Aero-engine blade fatigue crack in-situ rapid detection probe and method

Abstract

The present application relates to the field of nondestructive testing, and discloses an aero-engine blade fatigue crack in-situ rapid eddy current detection probe and detection method. A profiled surface array flexible sweep frequency eddy current detection sensor is adopted, a profiled flexible skeleton which can be flexibly deformed and self-adapts to the surface of the blade back and blade basin of the blade to be detected is designed, and a multilayer flexible circuit board is provided, which is composed of at least three layers of flexible circuit boards. Each layer of flexible circuit board is provided with a plurality of array element coils arranged in an array, and the array element coils at the same longitudinal position on the three layers of flexible circuit boards are staggered with small spacing to form a three-circle cross shape. The surface of the uppermost layer of the multilayer circuit board is also provided with a transparent mucosa which can be adsorbed on the blade. A high-frequency time-sharing layered excitation working mode is adopted to obtain the detection signals of the array element coils on each layer of flexible circuit board. Whether there is a crack, the position, size and direction information of the crack are calculated by using multilayer detection signal inversion, and the detection efficiency and detection accuracy are greatly improved by one-time imaging.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nondestructive testing, in particular to an aero-engine blade fatigue crack in-situ rapid detection probe and a detection method thereof. BACKGROUND

[0002] It is known that the aero-engine is the heart of the aircraft, and its regular or situational detection is an essential measure to ensure flight safety. As the blade of the engine, it is the most prone to fatigue cracks due to the high-temperature, high-speed, and high-pressure working environment. The design, production, operation, and safety maintenance of the blade are the research direction of aviation researchers all over the world. In particular, the in-situ detection of the engine blade of the in-service aircraft is one of the research focuses. At present, the eddy current detection method is the best for in-situ detection of the engine blade, and a single probe is generally used for detection. In practice, due to the variable area ratio of the blade, the complex internal structure of the engine, and the poor visibility and operability of the objective detection status, the existing detection sensor is prone to probe disconnection or improper operation by the operator, which affects the reliability of the detection result. Based on this, in order to ensure flight safety and improve the detection efficiency and sensitivity of fatigue defects of the blade, the present application designs a new detection sensor and detection method to solve the above problems. SUMMARY

[0003] To solve the above problems, the present application provides an aero-engine blade fatigue crack in-situ rapid detection probe and a detection method thereof, which is implemented as follows:

[0004] An aero-engine blade fatigue crack in-situ rapid eddy current detection probe is specially used for in-situ rapid eddy current detection of the fatigue cracks on the surface of the blade of the aero-engine. The eddy current detection probe comprises a probe cable, a handle, a probe rod, and an eddy current detection sensor. The eddy current detection sensor is a profiled surface array flexible sweep frequency eddy current detection sensor. The profiled surface array flexible sweep frequency eddy current detection sensor comprises a profiled flexible framework and a plurality of layers of flexible circuit boards arranged on the profiled flexible framework.

[0005] The profiled flexible framework can be flexibly deformed and self-adaptable to the curved surface structure of the blade back and the blade basin surface of the blade to be detected or adaptable to the profiled surface of the specific detection area on the blade.

[0006] The plurality of layers of flexible circuit boards are stacked together. Each layer of flexible circuit board is provided with a plurality of array element coils arranged in an array, and the array element coils at the same longitudinal position on the plurality of layers of flexible circuit boards are arranged with a small interval and offset to form a multi-circle intersection shape.

[0007] A layer of transparent adhesive mucosa with adsorption is arranged on the surface of the uppermost layer of the plurality of layers of flexible circuit boards.

[0008] In situ detection, high-frequency time-sharing layered excitation mode is adopted, that is, the element coils at the same longitudinal position on the multi-layer flexible circuit board are excited by high-frequency in time-sharing manner, and the detection signals of the element coils on each layer of the flexible circuit board are obtained, and whether there is a crack and the position, size and direction information of the crack are calculated by using the multi-layer detection signals.

[0009] Further improvement, the multi-layer flexible circuit board is designed as a three-layer structure, and the specific detection steps include:

[0010] A, placement of the eddy current detection probe: according to the detection working condition of the blade to be detected, the eddy current detection probe is moved to the area to be detected, and the profiled surface array flexible swept-frequency eddy current detection sensor is placed on the surface of the back or basin of the blade to be detected in a conformal and complete manner;

[0011] B, eddy current lift-off detection: the uppermost layer of the multi-layer flexible circuit board is used to perform lift-off detection in advance to determine whether the eddy current detection sensor is well attached to the surface of the blade to be detected; when the lift-off value deviation is abnormal or greater than the set threshold, the eddy current detection sensor is removed and placed again, and the lift-off detection is performed again;

[0012] C, high-frequency time-sharing layered excitation: the element coils at the same longitudinal position on the three-layer flexible circuit board are excited by high-frequency in time-sharing manner, and the detection signals of the element coils on each layer of the flexible circuit board are obtained, and the obtained multiple sets of detection signals are fused;

[0013] D, signal processing and analysis: the three sets of detection signals obtained from the element coils at the same longitudinal position on the three-layer flexible circuit board are processed, the difference set and intersection set of each set of the obtained three sets of detection signals are sorted, the position of the fatigue crack is calculated by the intersection detection signal of the three sets of detection signals, and the determination result is verified, and the crack direction and size are determined by the difference set detection signal of each set of detection signals.

[0014] Further improvement, in the high-frequency time-sharing layered excitation of step C, the excitation signal frequencies loaded on the three-layer flexible circuit board are the same, and the lowermost layer and the middle layer of the flexible circuit board are respectively compensated for a small lift-off.

[0015] Further improvement, in the signal processing and analysis of step D, the processing of the signals includes removing the signal interference of the corresponding upper layer of the flexible circuit board from the detection signals of the lowermost layer and the middle layer of the flexible circuit board.

[0016] Compared with the prior art, the present application can obtain the following technical effects:

[0017] 1. The application combines the flexible profiling skeleton and the flexible array eddy current detection circuit board, and sets a layer of transparent mucosa on the surface of the array eddy current detection circuit board, so that the detection sensor and the blade to be detected can better adhere to realize better electromagnetic coupling, and the lifting detection of the eddy current signal is used to verify the adhesion effect in advance, greatly reducing the lifting interference during detection and improving the detection sensitivity.

[0018] 2. Compared with the conventional method of moving scanning with a single sensor, the conventional detection method has higher operation technical requirements for the detection personnel, and the crack direction evaluation needs to be determined according to the experience of the detection personnel, while the application adopts the array eddy current detection method, flexible stamping one-time imaging, and the operation is simpler, and the detection personnel can quickly identify the position and direction of the crack, realizing the synchronous improvement of detection efficiency, detection accuracy and discrimination accuracy.

[0019] 3. The application optimizes the design of the flexible array eddy current detection circuit board based on the profiling surface array flexible sweep frequency eddy current detection sensor, and designs it as a multilayer flexible circuit board, preferably a three-layer structure, and the three-layer flexible circuit board is stacked, each layer of the flexible circuit board is provided with a plurality of array element coils arranged in a surface array, the array element coils at the same longitudinal position on the three-layer flexible circuit board are arranged with small spacing and staggered to form a three-circle cross shape, and through high-frequency time-sharing layered excitation, multiple detection of the same defect point is realized, the spatial distribution rate of detection is improved, and the positioning and direction discrimination accuracy of crack detection is improved by using a multi-information inversion calculation method. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the application or the prior art or the description of the prior art required in the prior art description, it is obvious that for those skilled in the art, without creative labor, other drawings can also be obtained according to these drawings.

[0021] Figure 1 It is a schematic diagram of the blade structure for detection.

[0022] Figure 2 It is a schematic diagram of the structure of the eddy current detection probe of the application.

[0023] Figure 3 It is a schematic diagram of the blade body detection using the eddy current detection probe of the application.

[0024] Figure 4 It is a structure principle diagram of the multilayer flexible circuit board.

[0025] Figure 5 It is a structure sectional view of the array element coils at the same longitudinal position on the three-layer flexible circuit board.

[0026] Figure 6 Figure 3 is a schematic diagram of the superposition of the element coils on the same longitudinal position of the three-layer flexible circuit board.

[0027] Figure 7 Figure 4 is a brief flowchart of the detection method of the present application.

[0028] In the figure:

[0029] 10 - disc, 11 - blade;

[0030] 20 - eddy current detection sensor, 21 - profiled flexible skeleton, 22 - multilayer flexible circuit board, F1 - upper layer element coil, F2 - middle layer element coil, F3 - lower layer element coil, a, b, c - difference set area. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application.

[0032] The blade is one of the important components in the aero-engine. In the extreme working environment of high temperature and high speed, the aero-engine blade is prone to defects such as cracks. If these defects cannot be found and repaired in time, the defects will be enlarged, causing the blade to break and causing the crew to malfunction, affecting flight safety. In the detection of the engine blade, due to the complex structure of the engine, it is not suitable to be repeatedly disassembled, so the detection of the engine structure is generally in-situ detection. For the blade and other components with complex detection environment and certain curvature, if a traditional single sensor is used for mobile scanning, the detection efficiency is low, and the probe is easy to have a lift-off from the detection surface, causing inconsistent sensitivity and affecting the reliability of the detection result. With the development of electromagnetic nondestructive testing technology and the progress of production process, flexible array eddy current detection technology gradually appears in the field of view of researchers. By using FPCB, the detection is performed by attaching it to the detection surface. Although this method has good adaptability to special-shaped workpieces, it is still inevitable that improper attachment or limited detection component sensitivity will occur. Based on this, the present application researches an in-situ rapid eddy current detection probe and a detection method thereof, striving to realize in-situ, rapid, accurate and effective detection of the fatigue cracks of the aero-engine blade. The specific content is as follows:

[0033] The application discloses a kind of aero-engine blade fatigue crack in situ rapid eddy current detection probe, it is specially used to carry out in situ rapid eddy current detection to the blade fatigue crack on the surface of blade 11 on aero-engine blade disc 10, the eddy current detection probe includes probe cable, handle, probe rod and eddy current detection sensor 20.

[0034] The probe rod is designed as a bent rod structure that can adapt to the working condition of the blade to be detected, and a universal rotating seat is designed at the connecting part of the probe rod and the eddy current detection sensor 20, so that the angle of the probe rod and the eddy current detection sensor 20 can be adjusted according to the detection needs.

[0035] The eddy current detection sensor 20 is a profiled surface array flexible sweep-frequency eddy current detection sensor, which comprises a profiled flexible skeleton 21 and a plurality of layers of flexible circuit boards 22 arranged on the profiled flexible skeleton 21.

[0036] The profiled flexible skeleton 21 can be flexibly deformed and self-adapted to the curved surface structure of the blade back and blade basin surface of the blade 11 to be detected or adapted to the profile of a specific detection area on the blade blade body; in the embodiment, the size and structure shape of the profiled flexible skeleton 21 are adapted to the size of the complete blade 11 blade body, and in other embodiments, if the detection is only for a key detection site on the blade blade body, the profiled flexible skeleton 21 can be designed according to the profile of the specific detection area, and the design size is adapted to the structure to reduce the number of element coils on the eddy current detection sensor 20 as much as possible, reduce the cost of the equipment, and at the same time, reduce the volume of the sensor and increase the flexibility of the sensor in moving in the narrow space of the aero-engine structure.

[0037] Reference is made to the drawings Figures 4-6 In the embodiment, the plurality of layers of flexible circuit boards 22 are designed as a three-layer structure, i.e., three layers of flexible circuit boards are stacked, each layer of flexible circuit board is provided with a plurality of element coils arranged in an array, and the element coils at the same longitudinal position on the three layers of flexible circuit boards are arranged in a three-circle intersection shape with small spacing and staggered, and in the embodiment, the upper layer of element coils F1, the middle layer of element coils F2 and the lower layer of element coils F3 are stacked in sequence. In other embodiments, the plurality of layers of flexible circuit boards can also be designed as a double-layer or four-layer structure.

[0038] The surface of the uppermost layer of the plurality of layers of circuit boards 21 is provided with a layer of transparent adhesive film with adsorption;

[0039] During in-situ detection, a high-frequency time-sharing layered excitation mode is adopted, i.e., the element coils at the same longitudinal position on the three layers of flexible circuit boards are excited in a time-sharing high-frequency mode, and the detection signals of the element coils on each layer of flexible circuit board are obtained, and whether there is a crack and the position, size and direction information of the crack are calculated by using the plurality of layers of detection signals.

[0040] Further improved, the specific detection steps include:

[0041] A, placement of the eddy current detection probe: according to the detection working condition of the blade to be detected, the eddy current detection probe is moved to the area to be detected, and the profiled surface array flexible swept-frequency eddy current detection sensor is placed on the surface of the blade back or blade basin to be detected in a conformal and complete manner;

[0042] B, eddy current lift-off detection: the uppermost flexible circuit board of the multi-layer circuit board is used to perform lift-off detection in advance, to determine whether the eddy current detection sensor is well attached to the surface of the blade to be detected; when the lift-off value deviation is abnormal or greater than the set threshold, the eddy current detection sensor is removed and placed again, and the lift-off detection is performed again; the pre-lift-off detection avoids the detection error caused by the non-attachment of the eddy current detection sensor to the blade, reduces the difficulty of data processing, effectively improves the work efficiency, and improves the accuracy of the detection results.

[0043] C, high-frequency time-sharing layered excitation: the array element coils at the same longitudinal position on the three flexible circuit boards are excited in time-sharing high-frequency, and the detection signals of the array element coils on each flexible circuit board are obtained, and the obtained multiple sets of detection signals are fused; through time-sharing layered excitation, multiple sets of superimposed detection signals at the same longitudinal position are obtained, multiple detection of the same defect point is realized, and the spatial distribution rate of detection is improved.

[0044] D, signal processing and analysis: three sets of detection signals obtained from the array element coils at the same longitudinal position on the three flexible circuit boards are processed, the difference set and intersection set of each set of the obtained three sets of detection signals are sorted, the position of the fatigue crack is calculated through the intersection detection signal of the three sets of detection signals, and the determination result is verified, and the crack direction and size are determined through the difference set detection signal of each set of detection signals.

[0045] The present application adopts a special profiled surface array flexible sweep eddy current detection sensor, which has the following advantages: first, the flexible profiled structure combined with the surface array eddy current detection can well adhere to the blade to be detected, overcoming the lift-off deviation caused by the curvature; second, the surface array detection method can scan and image at one time, compared with the traditional single probe moving scanning method, the present application is more simple to operate, and different detection personnel with different detection experience can better perform the detection work, and the one-time imaging method greatly improves the detection efficiency and facilitates the detection personnel to analyze the signal diagram; third, a special flexible circuit board design is adopted, and a multi-layer flexible circuit board staggered and overlapped structure is used, wherein the flexible circuit board can be a three-layer or four-layer or five-layer structure, in the embodiment, three-layer flexible circuit boards are overlapped, the array element coils at the same longitudinal position on the three-layer flexible circuit boards are arranged in a small interval and staggered to form a three-circle intersection shape, a plurality of detection signals with signal overlap are obtained by time-sharing high-frequency excitation of the array element coils at the same longitudinal position, and the multi-information inversion calculation method is used for crack detection positioning and trend discrimination, which greatly improves the crack feature discrimination precision.

[0046] Further improved, in the high-frequency time-sharing layered excitation of step C, the excitation signal frequencies loaded by the three-layer flexible circuit boards are the same, and the lowermost flexible circuit board and the middle flexible circuit board are respectively subjected to corresponding micro-lift compensation. In the signal processing and analysis of step D, the processing of the signal includes removing the signal interference of the corresponding upper flexible circuit board from the detection signals of the lowermost flexible circuit board and the middle flexible circuit board. Through the micro-lift compensation and the removal of the detection noise, the preset detection conditions of the three-layer flexible circuit boards are ensured to be the same, the detection parameter setting is standardized, and the reliability of the detection result is improved.

[0047] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An aero-engine blade fatigue crack in-situ rapid eddy current detection probe, which is specially used for in-situ rapid eddy current detection of fatigue cracks on the surface of aero-engine blade airfoils, and comprises a probe cable, a handle, a probe rod and an eddy current detection sensor, characterized in that: the eddy current detection sensor is a profiled face array flexible swept-frequency eddy current detection sensor, which comprises a profiled flexible framework and a plurality of layers of flexible circuit boards arranged on the profiled flexible framework; the profiled flexible framework is flexible and deformed and self-adapts to the curved surface structure of the back and the basin of the airfoil of the blade to be detected or adapts to the profile of a specific area to be detected on the airfoil of the blade; the plurality of layers of flexible circuit boards are stacked together, each layer of flexible circuit board is provided with a plurality of array element coils arranged in an array, and the array element coils at the same longitudinal position on the plurality of layers of flexible circuit boards are arranged with small spacing and staggered to form a multi-circle cross shape; the surface of the uppermost layer of the plurality of layers of flexible circuit boards is provided with a layer of transparent adhesive film with adsorption; during in-situ detection, a high-frequency time-sharing layered excitation mode is adopted, that is, the array element coils at the same longitudinal position on the plurality of layers of flexible circuit boards are excited in time-sharing high-frequency mode, and the detection signals of the array element coils on each layer of flexible circuit board are obtained, and whether there is a crack and the position, size and direction of the crack are calculated by using the multi-layer detection signals. The plurality of layers of flexible circuit boards are designed as a three-layer structure. The specific detection steps include: A. Placement of the eddy current detection probe: according to the detection conditions of the blade to be detected, the eddy current detection probe is moved to the area to be detected, and the profiled face array flexible swept-frequency eddy current detection sensor is placed on the surface of the back or the basin of the blade to be detected in a self-adapting and complete manner; B. Eddy current lift-off detection: the uppermost layer of flexible circuit board of the plurality of layers of circuit boards is used to perform lift-off detection in advance to determine whether the eddy current detection sensor is well attached to the surface of the blade to be detected; when the lift-off value deviates abnormally or is greater than a set threshold, the eddy current detection sensor is removed and placed again, and the lift-off detection is performed again; C. High-frequency time-sharing layered excitation: the array element coils at the same longitudinal position on the three layers of flexible circuit boards are excited in time-sharing high-frequency mode, and the detection signals of the array element coils on each layer of flexible circuit board are obtained, and the obtained multiple sets of detection signals are fused; 2. An aeroengine blade fatigue crack in situ rapid eddy current probe according to claim 1, characterized in that, D. Signal processing and analysis: the three sets of detection signals obtained from the array element coils at the same longitudinal position on the three layers of flexible circuit boards are processed, the difference set and the intersection set of each set of detection signals are sorted, the position of the fatigue crack is calculated by the intersection detection signal of the three sets of detection signals, and the calculation result is verified, and the direction and size of the crack are determined by the difference set detection signal of each set of detection signals.

3. A method for in situ rapid eddy current inspection of fatigue cracks in an aeroengine blade using the eddy current inspection probe as claimed in claim 2, characterized in that, In the high-frequency time-sharing layered excitation of step C, the excitation signal frequencies of the three layers of flexible circuit boards are the same, and the lowermost layer of flexible circuit board and the middle layer of flexible circuit board are respectively subjected to corresponding small lift-off compensation. ​ ​ ​ ​ 4. An aeroengine blade fatigue crack in situ rapid eddy current testing method according to claim 3, characterized in that, ​ 5. An aeroengine blade fatigue crack in situ rapid eddy current testing method according to claim 4, characterized in that, In the signal processing and analysis of step D, the processing of the signal includes removing the signal interference of the corresponding upper flexible circuit board from the detection signal of the lowermost flexible circuit board and the intermediate flexible circuit board respectively.

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