CN103592369B - A kind of disc part of aero-engine crack detecting method in place - Google Patents

Abstract

The invention discloses a kind of disc part of aero-engine crack detecting method in place, comprise the following steps: (1) arranges multiple measuring point in disc part of aero-engine, carry out normal modal test, obtain front quadravalence Mode Shape data sequence, and form corresponding each rank Mode Shape curve; (2) each Mode Shape data point d on the Mode Shape curve of each rank is calculated _ibroad sense local entropy, 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 secondary 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.Computing of the present invention property in place is good, 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.

Description

A kind of disc part of aero-engine 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 disc part of aero-engine crack detecting method in place.

Background technology

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

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

For these problems, China " People's Republic of China's national economy and social development 11th Five-Year Plan outline " by great product and great installation forecasting technique in life span be improve operational reliability, security, maintainability be classified as gordian technique research, also clearly highlights the importance that " detection of Important Project health status, monitoring and diagnosis and disposal " is studied in " ' 12 ' outline ".The disk-like accessories such as the turbine disk, as the core component of aeromotor, have material impact to engine life, therefore carry out disc part of aero-engine 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 disc part of aero-engine crack detecting method in place, dynamics nondestructive examination is carried out to the crackle of the disk-like accessories such as aero-engine turbine disk.

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

A kind of disc part of aero-engine crack detecting method in place, comprises the following steps:

(1) multiple measuring point is set in disc part of aero-engine, carries out normal modal test, obtain front quadravalence Mode Shape data sequence, and form corresponding each rank Mode Shape curve;

(2) each Mode Shape data point d on the Mode Shape curve of each rank is calculated _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 secondary 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) based on information entropy theory, define a kind of without the need to the dynamics lossless detection method as a reference of data under structural health conditions;

2) broad sense local entropy peak value is utilized clearly can to 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 arrange schematic diagram at bit test measuring point;

Fig. 3 is measuring point 3 test data;

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 disc part of aero-engine crack detecting method in place that the present invention proposes, comprises the following steps:

(1) multiple measuring point is set in disc part of aero-engine, carries out normal modal test, obtain front quadravalence Mode Shape data sequence, and form corresponding each rank Mode Shape curve.

Wherein, normal modal test can adopt power to hammer tap test into shape, resonant method surveys mode etc.In this specific embodiment, test macro is the hammering mould measurement system of standard, as shown in Figure 1.Experimental configuration comprises one, universal portable computer, domestic EconAVANTMI-7008 data collecting instrument is a set of, and domestic Dong Huali hammers into shape and each one 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, and therefore analysis frequency is about below 4000Hz, and selected sensor decay can meet test analysis requirement.

With reference to Fig. 2, schematic diagram is set at bit test measuring point.It may be noted that this specific embodiment is for turbine disk body, but it will be appreciated by those skilled in the art that other disk-like accessories for aeromotor, the present invention is suitable for too.At turbine disk body, each tongue-and-groove place respectively arranges a measuring point, in this specific embodiment, with 47 tongue-and-grooves for indexed configuration measuring point, firmly hammer and acceleration transducer is made to carry out mould measurement one by one: to hammer into shape with power and 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, obtain four first order modes before turbine disk body with this.After this measuring point has been tested, move to next measuring point and tested.Each measuring point makes firmly hammer knock 10 times, does linear averaging to reduce noise effect.The signal collected is the acceleration signal of power hammer pumping signal time series and responsively signal time sequence.Fig. 3 (a) and Fig. 3 (b) are respectively pumping signal time series and the response signal time series of measuring point 3.By doing ratio to the inputoutput data shown in Fig. 3 (a) Yu Fig. 3 (b), the frequency response function of structure can be obtained, as shown in Fig. 3 (c).

Can see, in analyzed frequency range, co-exist in quadravalence Mode Shape, respectively its 1-4 rank Mode Shape peak value be extracted to 1-47 measuring point, its Mode Shape curve can be obtained.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) each Mode Shape data point d on the Mode Shape curve of each rank is calculated _ibroad sense local entropy (GLE), obtain the broad sense local entropy crackle indicative curve of each rank Mode Shape.

Wherein, described broad sense local entropy definition 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:

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

D in formula _irepresent measuring point i vibration shape amplitude, utilize P=(p ₀, p ₁..., p _n) represent that single-degree-of-freedom number is the probability distribution system of the finite discrete of n, the probability of happening p of each subevent is obtained according to property of probability _i>=0 (i=0,1 ..., n), and have i.e. all subevents probability and be 1.In the concept of entropy, probable value p _ibe called as the entropy distribution of P, entropy H (P) and p _ibetween pass be:

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

Obtain after above formula normalization:

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

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.Thus the broad sense local entropy expression formula that can obtain for structural crack location:

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

D in formula _irepresent the vibration shape amplitude of measuring point i, d _jrepresent the vibration shape amplitude of 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, then choose N=3 long as standard window, if four measuring point impacts that measuring point left and right is adjacent need be considered, then choose N=5 long as standard window, by that analogy.N value effectively can suppress measurement noises greatly, but larger N value choose mould measurement can be caused to test in measuring point number become many, should choose as the case may be, in the present embodiment, to choose N=3 long as standard window in suggestion, to reduce the measuring point data of needs.

B) normal modal is tested the Mode Shape data point d obtained _isubstitute into broad sense local entropy calculating formula (5) respectively, horizontal ordinate is measuring point numbering, and ordinate is broad sense local entropy, namely 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 secondary 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.

Specifically, 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 more than 1.2 times of minimum peak difference, then think that measuring point place corresponding to this peak-peak place is candidate's crack position.Wherein, because low order mode in mould measurement 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, then judge that this measuring point place exists crackle, meet iff three rank or quadravalence, then only using this measuring point as object of suspicion.

In Fig. 5, peak-peak and minimum peak difference have all exceeded 1.2 times of secondary peak and minimum peak difference, therefore think that measuring point 4 and measuring point 27 place may exist crackle, but consider in quadravalence Mode Shape and only have the 3rd rank Mode Shape result to provide crackle instruction to measuring point 27, and one, two and quadravalence Mode Shape all to measuring point 4 provide crackle instruction, therefore assert that measuring point 4 exists crackle, and measuring point 27 is listed in object of suspicion.Find really there is crackle at measuring point 4 place by Non-Destructive Testing, 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 amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. a disc part of aero-engine crack detecting method in place, comprises the following steps:

(1) multiple measuring point is set in disc part of aero-engine, carries out normal modal test, obtain front quadravalence Mode Shape data sequence, and form corresponding each rank Mode Shape curve;

(2) each Mode Shape amplitude d on the Mode Shape curve of each rank is calculated _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 secondary 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 employing power hammer tap test or resonant method surveys mode.

3. 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 more than 1.2 times of time peak value and minimum peak difference, then think that measuring point place corresponding to this peak-peak place is for 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, then judge that this measuring point place exists crackle; Meet iff three rank or quadravalence, then only using this measuring point as object of suspicion.