CN103592369A - In-situ crack testing method for disk parts of aero-engine - Google Patents

Abstract

The invention discloses an in-situ crack testing method for disk parts of an aero-engine. The in-situ crack testing method comprises the following steps: (1), arranging a plurality of measuring points on the disk parts of the aero-engine, and carrying out the standard modal shape testing to obtain data sequences of modal shapes of first four orders and form corresponding curves of modal shapes of different orders; (2), calculating general local entropies of modal shape data points di on the curves of the modal shapes of different orders to obtain general local entropy crack index curves of the modal shapes of different orders; (3), judging whether cracks exist at the measuring points corresponding to the maximum peak or not according to the relations among the maximum peak, the minimum peak and the secondary maximum peak of the general local entropy crack index curves of the modal shapes of different orders. The in-situ crack testing method has high in-situ performance, and is convenient for site instruction of in-situ dynamic nondestructive testing of the disk parts such as a turbine disk of the aero-engine.

Description

A kind of aeromotor disk-like accessory crack detecting method in place

Technical field

The present invention relates to Structural Dynamics Dynamic Non-Destruction Measurement, be specifically related to a kind of aeromotor disk-like accessory crack detecting method in place.

Background technology

The characteristic of aeromotor is the deciding factor of performance, reliability and the cost of aircraft, and its lifetime expense accounts for the 20%-40% of whole aircraft.Moreover, because aeromotor cost is high, any technical small improvement all can cause great economic benefit, so the status monitoring of aircraft engine and Fault Quick Diagnosis are important and difficult research directions.

Nearly ten years, Europe is under the promotion and subsidy of European Union's the 6th scientific and technological framework planning and the 7th scientific and technological framework planning, successively investment surpasses 100,000,000,000 Euros and carries out science and technology innovation, in order to improve the reliability of aircraft and a plurality of research centres that the security ，Yi EASA of EASA is core, carry out one after another the investigation of Liao Dui EASA member state military and civilian aircraft culprit and treating method.Compare western developed country, aircraft industry is the short slab of China, particularly aeromotor life problems.The J-79 of the General Corporation engine using with meter Ge-21 U.S. of the same period F-4 fighter plane, its life-cycle can reach about 4000 hours, and some advanced aircrafts, as F-110 and the F-136 engine that F-15, F-22 were used, its life-cycle has reached respectively 6000-8000 and more than 13000 hours especially.By contrast, China's military secret engine life-cycle generally about 1000-2000 hour, and relies on foreign import to a certain extent.

For these problems, China is to improve operational reliability at the national economy and social development 11th Five-Year Plan outline > > of the < < People's Republic of China (PRC) by great product and great installation forecasting technique in life span, security, maintainability is classified gordian technique research as, in < < ' 12 ' outline > >, also clearly emphasized " the detection of Important Project health status, monitoring and diagnosis and dispose " importance of research.The disk-like accessories such as the turbine disk, as the core component of aeromotor, have material impact to engine life, therefore carry out aeromotor disk-like accessory monitoring structural health conditions in place and are significant.

Summary of the invention

The object of the present invention is to provide a kind of aeromotor disk-like accessory crack detecting method in place, the crackle of the disk-like accessories such as aero-engine turbine disk is carried out to dynamics nondestructive examination.

For realizing above goal of the invention, technical scheme of the present invention is as follows:

A disk-like accessory crack detecting method in place, comprises the following steps:

(1) a plurality of measuring points are set on aeromotor disk-like accessory, carry out normal modal test, obtain front quadravalence Mode Shape data sequence, and form each corresponding rank Mode Shape curve;

(2) calculate each Mode Shape data point d on each rank Mode Shape curve _ibroad sense local entropy (GLE), obtain the broad sense local entropy crackle indicative curve of each rank Mode Shape;

(3), according to the relation of peak-peak, minimum peak and inferior peak value on the broad sense local entropy crackle indicative curve of each rank Mode Shape, judge whether measuring point place corresponding to this peak-peak occurs crackle.

Technique effect of the present invention is:

1) take information entropy theory as basis, formed a kind of without the dynamics lossless detection method as a reference of data under structural health conditions;

2) utilize broad sense local entropy peak value can clearly judge damage position;

3) computing of the present invention property in place is good, simple, is convenient to the dynamics Non-Destructive Testing in place of the disk-like accessories such as on-the-spot guidance aero-engine turbine disk.

Accompanying drawing explanation

Fig. 1 is experiment test scheme schematic diagram;

Fig. 2 is for to arrange schematic diagram at bit test measuring point;

Fig. 3 is measuring point 3 test datas;

Fig. 4 is full measuring point 200-2500Hz frequency range frequency response function;

Fig. 5 is front quadravalence Mode Shape GLE crackle indicative curve.

Embodiment

Below in conjunction with accompanying drawing, content of the present invention is described in further detail:

The aeromotor disk-like accessory crack detecting method in place that the present invention proposes, comprises the following steps:

(1) a plurality of measuring points are set on aeromotor disk-like accessory, carry out normal modal test, obtain front quadravalence Mode Shape data sequence, and form each corresponding rank Mode Shape curve.

Wherein, normal modal test can employing power be hammered tap test, resonant method survey mode etc. into shape.In this specific embodiment, the hammering mode test macro that test macro is standard, as shown in Figure 1.Experimental configuration comprises one, universal portable computer, domestic Econ AVANT MI-7008 data collecting instrument is a set of, and domestic Dong Huali hammer and each of PCB-300A12 type single-axis acceleration sensors, Validity Test frequency field 10-10000Hz, for obtaining as far as possible many information, sample frequency is set to 10240Hz, so analysis frequency is about below 4000Hz, and selected sensor decay can meet test analysis requirement.

With reference to Fig. 2, at bit test measuring point, schematic diagram is set.It may be noted that this specific embodiment take turbine disk body as example, but it will be appreciated by those skilled in the art that other disk-like accessories for aeromotor, the present invention is applicable too.At turbine disk body, each tongue-and-groove place respectively arranges a measuring point, in this specific embodiment, take 47 tongue-and-grooves as indexed configuration measuring point, make one by one firmly hammer carry out mode test with acceleration transducer: with power hammer, to knock downside disk body, sensor is arranged in upside disk body, now power hammer hammer force will be passed to sensor by the multiple position of crackle, with this, obtain the quadravalence vibration shape before turbine disk body.After this measuring point has been tested, move to next measuring point and test.Each measuring point knocks firmly hammer 10 times, does linear averaging to reduce noise effect.The signal collecting is power hammer pumping signal time series and as response signal seasonal effect in time series acceleration signal.Fig. 3 (a) and Fig. 3 (b) are respectively pumping signal time series and the response signal time series of measuring point 3.By Fig. 3 (a) is done to ratio with the inputoutput data shown in Fig. 3 (b), can obtain the frequency response function of structure, as shown in Fig. 3 (c).

Can see, in analyzed frequency range, co-exist in quadravalence Mode Shape, respectively 1-47 measuring point be extracted to its 1-4 rank Mode Shape peak value, can obtain its Mode Shape curve.Wherein, whole frequency response function corresponding peaks of measuring point 1-47 are connected, obtain the quadravalence Mode Shape curve shown in Fig. 4.

(2) calculate each Mode Shape data point d on each rank Mode Shape curve _ibroad sense local entropy (GLE), obtain the broad sense local entropy crackle indicative curve of each rank Mode Shape.

Wherein, the definition of described broad sense local entropy and to obtain the detailed process of broad sense local entropy crackle indicative curve as follows:

A) in the concept of entropy, the probability of happening p of definition subevent i _iby this vibration shape amplitude and consecutive point amplitude with assess, be formulated as:

$p_i=\frac{d_i}{\underset{j=i-1}{\overset{i+1}{\mathrm{\&Sigma;}}}{d}_j}---\left(1\right)$

D in formula _irepresent measuring point i vibration shape amplitude, utilize P=(p ₀, p ₁..., p _n) represent the limited discrete probability distribution system that single-degree-of-freedom number is n, according to property of probability, obtain the probability of happening p of each subevent _i>=0 (i=0,1 ..., n), and have

i.e. all subevents probability and be 1.In the concept of entropy, probable value p _ithe entropy that is called as P distributes, entropy H (P) and p _ibetween pass be:

$H\left(P\right)=-\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}{p}_i{\log }_2{p}_i---\left(2\right)$

To after above formula normalization, obtain:

$H\left(P\right)=-\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}\frac{p_i{\log }_2{p}_i}{{\log }_2(n+1)}---\left(3\right)$

In the definition of local entropy, entropy function H is limited in the subsystem L of system P, and to event i, broad sense local entropy is expressed as:

$H\left(P_{\mathrm{Li}}\right)=-\frac{p_i{\log }_2{p}_i}{{\log }_2(N+1)}---\left(4\right)$

Wherein N represents the data length of subsystem L.Thereby can obtain the broad sense local entropy expression formula for structural crack location:

$H\left(P_{\mathrm{Li}}\right)=-\frac{d_i({\log }_2{d}_i-{\mathrm{<figure-callout\; id="2"\; label="log"\; filenames="HDA0000414030120000012.png,HDA0000414030120000031.png"\; state="\{\{state\}\}">log</figure-callout>}}_2\underset{j=0}{\overset{N}{\mathrm{\&Sigma;}}}{d}_j)}{\underset{j=0}{\overset{N}{\mathrm{\&Sigma;}}}{d}_j{\log }_2(N+1)}---\left(5\right)$

D in formula _ithe vibration shape amplitude that represents measuring point i, d _jthe vibration shape amplitude that represents measuring point j adjacent with measuring point i in standard window, N is standard window length.

Consider two measuring point impacts that measuring point left and right is adjacent, choose N=3 long as standard window, if need, consider four measuring point impacts that measuring point left and right is adjacent, choose N=5 long as standard window, by that analogy.N value can effectively suppress to measure noise greatly, but larger N value chooses and can cause in mode test experiments measuring point number to become many, should choose as the case may be, and in the present embodiment, it is long as standard window that N=3 is chosen in suggestion, to reduce the measuring point data of needs.

B) Mode Shape data point d normal modal test being obtained _idifference substitution broad sense local entropy calculating formula (5), horizontal ordinate is measuring point numbering, ordinate is the local entropy of broad sense, obtains broad sense local entropy crackle indicative curve.Figure 5 shows that the broad sense local entropy crackle indicative curve of front quadravalence Mode Shape.

(3), according to the relation of peak-peak, minimum peak and inferior peak value on the broad sense local entropy crackle indicative curve of each rank Mode Shape, judge whether measuring point place corresponding to this peak-peak occurs crackle.

Particularly, this decision criteria can be expressed as: if the peak-peak of broad sense local entropy crackle indicative curve and its minimum peak difference are time peak value and the more than 1.2 times of minimum peak difference, think that measuring point place corresponding to this peak-peak place is candidate's crack position.Wherein, because low order mode in mode test is more accurate, in the broad sense local entropy crackle indicative curve of front quadravalence Mode Shape, if single order or second order meet above-mentioned decision criteria, judge that this measuring point place exists crackle, iff three rank or quadravalence meet, only using this measuring point as object of suspicion.

In Fig. 5, peak-peak and minimum peak be poor has all surpassed inferior peak and poor 1.2 times of minimum peak, therefore think that measuring point 4 and measuring point 27 places may exist crackle, but considering in quadravalence Mode Shape only has the 3rd rank Mode Shape result to provide crackle indication to measuring point 27, and one, two and quadravalence Mode Shape all measuring point 4 is provided to crackle indication, therefore assert that measuring point 4 exists crackle, and measuring point 27 is listed in object of suspicion.By Non-Destructive Testing, find really to have crackle at measuring point 4 places, conform to testing result of the present invention.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.

Claims (4)

1. an aeromotor disk-like accessory crack detecting method in place, comprises the following steps:

(1) a plurality of measuring points are set on aeromotor disk-like accessory, carry out normal modal test, obtain front quadravalence Mode Shape data sequence, and form each corresponding rank Mode Shape curve;

(2) calculate each Mode Shape data point d on each rank Mode Shape curve _ibroad sense local entropy (GLE), obtain the broad sense local entropy crackle indicative curve of each rank Mode Shape;

(3), according to the relation of peak-peak, minimum peak and inferior peak value on the broad sense local entropy crackle indicative curve of each rank Mode Shape, judge whether measuring point place corresponding to this peak-peak occurs crackle.

2. method according to claim 1, wherein, described normal modal test comprises that employing power hammer tap test or resonant method survey mode etc.

3. method according to claim 1, wherein, described step (2) is specially:

(a) the broad sense local entropy calculating formula for structural crack location is:

$H\left(P_{\mathrm{Li}}\right)=-\frac{d_i({\log }_2{d}_i-{\log }_2\underset{j=0}{\overset{N}{\mathrm{\&Sigma;}}}{d}_j)}{\underset{j=0}{\overset{N}{\mathrm{\&Sigma;}}}{d}_j{\log }_2(N+1)}---\left(5\right)$

D in formula _ithe vibration shape amplitude that represents measuring point i, d _jthe vibration shape amplitude that represents measuring point j adjacent with measuring point i in standard window, N is standard window length;

(b) front quadravalence Mode Shape data point d normal modal test being obtained _isubstitution broad sense local entropy calculating formula (5), is numbered horizontal ordinate with measuring point respectively, and the local entropy of the broad sense of take is ordinate, obtains the broad sense local entropy crackle indicative curve of each rank Mode Shape.

4. method according to claim 1, wherein, in described step (3), decision criteria is: if the peak-peak of broad sense local entropy crackle indicative curve and its minimum peak difference are time peak value and the more than 1.2 times of minimum peak difference, think that measuring point place corresponding to this peak-peak place is candidate's crack position, wherein, for the broad sense local entropy crackle indicative curve of front quadravalence Mode Shape, if single order or second order meet above-mentioned decision criteria, judge that this measuring point place exists crackle; Iff three rank or quadravalence meet, only using this measuring point as object of suspicion.

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