CN105866250A - Vibration-based identification method for cracks of ventilating vane - Google Patents

Abstract

The invention provides a vibration-based identification method for cracks of a ventilating vane, belonging to the field of fault diagnosis of equipment. The method comprises the following steps: measuring the overall response of the vibration of the vane at first and determining the position and size of a crack, wherein the position of the crack is determined at first and then the size of the crack is determined; determining positional parameters of the crack according to the overall response; and decomposing the overall response into two local responses after determination of the position of the crack and determining the severity of the crack according to a difference value between the inherent frequencies of the local responses, i.e., according to relative variation of the local responses, wherein a crack fault does not exist if the two frequencies are equal, the crack exists if the two frequencies are not identical, the crack is severe if the relative variance is great, and the crack is small if the relative variance is small. According to the invention, a similarity criteria is established to measure the position of a damage; and compared with the prior art, the identification method provided by the invention is simple, fast, reliable and easily practicable.

Description

Ventilating vane method for crack based on vibration

Technical field

The present invention relates to the recognition methods of a kind of ventilating vane crackle.Specifically, the invention relates to ventilating vane Crack position and the recognition methods of crackle size, belong to field of diagnosis about equipment fault.

Background technology

Ventilation blower is the machinery that a kind of rotary shaft equipped with several blades promotes air-flow.Motor is put on the rotation on axle by blade Mechanical energy is the pressure promoting gas flowing, thus realizes the flowing of gas.It is the vitals of fan rotor system.

For ventilating vane, due in the defect cast, weld, design, it is easy to cause blade stress to be concentrated；It is bullied Time, geographical position and the restriction of economic aspect, it is impossible to the material that enough only consideration hardness is high, fatigue resistance is strong；Secondly in rotor system During system work, blade can be pneumatic by the centrifugal force produced during displacement and stable state and astable air-flow power effect Interaction between power and mechanical oscillation causes blade to vibrate, and unsteady motion occurs.Blade vibration is bigger by producing Dynamic stress, causes the fatigue of blade, cracks and even rupture.Additionally, due to blade subjects from the temperature difference and medium etc. Comprehensive function, also make blade be easy to occur mechanical breakdown.Blower fan unit operation is constituted safely the biggest by the generation of crackle Threaten, even result in the generation of major accident, also produce to enterprise and bring great economic loss.

Carry out the research of Identification of Cracks problem based on structural vibration and system dynamic parameter although a lot of method is had been developed traditional, But due to Practical Project complexity and uncertainty (such as impact of the high intensity noise at scene, dust etc.) so that these Method has difficulties in actual application aspect.All there is limitation (many counting methods can realize determining crackle in these methods simultaneously Exist, but position and the size of crackle can not be determined simultaneously).So, it is badly in need of proposing one and there is non-destructive, quick, honest and clean Valency and the new method of non-destructive tests based on structural vibration being easily achieved.

Summary of the invention

The present invention can realize the Blade Crack Fault quickly recognizing ventilating vane of degree of precision, including the position of crackle and big Small parameter.

For achieving the above object, the present invention adopts the following technical scheme that.Concrete implementation step is as described below:

First, measuring the overall situation response of blade vibration, this response is dynamic respond or acceleration responsive.Because blade mostly is high Frequency vibration, so in most cases record is acceleration responsive curve.The position of crackle and the determination of size, it is first determined split The position of line, it is then determined that the size of crackle.

Utilize the overall situation that obtains in response to determining that the location parameter of crackle.Structure frequency has easily to be measured and that data are more accurate is excellent Gesture, so the present invention carries out non-destructive tests based on frequency.After obtaining overall situation response, measure former rank (of good blade As choose front 6 rank) intrinsic frequency carry out record, then measure fault blade in the case of the different crack position parameter of many groups Intrinsic frequency record, the characteristic pattern of the intrinsic frequency squared frequency test showed in the presence of setting up crackle (that is set up one Damage storehouse).The value obtained finally by actual experiment and damage database data compare, it is judged that the position that crackle occurs.Frequency is put down Fang Bianhua, than the method for damage reason location, can only substantially judge damage position, the most but with the biggest randomness from figure.Right In same figure, different observers possibly even draws antipodal conclusion, one standard of the most necessary proposition. Formulate a similarity criterion, quantify crackle by this index value and the possibility in this position occurs.By actually measured value with Damage database data compares, and the data that compared result obtains are analyzed, and determines the particular location letter of crackle more accurately Breath.

Before identifying crack position information, need to set up a standard similarity criterion.Frequency square change is more similar than vector Degree criterion index can be obtained by following formula:

$AC(F_1,F_2)=\frac{{\left(F_1^T{F}_2\right)}^2}{\left(F_1^T{F}_1\right)\left(F_2^T{F}_2\right)}$

F in formula₁,F₂Represent the frequency square change ratio that the frequency square change in damage storehouse obtains than vector sum field experiment respectively Vector, intrinsic frequency change duplicate ratio vector correlation criterion represents two vectorial degrees of correlation, if value is 0, this feelings is described Not causing the change of frequency under condition, blade is intact, if close to 1, illustrates that this degree of impairment causes the change of frequency, Thus may determine that damage position, after having had this related criteria, directly quantify similarity degree by the size of numerical value；Phase The biggest like degree, illustrate that crackle occurs the possibility in this position the biggest, when similarity degree is more than 90% when, it is possible to really Recognize crack fault just to occur in this position.

After determining crack position, overall situation response is decomposed into Liang Ge local acknowledgement, determines the size parameter of crackle with this. The rigidity of blade can change at equilbrium position (x=0) place of system.And the existence of crackle so that time blade is intact Rigidity k changes, and the rigidity that the crackle left side is one section becomes k₁, the rigidity that the right is one section becomes k₂.Specifically, according to displacement X>=0 and displacement x<0 or according to acceleration a≤0 and a ＞ 0, Liang Ge local acknowledgement is resolved in overall situation response.Further, MATLAB software programming is utilized to obtain the spectrogram of each local acknowledgement, it is thus achieved that locally natural frequency value ω₁And ω₂.Then will The difference of two frequencies obtained contrasts, so that it is determined that the order of severity of crackle.

Relative variation according to the difference of local acknowledgement's intrinsic frequency, i.e. intrinsic frequency identifies the order of severity of crackle:

${\mathrm{\&Delta;\&omega;}}_{1,2}=\frac{{\mathrm{\&omega;}}_2-{\mathrm{\&omega;}}_1}{{\mathrm{\&omega;}}_1}\left(\%\right)$

If two frequency values are equal, illustrate that blade does not exist crack fault；If two frequency values differ in size, blade is described Crackle exists；And if relative variation is bigger, then illustrate that the crackle ratio produced is more serious；Otherwise what then explanation produced splits Line is less.

By above step, just complete the determination of blade cracks position and size information.

The crack position of identification blade of the present invention and size, have a following distinguishing feature:

1, the identification process to the severe crack degree of blade, it is not necessary to the Data Comparison of repetitive measurement, but simply use same Secondary measurement data.Thus be no longer necessary to reference data, can avoid the interference of extraneous various factors simultaneously, by extraneous because of Element change and the impact of measure error；

2, being obtained intrinsic frequency by local acknowledgement, the change of its value has higher sensitivity；

3, frequency square change is than the method for damage reason location, if none of standard, just can only substantially judge damage from figure Position, intuitively with the biggest randomness.So, the present invention establishes a similarity criterion and weighs the position that damage occurs；

4 and other existing methods contrast, the method for identification crackle of the present invention is simple, quick, reliable, easy.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or prior art In description, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only the one of the present invention A little embodiments, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to according to these Accompanying drawing obtains other accompanying drawing.

Fig. 1 fan blade crack position and size identification flow chart

Fig. 2 experimental data and the similitude of data in damage storehouse

Fig. 3 blade vibration overall situation responds

Fig. 4 blade vibration local acknowledgement (x > 0)

Fig. 5 blade vibration local acknowledgement (x < 0)

The spectrogram of Fig. 6 local acknowledgement

Detailed description of the invention

With embodiment, the present invention is described in further detail below in conjunction with the accompanying drawings.Following example are used for illustrating the present invention, but not Can be used for limiting the scope of the present invention.

Fig. 1 is fan blade crack position and size identification flow chart.The enforcement step of this method is as follows:

First, measuring the overall situation response of blade vibration, this response can be the dynamic respond obtained by displacement transducer, or The acceleration responsive obtained by acceleration transducer.Because blade mostly is dither, so in most cases record is to accelerate Degree response curve.Dynamic respond curve is used the when of theory analysis.

On the one hand, according to the overall situation response of the blade vibration recorded, the location parameter of crackle is determined.The former rank choosing blade are solid There is frequency (typically choosing front 6 rank), measure any of good blade and the fault blades organized under different Crack Parameters size cases more The size (note: the exponent number of selected intrinsic frequency is identical) of second order intrinsic frequency.Calculate appointing of this selected several rank intrinsic frequency The ratio of the frequency square changing value of two orders of meaning, the feature of the intrinsic frequency showed in the presence of setting up crackle change duplicate ratio Figure (that is setting up a damage storehouse).By formulating similarity criterion index, quantify similarity degree (as shown in Figure 2), directly Describe crackle by the size of numerical value and the possibility in this position occurs.Frequency square change can than vector similarity criterion index To be obtained by following formula:

$AC(F_1,F_2)=\frac{{\left(F_1^T{F}_2\right)}^2}{\left(F_1^T{F}_1\right)\left(F_2^T{F}_2\right)}$

F in formula₁,F₂Represent the frequency square change ratio that the frequency square change in damage storehouse obtains than vector sum field experiment respectively Vector.Intrinsic frequency change duplicate ratio vector correlation criterion represents two vectorial degrees of correlation.This index is in the range of 0-1.If Being 0 change illustrating the most not cause frequency, blade is intact.If close to 1, this degree of impairment is described Cause the change of frequency, structure frequency change duplicate ratio and the data in damage storehouse in the presence of the crackle therefore obtained by experiment Compare, determine the place, position of crackle.By procedure described above, just it has been determined that got well the position of crackle.

On the other hand, according to the overall situation response of the blade vibration recorded, then the size of crackle is determined.Respond above by the overall situation After the crack position information of blade, according to displacement x>=0 and displacement x<0 or according to acceleration a≤0 and a ＞ 0, will Liang Ge local acknowledgement is resolved in overall situation response, determines the size parameter of crackle according to this.MATLAB software programming is utilized to obtain often The spectrogram of individual local acknowledgement, it is thus achieved that locally natural frequency value ω₁And ω₂.Specifically, the blade vibration overall situation as shown in Figure 3 Liang Ge local acknowledgement (as shown in Figure 4 and Figure 5) is resolved in response.The waveform of two parts up and down obtained is reconstructed, will Waveform after reconstruct carries out spectrum analysis, it is possible to obtain the natural frequency ω of regional area₁And ω₂(as shown in Figure 6).By Following formula calculate local intrinsic frequency relative variation:

${\mathrm{\&Delta;\&omega;}}_{1,2}=\frac{{\mathrm{\&omega;}}_2-{\mathrm{\&omega;}}_1}{{\mathrm{\&omega;}}_1}\left(\%\right)$

Utilize Δ ω_1,2This parameter, determines the crackle size information of blade according to the difference of two frequency values.

By procedure described above, just it has been determined that got well crack position and the size information of ventilating vane.

Further, the difference of the sensitivity of the present invention and traditional additive method is contrasted.Before cracking, it is assumed that complete Office's intrinsic frequency size is ω₀, locally intrinsic frequency (during x > 0) ω₁=ω, locally intrinsic frequency (x < when 0) ω₂=ω.This Time, overall situation natural frequency value is:

${\mathrm{\&omega;}}_0=\frac{2{\mathrm{\&omega;}}_1{\mathrm{\&omega;}}_2}{{\mathrm{\&omega;}}_1+{\mathrm{\&omega;}}_2}=\mathrm{\&omega;}$

After having crackle to produce, it is assumed that global frequencies drops to β ω, local frequencies ω₁Drop to α ω (0 < α < 1), local frequency Rate ω₂Keep constant.So, global frequencies can be expressed from the next:

$\mathrm{\&beta;}\mathrm{\&omega;}=\frac{2\mathrm{\&alpha;}\mathrm{\&omega;}\mathrm{\&omega;}}{\mathrm{\&alpha;}\mathrm{\&omega;}+\mathrm{\&omega;}}=\frac{2\mathrm{\&alpha;}\mathrm{\&omega;}}{1+\mathrm{\&alpha;}}$

Being changed to of global frequencies:

${\mathrm{\&Delta;\&omega;}}_0=(1-\mathrm{\&beta;})\mathrm{\&omega;}=\frac{1-\mathrm{\&alpha;}}{1+\mathrm{\&alpha;}}\mathrm{\&omega;}$

The difference of local frequencies is:

Δ ω=(1-α) ω ＞ Δ ω₀

So identifying that severe crack degree is more much higher than based on global frequencies sensitivity based on local frequencies difference.

Claims (2)

1. ventilating vane method for crack based on vibration, it is characterised in that:

Concrete implementation step is as described below,

First, measuring the overall situation response of blade vibration, this response is dynamic respond or acceleration responsive；Because blade mostly is high Frequency vibration, so in most cases record is acceleration responsive curve；The position of crackle and the determination of size, it is first determined split The position of line, it is then determined that the size of crackle；

Utilize the overall situation that obtains in response to determining that the location parameter of crackle；Structure frequency has easily to be measured and that data are more accurate is excellent Gesture, so this method carries out non-destructive tests based on frequency；After obtaining overall situation response, the former rank measuring good blade are intrinsic Frequency also carries out record, the intrinsic frequency of the fault blade in the case of then different crack position parameter is organized in measurement more record, builds The characteristic pattern of the intrinsic frequency squared frequency test showed in the presence of vertical crackle that is set up a damage storehouse；Finally by reality Value and damage database data that experiment obtains compare, it is judged that the position that crackle occurs；Frequency square change is than the side of damage reason location Method, can only substantially judge damage position, the most but with the biggest randomness from figure；For same figure, different Observer possibly even draws antipodal conclusion, one standard of the most necessary proposition；Formulate a similarity criterion, Quantify crackle by this index value and the possibility in this position occurs；Actually measured value is compared with damage database data, The data that compared result obtains are analyzed, and determine the more specific location information of crackle more accurately；

Before identifying crack position information, need to set up a standard similarity criterion；Frequency square change is more similar than vector Degree criterion index can be obtained by following formula:

$AC(F_1,F_2)=\frac{{\left(F_1^T{F}_2\right)}^2}{\left(F_1^T{F}_1\right)\left(F_2^T{F}_2\right)}$

F in formula₁,F₂Represent the frequency square change ratio that the frequency square change in damage storehouse obtains than vector sum field experiment respectively Vector, intrinsic frequency change duplicate ratio vector correlation criterion represents two vectorial degrees of correlation, if value is 0, this feelings is described Not causing the change of frequency under condition, blade is intact, if close to 1, illustrates that this degree of impairment causes the change of frequency, Thus may determine that damage position, after having had this related criteria, directly quantify similarity degree by the size of numerical value；Phase The biggest like degree, illustrate that crackle occurs the possibility in this position the biggest, when similarity degree is more than 90% when, it is possible to really Recognize crack fault just to occur in this position；

After determining crack position, overall situation response is decomposed into Liang Ge local acknowledgement, determines the size parameter of crackle with this； The rigidity of blade can change at equilbrium position (x=0) place of system；And the existence of crackle so that time blade is intact Rigidity k changes, and the rigidity that the crackle left side is one section becomes k₁, the rigidity that the right is one section becomes k₂；Specifically, according to displacement X>=0 and displacement x<0 or according to acceleration a≤0 and a>0, resolves into Liang Ge local acknowledgement by overall situation response；Further, MATLAB software programming is utilized to obtain the spectrogram of each local acknowledgement, it is thus achieved that locally natural frequency value ω₁And ω₂；Then will The difference of two frequencies obtained contrasts, so that it is determined that the order of severity of crackle；

Relative variation according to the difference of local acknowledgement's intrinsic frequency, i.e. intrinsic frequency identifies the order of severity of crackle:

${\mathrm{\&Delta;\&omega;}}_{1,2}=\frac{{\mathrm{\&omega;}}_2-{\mathrm{\&omega;}}_1}{{\mathrm{\&omega;}}_1}\left(\%\right)$

If two frequency values are equal, illustrate that blade does not exist crack fault；If two frequency values differ in size, blade is described Crackle exists；And if relative variation is bigger, then illustrate that the crackle ratio produced is more serious；Otherwise what then explanation produced splits Line is less.

Ventilating vane method for crack based on vibration the most according to claim 1, it is characterised in that:

The enforcement step of this method is as follows:

First, measuring the overall situation response of blade vibration, this response can be the dynamic respond obtained by displacement transducer, or The acceleration responsive obtained by acceleration transducer；Because blade mostly is dither, so in most cases record is to accelerate Degree response curve；Dynamic respond curve is used the when of theory analysis；

On the one hand, according to the overall situation response of the blade vibration recorded, the location parameter of crackle is determined；The former rank choosing blade are solid There is frequency, measure the big of good blade and any second order intrinsic frequency of the fault blades organized under different Crack Parameters size cases more Little；Calculate the ratio of the frequency square changing value of any two order of this selected several rank intrinsic frequency, in the presence of setting up crackle The characteristic pattern of the intrinsic frequency change duplicate ratio showed；By formulating similarity criterion index, quantify similarity degree, directly Describe crackle by the size of numerical value and the possibility in this position occurs；Frequency square change can than vector similarity criterion index To be obtained by following formula:

$AC(F_1,F_2)=\frac{{\left(F_1^T{F}_2\right)}^2}{\left(F_1^T{F}_1\right)\left(F_2^T{F}_2\right)}$

F in formula₁,F₂Represent the frequency square change ratio that the frequency square change in damage storehouse obtains than vector sum field experiment respectively Vector；Intrinsic frequency change duplicate ratio vector correlation criterion represents two vectorial degrees of correlation；This index is in the range of 0-1；If Being 0 change illustrating the most not cause frequency, blade is intact；If close to 1, this degree of impairment is described Cause the change of frequency, structure frequency change duplicate ratio and the data in damage storehouse in the presence of the crackle therefore obtained by experiment Compare, determine the place, position of crackle；By procedure described above, just it has been determined that got well the position of crackle；

On the other hand, according to the overall situation response of the blade vibration recorded, then the size of crackle is determined；Respond above by the overall situation After the crack position information of blade, according to displacement x>=0 and displacement x<0 or according to acceleration a≤0 and a>0, will Liang Ge local acknowledgement is resolved in overall situation response, determines the size parameter of crackle according to this；MATLAB software programming is utilized to obtain often The spectrogram of individual local acknowledgement, it is thus achieved that locally natural frequency value ω₁And ω₂；The waveform of two parts up and down obtained is reconstructed, Waveform after reconstruct is carried out spectrum analysis, just obtains the natural frequency ω of regional area₁And ω₂；Local is calculated solid by following formula There is a relative variation of frequency:

${\mathrm{\&Delta;\&omega;}}_{1,2}=\frac{{\mathrm{\&omega;}}_2-{\mathrm{\&omega;}}_1}{{\mathrm{\&omega;}}_1}\left(\%\right)$

Utilize Δ ω_1,2This parameter, determines the crackle size information of blade according to the difference of two frequency values；

By procedure described above, just it has been determined that got well crack position and the size information of ventilating vane；

Further, the difference of the sensitivity of this method and traditional additive method is contrasted；Before cracking, it is assumed that complete Office's intrinsic frequency size is ω₀, locally intrinsic frequency (during x > 0) ω₁=ω, locally intrinsic frequency (x < when 0) ω₂=ω；This Time, overall situation natural frequency value is:

${\mathrm{\&omega;}}_0=\frac{2{\mathrm{\&omega;}}_1{\mathrm{\&omega;}}_2}{{\mathrm{\&omega;}}_1+{\mathrm{\&omega;}}_2}=\mathrm{\&omega;}$

After having crackle to produce, it is assumed that global frequencies drops to β ω, local frequencies ω₁Drop to α ω (0 < α < 1), local frequency Rate ω₂Keep constant；So, global frequencies can be expressed from the next:

$\mathrm{\&beta;}\mathrm{\&omega;}=\frac{2\mathrm{\&alpha;}\mathrm{\&omega;}\mathrm{\&omega;}}{\mathrm{\&alpha;}\mathrm{\&omega;}+\mathrm{\&omega;}}=\frac{2\mathrm{\&alpha;}\mathrm{\&omega;}}{1+\mathrm{\&alpha;}}$

Being changed to of global frequencies:

${\mathrm{\&Delta;\&omega;}}_0=(1-\mathrm{\&beta;})\mathrm{\&omega;}=\frac{1-\mathrm{\&alpha;}}{1+\mathrm{\&alpha;}}\mathrm{\&omega;}$

The difference of local frequencies is:

Δ ω=(1-α) ω > Δ ω₀

So identifying that severe crack degree is more much higher than based on global frequencies sensitivity based on local frequencies difference.