CN114235951B - Crack fault acoustic diagnosis method and device for engine air inlet casing support plate - Google Patents
Crack fault acoustic diagnosis method and device for engine air inlet casing support plate Download PDFInfo
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- CN114235951B CN114235951B CN202111432805.XA CN202111432805A CN114235951B CN 114235951 B CN114235951 B CN 114235951B CN 202111432805 A CN202111432805 A CN 202111432805A CN 114235951 B CN114235951 B CN 114235951B
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Abstract
The application provides an acoustic diagnosis method for crack faults of an engine air inlet casing support plate, which comprises the following steps: striking an engine intake casing stationary support plate to generate an acoustic signal; acquiring a force signal impacting an engine air inlet casing fixed support plate and an acoustic signal generated by the engine air inlet casing fixed support plate, and processing the force signal and the acoustic signal through a transfer function method to obtain an acoustic frequency response signal; comparing the acoustic frequency response signals of the engine air inlet casing fixed support plate with the acoustic frequency response signals of the engine air inlet casing fixed support plate in the database, and judging that the engine air inlet casing fixed support plate is cracked if the frequency difference value of the first peak value of the two acoustic frequency response signals exceeds a threshold value, otherwise, not generating cracks. Compared with the traditional fault diagnosis method, the crack fault acoustic diagnosis method is simpler and more efficient, and can effectively identify crack faults in the support plate and at the junction surface of the structure.
Description
Technical Field
The application belongs to the technical field of automatic control, and particularly relates to a method and a device for online identification of gap link characteristic parameters based on line segment fitting.
Background
The air inlet casing is used as a main bearing and air inlet part at the front end of the aeroengine, and has the functions of rectifying incoming air flow, ensuring that the air flow can meet the use requirement of the air compressor, and enabling the air flow to flow through the bent flow passage with minimum total pressure loss and minimum aerodynamic resistance. The engine air inlet casing has the problems of large load and light weight, and meanwhile, the air inlet casing is easy to corrode and vibrate under the working conditions of high pressure, high speed and various loads for a long time, so that the fixed support plate of the air inlet casing is cracked, and further the support plate is broken, thereby causing flight accidents.
Because the aeroengine is complex in structure, and the crack forms of the air inlet casing support plate are various, the traditional detection method such as hole detection, fluorescence, vibration, noise monitoring, ultrasonic flaw detection and the like can have several problems when diagnosing the crack faults of the air inlet casing support plate:
1) The nondestructive inspection detection method for hole detection, fluorescence and the like is a common method for detecting faults, such as structural cracks, corrosion, tearing and the like in the engineering field, and is also a common detection means for the structural state fixed inspection of an aeroengine, but the detection method is applied to the detection of cracks of a support plate of an air inlet casing of the engine, and has the following problems:
1.1 The accuracy of nondestructive flaw detection such as hole detection and fluorescence is limited by the operation accuracy and judgment capability of an inspector, so that diagnosis errors can be caused by human factors, and the detection reliability is reduced;
1.2 Hole detection, fluorescence and other nondestructive flaw detection can only detect crack states on the surface of the support plate, and crack states in the structure and at the junction surface of the structure cannot be identified;
2) Vibration and noise monitoring are also fault diagnosis methods commonly used for large-scale equipment. The equipment fault diagnosis can be realized by identifying the vibration and noise characteristic signals generated in the running process of the equipment and extracting and separating the state information of the equipment in the characteristic signals. However, the following problems exist when the method is applied to the detection of cracks of the support plate of the air inlet casing of the engine:
2.1 The whole structure of the aero-engine is complex, the test condition is bad, and the potential safety hazard of the test exists when vibration and noise points are added in the test state;
2.2 The characteristics of the whole machine vibration and noise signals of the aero-engine are complex, the structure of the air inlet casing support plate is small, the energy of the generated vibration and noise signals is weak, and the characteristic signals of the air inlet casing support plate are difficult to identify from the vibration and noise signals of the whole machine;
3) Structural modal analysis is also a common means in structural failure diagnosis. The structural failure diagnosis can be realized by comparing the modal information obtained by the method for identifying and analyzing the modal with the modal information of the initial state of the structure. However, the following problems exist when the method is applied to the detection of cracks of the support plate of the air inlet casing of the engine:
3.1 The number of the air inlet casing support plates of the engine is large, vibration measuring points are required to be arranged on each support plate to acquire state information of all support plates, and a modal test is carried out on each support plate, so that the test flow and the test method are complex;
3.2 The whole structure of the aero-engine is complex, and the difficulty of arranging vibration measuring points on all support plates is high in the whole state;
4) Ultrasonic inspection is also a common method in structural failure diagnosis. However, the following problems exist when the method is applied to the detection of cracks of the support plate of the air inlet casing of the engine:
4.1 The ultrasonic flaw detection is required to be determined in advance according to flaw detection sensitivity and flaw judgment standards, and the flaw state on the surface of the support plate cannot be effectively identified due to overlarge sensitivity or overlarge sensitivity;
4.2 Under the state of the whole machine, ultrasonic flaw detection can only detect the crack state of the surface of the support plate, and crack characteristics in the structure and at the junction surface of the structure cannot be identified;
5) The fast fourier transform and the short-time fourier transform are commonly used test data processing means in signal processing, and the characteristic information of the signals is obtained by decomposing the time domain signals into components with different frequencies. In the test scheme, the applied excitation has randomness, and the acoustic response signal of the support plate has weak energy and short duration, so that the characteristic signal of the support plate cannot be effectively identified by the traditional Fourier transform analysis method.
Disclosure of Invention
The application aims to provide an acoustic diagnosis method and device for crack faults of an engine air inlet casing support plate, so as to solve or reduce at least one problem.
In one aspect, the application provides an acoustic diagnostic method for crack failure of an engine intake casing support plate, the method comprising:
Striking an engine intake casing stationary support plate to generate an acoustic signal;
Acquiring a force signal impacting an engine air inlet casing fixed support plate and an acoustic signal generated by the engine air inlet casing fixed support plate, and processing the force signal and the acoustic signal through a transfer function method to obtain an acoustic frequency response signal;
Comparing the acoustic frequency response signals of the engine air inlet casing fixed support plate with the acoustic frequency response signals of the engine air inlet casing fixed support plate in the database, and judging that the engine air inlet casing fixed support plate is cracked if the frequency difference value of the first peak value of the two acoustic frequency response signals exceeds a threshold value, otherwise, not generating cracks.
Further, before striking the engine intake casing stationary support plate to generate an acoustic signal, the method further comprises: environmental background noise is collected.
Further, after the acoustic signals generated by the engine air inlet casing fixing support plate are collected, the acoustic signals are compared with the background noise, and in a certain frequency range, the acoustic signals higher than the background noise reservation value are effective signals.
Further, the frequency range is 0-1000 Hz.
Further, the predetermined value is not less than 3dB.
Further, the process of processing the force signal and the acoustic signal by a transfer function method to obtain an acoustic frequency response signal includes:
locating a time at which the fixed-plate acoustic response signal occurs based on a time-domain analysis of the force signal;
Selecting a certain length of analysis time based on the duration of the acoustic response signal;
Based on a transfer function method, the collected force signals are normalized to acoustic response signals of the support plate, influence of random excitation on the acoustic response signals of the support plate is eliminated, and characteristic signals of the support plate are obtained.
Further, the expression of the transfer function is as follows:
wherein P xy (f) is the self spectrum of the input end, and P xx (f) is the cross spectrum of the output end.
In another aspect, the present application provides an apparatus for implementing the crack failure acoustic diagnosis method of the engine intake casing support plate according to any one of the above, the apparatus comprising:
An acoustic sensor for acquiring acoustic signals;
A hammer for striking the fixed support plate to cause the fixed support plate to generate an acoustic signal;
the acquisition system is used for processing the acoustic signals acquired by the acoustic sensor and the force signals striking the fixed support plate;
The handheld bracket is respectively connected with the acoustic sensor and the force hammer, and the handheld bracket sends the acoustic sensor and the force hammer to the vicinity of the fixed support plate through the outside of the engine; and
And the sensor fixing support is fixedly connected with the fixing support plate and is used for supporting and fixedly connecting an acoustic sensor and a hand-held support with a hammer point.
The crack fault diagnosis method and the crack fault diagnosis device provided by the application realize effective, rapid and accurate identification of the crack fault of the fixing support plate of the engine air inlet casing, and have the main advantages that:
1) When the traditional fault diagnosis method is applied to diagnosis of crack faults of the fixed support plate of the air inlet casing of the aeroengine, the problems that the diagnosis reliability is poor, crack characteristics in the structure and at the junction surface of the structure cannot be identified, the diagnosis method is complex and the like exist;
2) Because excitation has randomness, and the acoustic response signal of the support plate has weaker energy and shorter duration, the characteristic signal of the support plate cannot be effectively identified by the traditional Fourier transform analysis method, and the characteristic signal of the support plate can be effectively identified by processing the characteristic of the acoustic response signal of the support plate;
3) The fault diagnosis device can realize simple and efficient diagnosis of crack faults of the engine air inlet casing support plate under the condition of an external field test.
Drawings
In order to more clearly illustrate the technical solution provided by the present application, the following description will briefly refer to the accompanying drawings. It will be apparent that the figures described below are merely some embodiments of the application.
FIG. 1 is a schematic diagram of a method for diagnosing crack faults of an engine air inlet casing support plate.
Fig. 2 is a schematic diagram of an engine intake casing support plate crack fault diagnosis device according to the present application.
Fig. 3 is a plot of acoustic frequencies of a support plate obtained by a conventional fourier transform method.
Fig. 4 is a plot of acoustic frequencies of a support plate obtained by the acoustic diagnostic method of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application become more apparent, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application.
Aiming at the crack fault diagnosis of the fixed support plate of the air inlet casing of the aeroengine, the application provides a crack fault acoustic diagnosis method and a fault diagnosis device, which can effectively, accurately and rapidly identify the crack fault of the support plate of the air inlet casing.
In the process of endurance test of the aero-engine, the air inlet casing works under the test working condition of high speed and high load for a long time, and the support plate can generate fatigue cracks, so that the test safety and the reliability of the engine are seriously affected. The acoustic signal is used as a signal capable of reflecting state information of structural features, and when the support plate has crack failure, the structural features of the fixed support plate can be changed, so that the acoustic signal features generated by stress of the fixed support plate are changed. According to the characteristic, the application provides an acoustic diagnosis method suitable for crack faults of the fixing support plate of the air inlet casing of the aeroengine, and the faults of the cracks of the support plate of the air inlet casing of the aeroengine can be effectively identified.
As shown in fig. 1 and fig. 2, before the test, a test database of a brand new air inlet casing support plate is firstly established, and the diagnosis of the crack fault of the fixed support plate is realized through the comparison of test data characteristics.
The test system mainly comprises an acoustic sensor 11, a hammer 13 and an acoustic data acquisition system 12. Before the test, the force hammer 13 and the acoustic sensor are synchronously connected into a data acquisition system, and the system is ensured to acquire acoustic signals stably and effectively. Before the formal test of the application is developed, background noise of the test environment is recorded.
In the test, the acoustic sensor 11 is first fixed, and each support plate is tapped in sequence by the hammer 13. The acoustic data acquisition system 12 is used for acquiring the acoustic response signals generated by knocking the fixed support plate, comparing the acoustic response signals with the background noise signals, and carrying out test again on the invalid data, wherein the acoustic signal data which are at least 3dB higher than the background noise are effective data in the frequency range of 0-1000 Hz.
Comparing the screened effective data with the frequency of occurrence of the first peak value of the sound response signal of the sound fixing support plate, wherein the difference value of the effective data and the frequency of occurrence of the first peak value is within a certain frequency range (determined according to a test database of a brand-new casing support plate), judging that the sound fixing support plate is sound, otherwise, judging that the sound fixing support plate has crack failure. According to the application, the diagnosis of the crack fault of the support plate can be effectively realized by comparing the occurrence frequency of the first peak value of the sound response signals of the target support plate and the sound support plate.
In addition, the Fourier transform analysis method is a data processing analysis means commonly used in fault signal processing, and mainly comprises fast Fourier transform and short-time Fourier transform, and the principle is to decompose time domain data of a period of time into sinusoidal components of different frequencies. In the present application, the following problems are faced when the fast fourier transform or the short-time fourier transform is applied to process the fault signal because the acoustic signal generated by the fixed-board strike has a short duration, the acoustic response signal has weak energy and the applied excitation is random: 1) When the time length of the selected and analyzed data is long, the crack fault signals of the support plate cannot be accurately identified under certain excitation conditions; 2) When the time length of the selected and analyzed data is short, the analysis precision is poor.
Under the background, the method of the application further provides effective extraction of the characteristic signals of the support plate, and the specific process comprises the following steps:
firstly, positioning the occurrence time of acoustic response signals of the support plate based on time domain analysis of force signals;
Secondly, selecting a suitable analysis duration, which may typically be 0.2s or 0.5s, based on the duration of the acoustic response signal;
finally, based on a transfer function method, the acquired force signals are subjected to normalization processing on the acoustic response signals of the support plate, the influence of random excitation on the acoustic response signals of the support plate is eliminated, the characteristic signals of the support plate are obtained, and further diagnosis on crack faults of the support plate is realized.
Wherein, the expression form of the transfer function is as follows:
Wherein: p xy (f) is the self spectrum of the input end, and P xx (f) is the cross spectrum of the output end.
As shown in fig. 3 and 4, under random excitation, the characteristic signals of the support plate cannot be effectively identified by the conventional fourier transform analysis method, and the characteristic signals of the support plate can be obviously found to be about 250Hz by applying the method of the application.
Finally, the frequency curve in fig. 4 is compared with the data in the database, and a crack is generated when the frequency curve is changed, but the frequency curve is generally low.
Under the whole state of the aeroengine, the air inlet casing is positioned in the air inlet channel, and the conventional means is that a tester drills into the air inlet channel to diagnose the crack state of the support plate, and the test method is complex and has lower efficiency. Therefore, the application further provides a diagnosis device suitable for the method based on the diagnosis method, so that the diagnosis scheme is simpler and more convenient, and the diagnosis efficiency is improved.
As shown in fig. 1 and 4, the diagnostic device provided by the present application is mainly composed of an acoustic sensor 11, an acquisition system 12 (not shown in fig. 4), a hammer 13, a sensor fixing bracket 14, and a hand-held bracket 15. The sensor fixing bracket is a fixing device of an acoustic sensor and a handheld bracket, so that the state of the microphone is stable and shaking is avoided when a diagnostic test is carried out; the hand-held support is used for fixing the force hammer and the sensor respectively, the force hammer and the sensor can be stretched into the support plate by the aid of the hand-held support, test staff is not required to drill into the air inlet channel, detection of crack states of the support plate can be carried out, the diagnosis scheme is simpler and more convenient, and diagnosis efficiency can be improved.
The crack fault diagnosis method and the crack fault diagnosis device provided by the application realize effective, rapid and accurate identification of the crack fault of the fixing support plate of the engine air inlet casing, and have the main advantages that:
1) When the traditional fault diagnosis method is applied to diagnosis of crack faults of the fixed support plate of the air inlet casing of the aeroengine, the problems that the diagnosis reliability is poor, crack characteristics in the structure and at the junction surface of the structure cannot be identified, the diagnosis method is complex and the like exist;
2) Because excitation has randomness, and the acoustic response signal of the support plate has weaker energy and shorter duration, the characteristic signal of the support plate cannot be effectively identified by the traditional Fourier transform analysis method, and the characteristic signal of the support plate can be effectively identified by processing the characteristic of the acoustic response signal of the support plate;
3) The fault diagnosis device can realize simple and efficient diagnosis of crack faults of the engine air inlet casing support plate under the condition of an external field test.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (6)
1. An acoustic diagnostic method for crack failure of an engine intake casing support plate, the method comprising:
Striking an engine intake casing stationary support plate to generate an acoustic signal;
The method comprises the steps of collecting a force signal impacting an engine air inlet casing fixing support plate and an acoustic signal generated by the engine air inlet casing fixing support plate, processing the force signal and the acoustic signal through a transfer function method to obtain an acoustic frequency response signal, wherein the process comprises the following steps: locating a time at which the fixed-plate acoustic response signal occurs based on a time-domain analysis of the force signal; selecting a certain length of analysis time based on the duration of the acoustic response signal; based on a transfer function method, normalizing the acquired force signals to acoustic response signals of the support plate, eliminating the influence of random excitation to the acoustic response signals of the support plate, and acquiring characteristic signals of the support plate, wherein the expression form of the transfer function is as follows:
Wherein P xy (f) is the self spectrum of the input end, and P xx (f) is the cross spectrum of the output end;
Comparing the acoustic frequency response signals of the engine air inlet casing fixed support plate with the acoustic frequency response signals of the engine air inlet casing fixed support plate in the database, and judging that the engine air inlet casing fixed support plate is cracked if the frequency difference value of the first peak value of the two acoustic frequency response signals exceeds a threshold value, otherwise, not generating cracks.
2. The method for acoustically diagnosing a crack failure in an engine intake housing mount according to claim 1, further comprising, before striking the engine intake housing mount to generate an acoustic signal: environmental background noise is collected.
3. The acoustic diagnosis method for crack failure of engine intake casing support plate according to claim 2, wherein after the acoustic signal generated by the engine intake casing fixed support plate is collected, the acoustic signal is compared with the background noise, and in a certain frequency range, the acoustic signal higher than the predetermined value of the background noise is an effective signal.
4. The acoustic diagnostic method for crack failure of an engine intake casing support plate according to claim 3, wherein the frequency range is 0 to 1000Hz.
5. The crack failure acoustic diagnostic method of an engine intake casing support plate according to claim 3, wherein the predetermined value is not less than 3dB.
6. An apparatus for implementing the crack failure acoustic diagnosis method of the engine intake casing support plate according to any one of claims 1 to 5, characterized by comprising:
an acoustic sensor (11) for acquiring acoustic signals;
A hammer (13) for striking the fixed support plate to cause the fixed support plate to generate an acoustic signal;
an acquisition system (12) for processing acoustic signals acquired by the acoustic sensor and force signals impinging on the stationary support plate;
A hand-held bracket (15) respectively connected with the acoustic sensor (11) and the force hammer (13), wherein the hand-held bracket (15) sends the acoustic sensor (11) and the force hammer (13) to the vicinity of the fixed support plate through the outside of the engine; and
The sensor fixing support (14) is fixedly connected with the fixing support plate, and the sensor fixing support (14) is used for supporting and fixedly connecting the acoustic sensor (11) and the hand-held support (15) with the point of the hammer (13).
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111432805.XA CN114235951B (en) | 2021-11-29 | Crack fault acoustic diagnosis method and device for engine air inlet casing support plate |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111432805.XA CN114235951B (en) | 2021-11-29 | Crack fault acoustic diagnosis method and device for engine air inlet casing support plate |
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| CN114235951A CN114235951A (en) | 2022-03-25 |
| CN114235951B true CN114235951B (en) | 2024-07-05 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104870969A (en) * | 2012-12-13 | 2015-08-26 | 斯奈克玛 | Method and device for acoustically detecting a malfunction of a motor having an active noise control |
| CN107478729A (en) * | 2017-09-22 | 2017-12-15 | 沈阳工业大学 | The acoustic emission detection method of fluid machinery blade multiple crackses |
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104870969A (en) * | 2012-12-13 | 2015-08-26 | 斯奈克玛 | Method and device for acoustically detecting a malfunction of a motor having an active noise control |
| CN107478729A (en) * | 2017-09-22 | 2017-12-15 | 沈阳工业大学 | The acoustic emission detection method of fluid machinery blade multiple crackses |
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