing the missed detection rate of surface defects of the test piece.

[0048] Furthermore, by simulating the two-dimensional sound intensity distribution of a phased array ultrasonic probe with a star-shaped surrounding arrangement designed by the present invention, as Figure 11 shown, it can be seen that it has a good sound beam focusing effect, the sound beam energy is more concentrated, and the detection result of internal defects in epoxy insulation composite materials is more accurate.

[0049] By simulating the A-scan results of detecting internal defects in epoxy insulation materials with a conventional linear array phased array ultrasonic probe and the designed star-shaped surrounding phased array ultrasonic probe, as Figure 12 shown, it can be seen that due to the larger transmitting array elements, the designed star-shaped surrounding phased array ultrasonic probe has a higher initial wave energy, and at the same time, the defect signal response is also higher, having better defect detection sensitivity.

[0050] The content not described in detail in the specification of the present invention belongs to the prior art well-known to those skilled in the art. Although the above-described illustrative specific embodiments of the present invention are described to facilitate the understanding of the present invention by those skilled in the technical field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the technical field, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

Claims

1. A phased array ultrasonic probe with a star-shaped surrounding arrangement, characterized in that: The phased array ultrasonic probe includes a housing (1), a sleeve (2), a backing (3), a first metal coating (4), a second metal coating (5), sixteen small elements (6), a large element (7), and a matching layer (8); The housing (1) is a hollow shell with a wire outlet hole (10) provided at the top end face; the bottom is replaced by a matching layer (8) of the same shape; the outer side wall of the sleeve (2) is closely attached to the inner side wall of the housing (1), and the inner side wall of the sleeve (2) is closely attached to the backing (3); the top inner wall of the housing (1) is closely attached to the backing (3); Sixteen small elements (6) are arranged uniformly around the large element (7), and both the small elements (6) and the large element (7) are arranged between the first metal coating (4) and the second metal coating (5); the outer end face of the first metal coating (4) is attached to the backing (3); the outer end face of the second metal coating (5) is attached to the matching layer (8).

2. The phased array ultrasonic probe arranged in a star-shaped surrounding according to claim 1, wherein: The material of the backing (3) is composed of a composite material of tungsten powder / epoxy resin + nano silicon carbide, and the attenuation coefficient should be greater than 35 dB / cm / MHz.

3. The phased array ultrasonic probe arranged in a star-shaped surround according to claim 1, characterized in that: The material of the matching layer (8) is an alumina powder / epoxy resin material with a mass ratio of 1:3, the acoustic impedance is 15 MRayl, and the thickness is one quarter of the wavelength, which is 1.4 mm.

4. The phased array ultrasonic probe arranged in a star-shaped surrounding according to claim 1, characterized in that: The small element (6) is a piezoelectric wafer, and the material of the piezoelectric wafer is a composite material of PZT doped with 0.5 mol% neodymium oxide; The piezoelectric coefficient d33 is 400 pC / N, with high receiving sensitivity, and there are 16 small elements in total, and the resonant frequency is 0.5 MHz.

5. The phased array ultrasonic probe arranged in a star-shaped surrounding according to claim 1, characterized in that: The large element (7) is a piezoelectric wafer, and the material of the piezoelectric wafer is a lead magnesium niobate-lead titanate composite material; the volume of PMN accounts for 70% of the volume of the composite material, the piezoelectric strain coefficient d33 is 700 pC / N, with the ability to emit high-energy ultrasonic waves, and there is 1 large element in total, the resonant frequency is 0.5 MHz, and the cross-sectional area is four times that of the small element.

6. A phased array ultrasonic probe arranged in a star-shaped surrounding manner according to claim 1, characterized in that: The second metal coating (5) is bonded to sixteen small elements (6) and a large element (7).

7. The phased array ultrasonic probe arranged in a star-shaped surrounding according to claim 1, characterized in that: The phased array ultrasonic probe further includes a cable (11), the cable (11) passes through the wire outlet hole (10) and the backing (3) and is electrically connected to the first metal coating (4), and the cable (11) is welded to the first metal coating (4) for transmitting and receiving electrical signals.

8. The phased array ultrasonic probe arranged in a star-shaped surrounding manner according to claim 1, wherein: The phased array ultrasonic probe further includes a circumferential scanning area wedge block (13), the circumferential scanning area wedge block (13) and the housing (1) are connected by bolts (9), the end face of the circumferential scanning area wedge block (13) is in contact with the inspected pot-type insulator, and the end face of the circumferential scanning area wedge block (13) in contact with the inspected pot-type insulator is an arc surface, and the curvature of the arc surface is consistent with the curvature of the circumferential area of the pot-type insulator.

9. The phased array ultrasonic probe arranged in a star-shaped surrounding according to claim 1, characterized in that: The material of the circumferential scanning area wedge block (13) is polyimide.

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