CN102538950A - Acoustic testing method for inherent frequency of engine part - Google Patents
Acoustic testing method for inherent frequency of engine part Download PDFInfo
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- CN102538950A CN102538950A CN2010106026238A CN201010602623A CN102538950A CN 102538950 A CN102538950 A CN 102538950A CN 2010106026238 A CN2010106026238 A CN 2010106026238A CN 201010602623 A CN201010602623 A CN 201010602623A CN 102538950 A CN102538950 A CN 102538950A
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Abstract
The invention discloses an acoustic testing method for inherent frequency of an engine part. The method is characterized by comprising the following steps of: putting a tested part (1) on a working platform (3); and putting a sound wave induction sensor (4) at a distance of 3 to 5 centimeters away from the tested part (1), exciting the tested part (1) by using a small wooden hammer, acquiring sound wave produced by the tested part by using the sound wave induction sensor (4), making the sound wave sequentially pass through a preamplifier (5) and a signal acquisition and processing device (6), and outputting the frequency of each order of the tested part by a computer (7). The method has the advantages of simplicity in operation, no damage to the part, broad testing band and accurate testing result.
Description
Technical field
The present invention relates to the field tests of part frequency, a kind of acoustic testing method of engine component natural frequency is provided especially.
Background technology
The existing quiet frequency method of testing of aerial motor spare part mainly contains two kinds, and a kind of is the shaking table resonant method, and another kind is the hammering method of touch sensor.
Shaking table resonance frequency measurement method, be with parts under the exciting force effect of adjustable frequency, produce forced vibration, when excitation force frequency equals its natural frequency, amplitude will sharply increase, this moment, part got into resonance state.The part vibration frequency that under resonance state, records is exactly its natural frequency.Electromagnetic vibration generator system is a kind of set of equipments, generally is made up of with manipulation control desk two large divisions the vibration stage body.Its test macro is seen Fig. 2, and shaking table belongs to the contact vibrator, surveys natural frequency with its exciting parts, and parts pass through clamps on shaking table, and vibrates with shaking table.The electromagnetic vibration generator system scope of application is wider, is current a kind of excitational equipment comparatively commonly used.Some engine production factories also are decided to be the standard device that blade is surveyed natural frequency with electromagnetic vibration generator system.
Electromagnetic vibration generator system is applicable to that testing laboratory uses, and must have special-purpose anchor clamps to match.Requirement for anchor clamps is also higher, and anchor clamps will have enough rigidity with shaking table and both connection, if anchor clamps and table top loose contact, be connected not firm or all can influence frequency-measurement accuracy with table top rigidity deficiency.The machining precision of clamp structure, clamping mode, fixture block and wearing and tearing, crackle also can influence frequency-measurement accuracy.When measuring some irregular parts (like wheel disc), be difficult to design suitable anchor clamps.And shaking table frequency measurement scope is generally below the 3000Hz by the device parameter restriction.Therefore, survey the engine part natural frequency with electromagnetic vibration generator system and have certain limitation.The method mainly is fit to engine blade and the small-sized clamping parts that are simple and easy to are difficult to realize test for large complicated member.
The hammering method vibration measuring is ancient and classical vibration measuring method, and the past, this vibration measuring method secular stagnation is development not owing to there is not dynamic analysis system.Nineteen sixty-five has proposed the appearance of Fast Fourier Transform (FFT) (FFT) computing method and robot calculator, and arithmetic speed is improved greatly, also makes the hammering method vibration measuring obtain fast development.
When surveying the vibration characteristics of engine component with hammering method, single test can obtain bulk information, through data processing, can directly provide the parameters such as multistage Natural Frequency of Vibration, the vibration shape, modal damping ratio and modal mass of engine component.
It is different with conventional method that hammering method is made vibration test, and it is without various electronic devices such as vibrator, signal sources, only with the hand hammer of band force transducer and the sensor and the response data acquisition and analysis instrument of measurement response.Hammering engine component firmly, the response of record impulse force and part.By the fast Fourier transform (FFT) of number extraction system, measure dynamic Characteristics of Structure rapidly then, obtain modal parameter through data processing.But when hammering method is tested less parts natural frequency, receive the sensor additional mass influence that sticks on the parts, error is bigger.During for parts frequency measurement in batch, need paste sensor repeatedly, and the sensor paste position, bigger to the frequency measurement structure influence.
Update along with engine; The parts of engine are more and more integrated, complicated; Increasing like complex structural members such as blisk proportion in engine of new generation; And complicated like this member receives structure and mounting condition restriction thereof, can't adopt traditional natural frequency method of testing.
And for these blade frequency measurement work in batch; Test first three, during the quadravalence natural frequency, the shaking table resonant method need scan high band from low-frequency range, and is consuming time longer; And general shaking table frequency range is below 3000Hz; The natural frequency that is higher than 3000Hz just can't be tested, if adopt the frequency measurement of acceleration transducer hammering method, need paste the installation testing sensor repeatedly; The transport function of making every effort to achieve sensor and vibration measuring wound sensor through calculating obtains the parts natural frequency, and the quality of transport function receives that the effect of power hammer is too big, the influence of action time and vibration-measuring sensor installation site is very big.The too big parts that damage easily of power hammer acting force, power too brief biography delivery function quality is just bad, and high order of frequency encourages to come out yet.Metal parts that frequency is higher or widget frequency are higher; Requirement power hammer is short more good more action time; And the time length of power hammer effect is relevant with the material of tup, more hard tup action time shorter (steel hammer head), but must certain damage be arranged to parts with harder tup.Moreover the installation site of vibration-measuring sensor is also very big to frequency measurement result influence, if vibration-measuring sensor just can't pick up vibration signal when being installed on the parts vibration nodel line, also just can not survey the natural frequency of parts.
Summary of the invention
The object of the present invention is to provide a kind of acoustic testing method of engine component natural frequency; Measure the anchor clamps complicacy that the natural frequency of the labyrinth parts of producing in batch exists with the hammering method that solves shaking table resonant method and touch sensor; Measurement range is limited, and the big problem of measuring result error.
The invention provides a kind of acoustic testing method of engine component natural frequency; The principle of its test process is following: at first, and with the tested parts of gavel exciting, then; Gather tested parts exciting acoustic signals with the sound wave induction pick-up; Acoustic signals converts voltage signal into through sensor, and voltage signal is transferred to the signal acquisition process device after amplifying conditioning through prime amplifier again, and the professional signal analysis software (DHDAS signal testing analytic system software) that passes through again in the computing machine carries out from analysis of spectrum the sound wave digital signal that the signal acquisition process device transmits; So just can test the natural frequency of parts through acoustic signals; Wherein, the concrete operations step of this method is following
At first, tested parts (1) are placed on the workbench (3); Then; Sound wave induction pick-up (4) is placed on the 3cm～5cm place of the tested parts of distance (1); Use the tested parts of gavel exciting (1) again, gather the sound wave that tested part sends through sound wave induction pick-up (4), sound wave passes through prime amplifier (5), signal acquisition process device (6) successively; Finally, export each order frequency of tested parts by computing machine (7).
Wherein, when tested parts are integrated impeller blade, can be with after placing Rubber washer on the disk body of integrated impeller blade; On the disk body Rubber washer, place the counterweight anchor clamps again, and then carry out the exciting test, placing the counterweight anchor clamps on the disk body Rubber washer is for the vibration of damping disk body; Filter out disk body natural frequency acoustic signals like this, simultaneously, also can damping be carried out in the zone that need not in the integrated impeller blade to detect; During testing complex component partial zone natural frequency, consider that vibration could produce sound, tests the regional area natural frequency through the test vibration sound wave; Like this we can take reasonable measure with complex component lose interest in the part vibration damping fall; Do not vibrate and just not produce acoustic signals, we can filter out from just will the lose interest in natural frequency of part of vibration source like this, and preferred damping mode is filling high-absorbable material; Like high-density sponge etc.; Both the disk body coupled vibrations can be prevented through above measure, the vibration coupling of adjacent blades can be placed again, thus the blade natural frequency measurement, degree of accuracy that improves greatly.
In addition; Because blisk complex structure; The traditional shaking table resonant method and the hammering method of touch sensor all can't be measured, and the test advantage of acoustic method just in time can satisfy the natural frequency test of integral blade, and this technological gap has been filled up in the test of the acoustic method of blisk like this.
When tested parts are the engine operation blade, before measuring, need to use corresponding anchor clamps 2 that engine operation blade 1 is fixed on the workbench 3.
The acoustic testing method of a kind of engine component natural frequency provided by the invention requires the test environment noise above blade knock sound pressure level, is preferably quietly carrying out in the laboratory, and simultaneously, during with the gavel exciting, the exciting action will be fast, totally.
Because acoustic signals can be regarded a continuous time dependent sample function X (t) as, its autocorrelation function is:
Autocorrelation function description-individual moment signal and another be the mutual relationship between the signal constantly, is that the quantity of correlativity between two states is described.
Monolateral spectrum certainly is:
Be the statistic
of stationary process x (t), can convert the statistic
of frequency to through Fourier transform in time domain.
The area that
and f axle are surrounded equals the root-mean-square value of x (t); So
is called the mean square power spectral density function again; The energy-structure of its characterization signal; We can find out frequency characteristic and the main frequency composition of signal x (t) by it, so finally can finally obtain the natural frequency of tested parts from the analysis result of computing machine.
By above analysis; We can know that the acoustic method frequency measurement is suitable for the natural frequency test of large and complex structure spare; The required excitation energy of test process is little, particularly the such large-scale component of blisk need not professional anchor clamps, adds the rational vibration damping method of taking; In the integrated impeller blade frequency measurement, reduce coupled vibrations, can obtain desirable test result; In addition, the gavel exciting mode is adopted in the acoustic method frequency measurement, and required exciting force is less, adds that the wooden mallet material is softer, can not cause damage to parts.And taking of signal is the voice signal of gathering parts through non-contacting microphone; Again acoustic signals is carried out former rank natural frequency that analyzing and processing obtains parts; The installation site of sensor is very little to the test result influence; Can fixation of sensor motionless in batch testpieces, one time exciting can obtain the multistage frequency of parts, and the test frequency range broad.
The acoustic testing method of engine component natural frequency provided by the invention has simple to operately, does not injure parts, and test frequency range is wide, the accurate advantage of test result.
Description of drawings
Fig. 1 is the synoptic diagram of acoustical testing system;
Fig. 2 is the synoptic diagram of shaking table test macro;
Fig. 3 is the structural representation of clamp body;
Fig. 4 is the structural representation at gantry;
Fig. 5 is the synoptic diagram of integrated impeller blade after the damping.
Embodiment
Use the frequency of acoustic method test engine high pressure three level work blades, working-blade A is fixed on the workbench with clamp body and gantry, wherein the structure of clamp body sees that the structure at Fig. 3, gantry sees Fig. 4; Then; Microphone MPA401 is placed on the 3cm～5cm place of the tested blade of distance; With the tested blade of gavel exciting; Gather the sound wave that tested part sends through the sound wave induction pick-up, convert acoustic signals into voltage signal through sensor, voltage signal is transferred to signal acquisition process device DH5920 after amplifying through prime amplifier; The sound wave digital signal that through the DHDAS signal testing analytic system software in the computing machine signal acquisition process device is transmitted again carries out obtaining the natural frequency of working-blade from analysis of spectrum.
Test result, see table 1:
Table 1:
| |
1 | 2 | 3 | 4 | 5 |
| Quiet frequency (Hz) | 962.3 | 2755.7 | 3729.2 | 4705.8 | 6689.5 |
Comparative Examples 1
Use the frequency of shaking table resonant method test engine high pressure three level work blade A:
(1) retention system: comprise clamp body and gantry;
When gantry and clamp body are installed, should note following some:
A. anchor clamps and the shaking table rigidity of drawing wants enough big, sometimes because anchor clamps and table top loose contact, connects insecure or anchor clamps and table top rigidity deficiency and influence frequency-measurement accuracy;
B. the rationality of clamp structure, clamping mode, the machining precision of fixture block and wearing and tearing crackle all influence the precision of frequency measurement.
(2) data acquisition and output system: form by lifting the device that shakes (non-contact sensor), amplifier, oscillograph, frequency meter, strainmeter and milivoltmeter etc. usually.Its function is to experience the vibration signal of blade, distinguishes accurately through surveying instrument whether blade resonates, displayed record natural frequency value.
(3) excitation system: form by oscillator (signal generator) power amplifier and vibrator usually.Its function provides exciting force (generally being simple harmonic quantity) for blade, makes it to take place forced vibration to promote blade.
Excitation system should have enough energy, and the power width of cloth and the frequency of exciting force can be regulated (or Automatic Frequency scanning) arbitrarily continuously, and after the setting, it is stable that the power width of cloth and frequency can both keep.Vibrator is divided into contact and contactless, and the DC4-600-2l electromagnetic vibration generator system of contact is adopted in this test.The shaking table test macro connects signal, sees Fig. 1.
In the process of the test, shaking table preheating 20 minutes has just begun to seek the fundamental frequency brief acceleration and has been set to 10m/s
2, adjust the shaking table frequency on this basis from 50Hz to 3000Hz, in order to make blade resonance need suitable increasing shaking table output energy, record engine three grade blade natural frequency values and see table 2 in the time of need looking for high order of frequency:
Table 2:
| |
1 | 2 |
| Quiet frequency (Hz) | 961.8 | 2754.9 |
Because shaking table maximum vibration frequency is 3000Hz, so the shaking table test result can only be tested the blade natural frequency in the 3000Hz scope.
Through test compares and can know with traditional shaking table method test result to acoustic method; The result of two kinds of method of testings is almost consistent; The reliability of acoustic method test has been described, and acoustic method once can obtain the natural frequency in the broad frequency band, generalized case; It really is natural frequency that the blade frequencies that the shaking table resonant method records always is lower than blade itself, can know that through above-mentioned test result the measured blade natural frequency of acoustic method more approaches the real natural frequency value of blade.
Randomly drawing engine rotor blade B, C, D is testpieces, first three rank natural frequency of pilot blade, and concrete test process is following; Spinner blade is fixed on the workbench with clamp body and gantry; Then, microphone is placed on the 3cm～5cm place apart from tested blade, with the tested blade of gavel exciting; Gather the sound wave that tested part sends through the sound wave induction pick-up; Convert acoustic signals into voltage signal through sensor, voltage signal is transferred to the signal acquisition process device after amplifying through prime amplifier, and the sound wave digital signal that through the DHDAS signal testing analytic system software in the computing machine signal acquisition process device is transmitted is again carried out from analysis of spectrum; Obtain the natural frequency of working-blade, test result is seen table 3.
Comparative Examples 2
Use first three rank natural frequency of shaking table resonant method test engine spinner blade B, C, D, concrete test process is following, with the vanes fixed of test on electromagnetic vibration generator system; Carry out exciting then, wherein parts produce forced vibration under the exciting force effect of adjustable frequency; When excitation force frequency equals its natural frequency, amplitude will sharply increase, and this moment, part got into resonance state; The part vibration frequency that under resonance state, records; Be exactly its natural frequency, test macro connects synoptic diagram and sees Fig. 2, and test result is seen table 3.
Table 3
Contrast by test findings in the table 3 can know that the acoustic method test is almost consistent with traditional shaking table method test result, and the reliability of acoustic method test has been described.Generalized case, the blade frequencies that the shaking table resonant method records always are lower than the true natural frequency of blade itself, through above-mentioned test result can know the measured blade natural frequency of acoustic method more near with blade natural frequency value really.
The test of integrated impeller blade natural frequency; Because blisk complex structure; Can't test with classic method, and the test advantage of acoustic method just in time can satisfy the natural frequency test of integral blade, this technological gap has been filled up in the test of the acoustic method of blisk like this.
The principle of its test process is following: at first; With the tested parts of gavel exciting; Then; Gather tested parts exciting acoustic signals with the sound wave induction pick-up, acoustic signals converts voltage signal into through sensor, and voltage signal is transferred to the signal acquisition process device after amplifying conditioning through prime amplifier again; The professional signal analysis software (DHDAS signal testing analytic system software) that passes through again in the computing machine carries out from analysis of spectrum the sound wave digital signal that the signal acquisition process device transmits, and so just can test the natural frequency of parts through acoustic signals.
The concrete operations step is following,
---integrated impeller blade is lain on the workbench;
---used high-density sponge to carry out damping by adjacent about 8 blade of lateral lobe sheet the integrated impeller blade middle distance, see Fig. 5; With professional mass damping disk body vibration;
---microphone is placed on the 3cm～5cm place apart from integrated impeller blade; Then, with the tested blade of gavel exciting, gather the sound wave that tested blade sends through the sound wave induction pick-up; Sound wave passes through prime amplifier, signal acquisition process device successively; Finally, export each order frequencies of tested parts by computing machine, test structure is seen table 4.
Table 4:
| |
1 | 2 | 3 |
| Quiet frequency (Hz) | 808.2 | 2097.6 | 2905.7 |
Claims (7)
1. the acoustic testing method of an engine component natural frequency, it is characterized in that: concrete testing procedure is following,
At first, tested parts (1) are placed on the workbench (3); Then; Sound wave induction pick-up (4) is placed on the 3cm～5cm place of the tested parts of distance (1); Use the tested parts of gavel exciting (1) again, gather the sound wave that tested part sends through sound wave induction pick-up (4), sound wave passes through prime amplifier (5), signal acquisition process device (6) successively; Finally, export each order frequency of tested parts by computing machine (7).
2. according to the acoustic testing method of the said engine component natural frequency of claim 1, it is characterized in that: described engine component is an integrated impeller blade.
3. according to the acoustic testing method of the said engine component natural frequency of claim 1, it is characterized in that: described engine component is the engine operation blade.
4. according to the acoustic testing method of the said engine component natural frequency of claim 2, it is characterized in that: after placing Rubber washer on the disk body of integrated impeller blade, on the disk body Rubber washer, place the counterweight anchor clamps again, carry out the exciting test then.
5. according to the acoustic testing method of the said engine component natural frequency of claim 2, it is characterized in that: damping is carried out in the zone that need not in the integrated impeller blade to detect.
6. according to the acoustic testing method of the said engine component natural frequency of claim 5, it is characterized in that: described damping mode is for filling the high-absorbable material.
7. according to the acoustic testing method of the said engine component natural frequency of claim 3, it is characterized in that: use anchor clamps (2) that engine operation blade (1) is fixed on the workbench (3).
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Cited By (12)
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| CN103196644A (en) * | 2013-04-09 | 2013-07-10 | 中国航空动力机械研究所 | Testing device and testing method of integral-impeller blade vibration fatigue |
| CN104265681A (en) * | 2014-08-01 | 2015-01-07 | 中国人民解放军第五七一九工厂 | Method for changing inherent frequencies of blades |
| CN104501941A (en) * | 2014-12-02 | 2015-04-08 | 苏州长风航空电子有限公司 | Method for testing the low-frequency inherent frequency of aircraft engine sensor |
| CN105701278A (en) * | 2016-01-05 | 2016-06-22 | 东华大学 | Modal parameter acquisition method |
| CN106762592A (en) * | 2016-11-09 | 2017-05-31 | 北京工业大学 | A kind of naval vessel direct-drive type plunger displacement pump resonant frequency method of testing |
| CN106950280A (en) * | 2017-03-16 | 2017-07-14 | 东北大学 | Fibre reinforced composites parameter identification method and device based on the lossless scanning of laser |
| CN108318200A (en) * | 2018-01-10 | 2018-07-24 | 东方电气集团东方汽轮机有限公司 | A kind of Static Leaf vibration frequency test system and its application method |
| CN109278196A (en) * | 2018-11-19 | 2019-01-29 | 湖南高速铁路职业技术学院 | Stonecutter basis Modal detection equipment and detection method |
| CN110631689A (en) * | 2019-08-20 | 2019-12-31 | 人本集团有限公司 | Wheel hub bearing natural frequency testing device |
| CN110836721A (en) * | 2019-11-28 | 2020-02-25 | 中国航发沈阳黎明航空发动机有限责任公司 | Static frequency testing device and method for blades of blisk of aircraft engine |
| CN112254807A (en) * | 2020-10-26 | 2021-01-22 | 北京中科泛华测控技术有限公司 | Engine blade natural frequency testing system |
| CN114674417A (en) * | 2022-02-14 | 2022-06-28 | 华能(浙江)能源开发有限公司玉环分公司 | Method for monitoring natural dynamic frequency of each rotating part of complex shafting |
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| CN103196644A (en) * | 2013-04-09 | 2013-07-10 | 中国航空动力机械研究所 | Testing device and testing method of integral-impeller blade vibration fatigue |
| CN104265681A (en) * | 2014-08-01 | 2015-01-07 | 中国人民解放军第五七一九工厂 | Method for changing inherent frequencies of blades |
| CN104265681B (en) * | 2014-08-01 | 2016-08-31 | 中国人民解放军第五七一九工厂 | The method changing blade self natural frequency |
| CN104501941B (en) * | 2014-12-02 | 2018-04-10 | 苏州长风航空电子有限公司 | The method of testing of aero-engine sensor low frequency intrinsic frequency |
| CN104501941A (en) * | 2014-12-02 | 2015-04-08 | 苏州长风航空电子有限公司 | Method for testing the low-frequency inherent frequency of aircraft engine sensor |
| CN105701278A (en) * | 2016-01-05 | 2016-06-22 | 东华大学 | Modal parameter acquisition method |
| CN106762592A (en) * | 2016-11-09 | 2017-05-31 | 北京工业大学 | A kind of naval vessel direct-drive type plunger displacement pump resonant frequency method of testing |
| CN106950280A (en) * | 2017-03-16 | 2017-07-14 | 东北大学 | Fibre reinforced composites parameter identification method and device based on the lossless scanning of laser |
| CN106950280B (en) * | 2017-03-16 | 2019-04-12 | 东北大学 | Fibre reinforced composites parameter identification method based on the lossless scanning of laser |
| CN108318200A (en) * | 2018-01-10 | 2018-07-24 | 东方电气集团东方汽轮机有限公司 | A kind of Static Leaf vibration frequency test system and its application method |
| CN109278196A (en) * | 2018-11-19 | 2019-01-29 | 湖南高速铁路职业技术学院 | Stonecutter basis Modal detection equipment and detection method |
| CN110631689A (en) * | 2019-08-20 | 2019-12-31 | 人本集团有限公司 | Wheel hub bearing natural frequency testing device |
| CN110836721A (en) * | 2019-11-28 | 2020-02-25 | 中国航发沈阳黎明航空发动机有限责任公司 | Static frequency testing device and method for blades of blisk of aircraft engine |
| CN112254807A (en) * | 2020-10-26 | 2021-01-22 | 北京中科泛华测控技术有限公司 | Engine blade natural frequency testing system |
| CN114674417A (en) * | 2022-02-14 | 2022-06-28 | 华能(浙江)能源开发有限公司玉环分公司 | Method for monitoring natural dynamic frequency of each rotating part of complex shafting |
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Application publication date: 20120704 |