CN113777156B - double-D focusing coil array far-field eddy current probe and detection method thereof - Google Patents
double-D focusing coil array far-field eddy current probe and detection method thereof Download PDFInfo
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- CN113777156B CN113777156B CN202111090288.2A CN202111090288A CN113777156B CN 113777156 B CN113777156 B CN 113777156B CN 202111090288 A CN202111090288 A CN 202111090288A CN 113777156 B CN113777156 B CN 113777156B
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- 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
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- G—PHYSICS
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- 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
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Abstract
A double-D focusing coil array far-field eddy current probe and a detection method thereof. The double-D focusing coil array far-field eddy current probe comprises an excitation unit for generating a focusing excitation magnetic field, a detection unit for picking up detection signals and a shielding unit for shielding a direct coupling channel electromagnetic field, wherein the excitation unit comprises a double-D excitation coil inclined at a certain angle and a magnetic field structure. According to the double-D focusing coil array far-field eddy current probe, the magnetic field is focused to the riveting piece by arranging the double-D focusing coils, so that the low-frequency electromagnetic field generated by the coils can penetrate to a deeper depth, and deeper buried depth defects can be detected more conveniently; in addition, the array detection coils are arranged in a linear array, so that the defect length can be evaluated by using the array detection signals, and major accidents are avoided. In addition, the invention also provides a detection method applied to the double-D focusing coil array far-field eddy current probe.
Description
Technical Field
The invention relates to the technical field of aircraft riveting structural member detection, in particular to a double-D focusing coil array far-field eddy current probe and a detection method thereof.
Background
The riveted structure is a main connection mode for the assembly of the aircraft structure, and the aircraft body is affected by alternating stress in the flight process, so that stress concentration is generated around holes of the riveted part, fatigue cracks are initiated, and the aircraft body is broken to cause serious accidents. The existing eddy current detection technology has the advantages of no need of couplant, high detection speed, high sensitivity, in-service detection and the like, so that the eddy current detection technology is widely applied to aircraft riveting part detection, and particularly, a far-field eddy current probe with a detection coil and an excitation coil crossing the center of a rivet is generally adopted to enable the eddy current probe to rotationally detect hole periphery crack defects of a riveting structure, but the far-field eddy current detection probe can only effectively detect crack defects with shallow burial depth and can not detect hidden defects with deep burial depth, and the length of the cracks can not be effectively evaluated, so that the riveting part still has great potential safety hazards.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a double-D focusing array far-field eddy current testing probe and a testing method thereof, wherein the double-D focusing array far-field eddy current testing probe can effectively detect defects deeper than the prior art and evaluate the lengths of crack defects.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the utility model provides a two D focusing coil array far field eddy current probe, includes the excitation unit that is used for producing focus excitation magnetic field, the detecting element that is used for picking up the detected signal and is used for shielding the shielding unit of direct coupling passageway electromagnetic field, the excitation unit is including the two D excitation coils and the magnetic field structure that incline at certain angle, the detecting element includes array detection coil group and array magnetic circuit structure, the shielding unit includes first shield, second shield and third shield, the shielding unit is multilayer shielding structure.
Further, the double-D excitation coil is two D-shaped winding coils, the double-D excitation coil is symmetrically placed along the axes of the excitation unit and the detection unit at a certain angle and wound in the same direction, the magnetic field structure is D-shaped, and the double-D excitation coil is wound in the magnetic field structure.
Further, the array detection coil set is a rectangular linear array coil set, the array magnetic circuit structure is a cuboid, and the array detection coil set is wound in the array magnetic circuit structure.
Further, the first shielding piece is coated on the double-D excitation coil and the magnetic field structure, the first shielding piece and the excitation unit are both fixedly arranged on the third shielding piece, the second shielding piece is coated on the array detection coil set and the array magnetic circuit structure, and the second shielding piece and the detection unit are both fixedly arranged on the third shielding piece.
Further, the first shielding piece and the second shielding piece are made of aluminum alloy materials, the third shielding piece is made of copper materials, and the magnetic field structure and the array magnetic circuit structure are made of ferrite or silicon steel materials.
Furthermore, the double-D excitation coil is simultaneously electrified with sinusoidal excitation signals with the same phase and the same frequency, and the turns of the double-D excitation coil are consistent.
Further, the excitation unit and the detection unit are placed across the rivet.
A dual D focusing coil array eddy current testing method applied to the dual D focusing coil array far field eddy current probe as described above, the method comprising the steps of:
step one: the double-D focusing excitation coil arranged on the detected riveting structural member is communicated with a low-frequency sine wave signal with the same frequency, and the double-D focusing excitation coil is arranged in the detected riveting structural member at a certain inclination angle to generate a focusing low-frequency magnetic field;
step two: the excitation unit and the detection unit are placed across the rivet, the double-D focusing array far-field eddy current detection probe is rotated along the surface of the rivet, so that the array detection coil which is arranged at the hole edge and is in a linear array picks up eddy current field signals containing internal defect information of the rivet to be detected in a far field region, and the signals are sent to the signal conditioning module and the display module.
The invention provides a double-D focusing coil array far-field eddy current probe, which comprises an excitation unit for generating a focusing excitation magnetic field, a detection unit for picking up detection signals and a shielding unit for shielding a direct coupling channel electromagnetic field, wherein the excitation unit comprises a double-D excitation coil inclined at a certain angle and a magnetic field structure, the detection unit comprises an array detection coil group and an array magnetic circuit structure, and the shielding unit is of a multilayer shielding structure. According to the double-D focusing coil array far-field eddy current probe, the double-D focusing coils are arranged to focus a magnetic field to the riveting piece, so that a low-frequency electromagnetic field generated by the coils can penetrate to a deeper depth, and deeper buried depth defects can be detected more easily; in addition, the array detection coils are arranged in a linear array, so that the defect length can be evaluated by using the array detection signals, and major accidents are avoided.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the drawings that need to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort to those skilled in the art.
FIG. 1 is an exploded view of a dual D focusing coil array far field eddy current probe of the present invention;
FIG. 2 is a schematic diagram of placement of a dual D focusing coil array far field eddy current probe of the present invention;
fig. 3 is a schematic diagram of a method for detecting far-field eddy currents with a dual-D focusing coil array according to the present invention.
The names corresponding to the reference numerals in the drawings are:
the dual-D excitation coil 1, a magnetic field structure 2, a first shielding piece 3, an array detection coil set 4, an array magnetic circuit structure 5, a second shielding piece 6, a third shielding piece 7, a signal conditioning module 8 and a display module 9.
Detailed Description
The following are preferred embodiments of the present invention, and it should be noted that modifications and variations can be made by those skilled in the art without departing from the principle of the present invention, and these modifications and variations are also considered as the protection scope of the present invention.
Referring to fig. 1-3, a dual D focusing coil array far-field eddy current probe of the present invention includes an excitation unit for generating a focusing excitation magnetic field, a detection unit for picking up a detection signal, and a shielding unit for shielding a direct coupling channel electromagnetic field, the excitation unit includes a dual D excitation coil 1 inclined at an angle and a magnetic field structure 2, the detection unit includes an array detection coil set 4 and an array magnetic circuit structure 5, the shielding unit includes a first shielding member 3, a second shielding member 6, and a third shielding member 7, and the shielding unit is a multi-layer shielding structure.
In one embodiment, the double-D excitation coil is two D-shaped winding coils, the double-D excitation coils are symmetrically placed along the axes of the excitation unit and the detection unit at a certain angle and are wound in the same direction, the magnetic field structure is D-shaped, and the double-D excitation coils are wound in the magnetic field structure.
In one embodiment, the array detection coil set is a rectangular linear array coil set, the array magnetic circuit structure is a cuboid, and the array detection coil set is wound in the array magnetic circuit structure.
In one embodiment, the first shielding member 3 is coated outside the dual-D excitation coil 1 and the magnetic field structure 2, the first shielding member 3 and the excitation unit are both fixedly arranged on the third shielding member 7, the second shielding member 6 is coated outside the array detection coil set 4 and the array magnetic circuit structure 5, and the second shielding member 6 and the detection unit are both fixedly arranged on the third shielding member 7.
In one embodiment, the first shielding member 3 and the second shielding member 6 are made of aluminum alloy material, the third shielding member 7 is made of copper material, and the magnetic field structure 2 and the array magnetic circuit structure 5 are made of ferrite or silicon steel material.
In one embodiment, the double-D excitation coil is simultaneously supplied with sinusoidal excitation signals with the same phase and frequency, and the turns of the double-D excitation coil are consistent.
In one embodiment, the excitation unit and the detection unit are placed across the rivet.
The invention also provides a double-D focusing coil array eddy current detection method, which comprises the following steps: the double-D focusing excitation coil arranged on the detected riveting structural member is communicated with a low-frequency sine wave signal with the same frequency, and the double-D coil is arranged in the detected riveting structural member at a certain inclination angle to generate a focusing low-frequency magnetic field; as shown in fig. 2, the excitation unit and the detection unit are placed across the rivet, and the double-D focusing array far-field eddy current detection probe is rotated along the rivet surface of the rivet, so that the array detection coil 4 placed at the hole edge in a linear array picks up eddy current field signals containing defect information inside the rivet to be detected in the far field region, and sends the signals to the signal conditioning module 8 and the display module 9.
The double-D focusing coil array eddy current testing method further comprises defect length evaluation, and specifically comprises the following steps of:
1) The detection signals of the array detection coil groups are respectively recorded as
A 0 、A 1 、A 2 ……A n (n=0,1,2,3……)；
2) Recording the total width of single detection coil as W, A qn =A n /A n-1 Let n=1, the threshold value be a q0 The following determination is made:
A qn ≥A q0 （1）
A qn ＜A q0 （2）
if the formula (1) is satisfied, performing the step 3); if the formula (2) is satisfied, performing the step 4);
3) So that n=n+1, at return to step 2);
4) The crack length L can be determined by the formula (3):
L=W×n （3）
the invention provides a double-D focusing coil array far-field eddy current probe, which comprises an excitation unit for generating a focusing excitation magnetic field, a detection unit for picking up detection signals and a shielding unit for shielding a direct coupling channel electromagnetic field, wherein the excitation unit comprises a double-D excitation coil inclined at a certain angle and a magnetic field structure, the detection unit comprises an array detection coil group and an array magnetic circuit structure, and the shielding unit is of a multilayer shielding structure. According to the double-D focusing coil array far-field eddy current probe, the double-D focusing coils are arranged to focus a magnetic field to the riveting piece, so that a low-frequency electromagnetic field generated by the coils can penetrate to a deeper depth, and deeper buried depth defects can be detected more easily; in addition, the array detection coils are arranged in a linear array, so that the defect length can be evaluated by using the array detection signals, and major accidents are avoided.
The foregoing examples merely illustrate specific embodiments of the invention, which are described in greater detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (2)
1. A detection method of a double-D focusing coil array far-field eddy current probe is characterized by comprising the following steps of: the double-D focusing coil array far-field eddy current probe comprises an excitation unit for generating a focusing excitation magnetic field, a detection unit for picking up detection signals and a shielding unit for shielding a direct coupling channel electromagnetic field, wherein the excitation unit comprises double-D excitation coils inclined at a certain angle and a magnetic field structure, the detection unit comprises an array detection coil group and an array magnetic circuit structure, the shielding unit comprises a first shielding piece, a second shielding piece and a third shielding piece, and the shielding unit is of a multi-layer shielding structure;
the double-D excitation coils are two D-shaped winding coils, the double-D excitation coils are symmetrically arranged along the axes of the excitation unit and the detection unit at a certain angle and have the same winding direction, the magnetic field structure is D-shaped, and the double-D excitation coils are wound in the magnetic field structure; the array detection coil set is a rectangular linear array coil set, the array magnetic circuit structure is a cuboid, and the array detection coil set is wound in the array magnetic circuit structure; the first shielding piece is coated on the double-D excitation coil and the magnetic field structure, the first shielding piece and the excitation unit are both fixedly arranged on the third shielding piece, the second shielding piece is coated on the array detection coil group and the array magnetic circuit structure, and the second shielding piece and the detection unit are both fixedly arranged on the third shielding piece; the excitation unit and the detection unit are placed across the rivet; the double-D excitation coils are simultaneously electrified with sinusoidal excitation signals with the same phase and frequency, and the turns of the double-D excitation coils are consistent;
the defect length evaluation method of the double-D focusing coil array far-field eddy current probe comprises the following steps:
1) The detection signals of the array detection coil groups are respectively recorded as
A 0 、A 1 、A 2 ……A n (n=0,1,2,3……)；
2) Recording the total width of single detection coil as W, A qn =A n /A n-1 Let n=1, the threshold value be a q0 The following determination is made:
A qn ≥A q0 （1）
A qn ＜A q0 （2）
if the formula (1) is satisfied, performing the step 3); if the formula (2) is satisfied, performing the step 4);
3) So that n=n+1, at return to step 2);
4) The crack length L can be determined by the formula (3):
L=W×n （3）；
the double-D focusing coil array eddy current detection method of the double-D focusing coil array far-field eddy current probe comprises the following steps:
step one: the double-D focusing excitation coil arranged on the riveting structural member to be detected is communicated with a low-frequency sine wave signal with the same frequency, and the double-D focusing excitation coil is arranged in the riveting structural member to be detected at a certain inclination angle to generate a focusing low-frequency magnetic field;
step two: the excitation unit and the detection unit are placed across the rivet, the double-D focusing array far-field eddy current detection probe is rotated along the surface of the rivet, so that the array detection coil which is arranged at the hole edge and is in a linear array picks up eddy current field signals containing internal defect information of the rivet to be detected in a far field region, and the signals are sent to the signal conditioning module and the display module.
2. The method for detecting the far-field eddy current probe with the double-D focusing coil array according to claim 1, wherein the method comprises the following steps of: the first shielding piece and the second shielding piece are made of aluminum alloy materials, the third shielding piece is made of copper materials, and the magnetic field structure and the array magnetic circuit structure are made of ferrite or silicon steel materials.
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