CN114323514B

CN114323514B - Multi-blade vibration fatigue test method and system

Info

Publication number: CN114323514B
Application number: CN202011041401.3A
Authority: CN
Inventors: 黄振东; 王海涛; 贾林
Original assignee: AECC Commercial Aircraft Engine Co Ltd
Current assignee: AECC Commercial Aircraft Engine Co Ltd
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2023-06-30
Anticipated expiration: 2040-09-28
Also published as: CN114323514A

Abstract

The invention provides a multi-blade vibration fatigue test method, which outputs a superposition signal of a plurality of input signals, thereby driving a vibration table to work, wherein the frequencies of the plurality of input signals are respectively the same as the natural frequencies of a plurality of blades mounted on the vibration table; obtaining vibration signals of each blade; obtaining a table top acceleration time domain signal of a vibrating table, and decomposing the table top acceleration time domain signal into a plurality of excitation signals through time-frequency conversion and inversion conversion; acquiring a phase difference between a corresponding vibration signal and an excitation signal in real time; the amplitude values of the plurality of input signals are adjusted to enable each blade to vibrate under the respective target amplitude, and meanwhile, the frequencies of the plurality of input signals are adjusted to keep the phase difference between each vibration signal and the excitation signal constant. By the multi-blade vibration fatigue test method, the multi-blade vibration fatigue test can be simultaneously carried out by using a single vibration table, wherein each blade can resonate under the natural frequency of the blade.

Description

Multi-blade vibration fatigue test method and system

Technical Field

The invention relates to a multi-blade vibration fatigue test method and a multi-blade vibration fatigue test system.

Background

Fatigue failure is one of the main failure modes of engine blades. As a key part of an aeroengine, the blade is subjected to fatigue assessment in a test mode no matter in a scientific research stage or a mass production stage so as to obtain key parameters such as fatigue life, limit and the like. At present, a mature standard requirement exists for a vibration fatigue test of the first-order natural frequency of an engine blade, and the vibration fatigue test is widely applied to model development.

In general, at the natural frequency of a single blade, an electrodynamic vibration table can be used to apply a constant frequency alternating load to the single blade to perform a fatigue test. The thrust of the common electric vibration table can reach 30 KN-100 KN, and the thrust required for developing a conventional blade fatigue test is about 10 KN.

The inventor analysis considers that only a single blade vibration fatigue test is carried out on one vibration table at a time, so that the thrust of the vibration table does not work effectively and energy is wasted. Meanwhile, when the blade batch vibration test is needed, the whole test period is long, the efficiency is low, and the cost is high. If the multi-blade vibration fatigue test is carried out through fixed frequency excitation, the difference of the inherent frequencies among different blades is ignored, and the resonance of each blade under the inherent frequency cannot be ensured; meanwhile, the frequency deviation of the blade occurs due to boundary change in the test process, which is ignored, so that the test precision is low and the result is inaccurate.

Accordingly, the present invention is intended to provide a multi-blade vibration fatigue test method that can simultaneously perform multi-blade vibration fatigue tests in which each blade resonates at its own natural frequency using a single vibration table.

Disclosure of Invention

The invention aims to provide a multi-blade vibration fatigue test method, which can simultaneously carry out multi-blade vibration fatigue test by utilizing a single vibration table, wherein each blade can resonate under the natural frequency of the blade.

The invention provides a multi-blade vibration fatigue test method, which comprises the following steps: outputting a superimposed signal of a plurality of input signals, whereby the vibration table is driven to operate, wherein the frequencies of the plurality of input signals are respectively identical to the natural frequencies of a plurality of blades mounted to the vibration table, and the natural frequencies of the respective blades differ from each other by a predetermined degree; obtaining vibration signals of each blade; the method comprises the steps of obtaining a table top acceleration time domain signal of the vibrating table, and decomposing the table top acceleration time domain signal into a plurality of excitation signals through time-frequency conversion and inversion conversion, wherein the excitation signals and the vibration signals of each blade are in one-to-one correspondence through determining that frequency difference is in a preset range; acquiring a phase difference between a corresponding vibration signal and an excitation signal in real time; and taking the vibration amplitude of the vibration signals of each blade as a control variable, adjusting the amplitude of the plurality of input signals to enable each blade to vibrate under the respective target amplitude, and adjusting the frequency of the plurality of input signals to keep the phase difference between each vibration signal and the excitation signal constant.

In one embodiment, the blade vibration fatigue test method further includes: when the vibration frequency of the vibration signal of at least one blade of the plurality of blades is reduced to a certain extent, or when a prescribed number of test cycles is completed, the test is automatically stopped.

In one embodiment, the natural frequencies of the individual blades differ from each other by more than 10%.

In one embodiment, the natural frequency of each blade is obtained by a sinusoidal sweep.

In one embodiment, the time-frequency transform employs a fast fourier transform.

The invention also provides a multi-blade vibration fatigue test system, which comprises a vibration table and a control device, wherein the vibration table is provided with a plurality of blades, and the control device comprises a processor which is configured to execute the multi-blade vibration fatigue test method.

In one embodiment, the multi-blade vibration fatigue test system further comprises: the laser displacement sensors are aligned with the blades respectively and used for collecting vibration signals of the blades and transmitting the vibration signals to the control device, and the acceleration sensors are adhered to the vibrating table and used for collecting table top acceleration time domain signals of the vibrating table and transmitting the vibration signals to the control device.

In one embodiment, the multi-blade vibration fatigue test system further comprises a power amplifier, and the superposition signal is amplified by the power amplifier and drives the vibration table to work.

In one embodiment, the multi-blade vibration fatigue test system further comprises a test fixture in which the blade adapter is integrally formed for being fixed to the vibration table and provided with a plurality of receiving holes; the mortise pieces are respectively arranged in the accommodating holes and are used for respectively clamping blade roots of the blades; the pressing pieces penetrate through the side walls of the accommodating holes respectively, so that the mortises are pressed and fixed respectively.

The present invention also provides a computer readable storage medium having stored thereon computer instructions which when executed by a processor implement the multi-lobe vibration fatigue test method described previously.

According to the multi-blade vibration fatigue test method and system, the superposition signals of the plurality of input signals with the same frequency as the natural frequency of each blade are used as the driving signals, the single vibration table can be used for simultaneously carrying out the multi-blade vibration fatigue test, and the amplitude and the frequency of the tested blade are precisely controlled in real time through the phase tracking resonance residence method, so that each blade can resonate under the natural frequency of the blade all the time, and the test result is more accurate. Moreover, the natural frequencies of the blades are different to a certain extent, so that an error frequency test can be realized, any blade is not interfered by exciting force under the natural frequency of the other blade, and the test precision is high. The multi-blade vibration fatigue test is carried out simultaneously, so that the thrust of the vibration table can be fully utilized, the excitation efficiency and performance of the tester are improved, and the electric power energy of the test system is saved.

In the multi-blade vibration fatigue test system, the test fixture has the advantages of simple structure, convenience in operation and reliability in connection, and can realize stable clamping of the multi-blade.

Drawings

The above and other features, properties and advantages of the present invention will become more apparent from the following description in conjunction with the accompanying drawings and embodiments, in which:

FIG. 1 is a flow chart of an exemplary multi-blade vibration fatigue test method.

FIG. 2 is a schematic diagram of an exemplary multi-blade vibration fatigue test system.

Fig. 3 is a perspective view of an exemplary test fixture.

Fig. 4 is a cross-sectional view of the test fixture of fig. 3.

FIG. 5 is a schematic view of a side pressure tongue and groove member.

FIG. 6 is a schematic view of a rear top mortice component.

Detailed Description

The present invention will be further described with reference to the following detailed description and the accompanying drawings, in which more details are set forth in order to provide a thorough understanding of the present invention, but it will be apparent that the present invention can be embodied in many other forms than described herein, and that those skilled in the art may make similar generalizations and deductions depending on the actual application without departing from the spirit of the present invention, and therefore should not be limited in scope by the context of this detailed description.

Exemplary steps of the multi-lobe vibration fatigue test method F0 of the present invention are shown in fig. 1 and will be described below in connection with the multi-lobe vibration fatigue test system 10 of fig. 2. In the illustrated embodiment, the multi-blade vibration fatigue test method and system of the present invention are described by taking a twin blade as an example, however, it is understood that the plurality of blades in the present invention may be three, four or more than five blades, that is, the multi-blade vibration fatigue test method F0 and the multi-blade vibration fatigue test system 10 of the present invention may have universality and may be applied to the vibration fatigue test of the plurality of blades.

Step S1: a superimposed signal of a plurality of input signals whose frequencies are respectively identical to the natural frequencies of a plurality of blades attached to the vibration table 1 and whose natural frequencies are different from each other by a predetermined degree is outputted, thereby driving the vibration table 1 to operate.

Taking the

double blades

21, 22 as an example, a superimposed signal Xc0 of two input signals Xc1, xc2 is output, and frequencies fc1, fc2 of the input signals Xc1, xc2 are the same as natural frequencies f1, f2 of the

blades

21, 22 attached to the vibration table 1, respectively.

For example, the input signals Xc1, xc2 may each be sinusoidal signals, which may be expressed as:

wherein fc1=2pi ω _c1 ，fc2＝2πω _c2 . Thus, the overlappingSignal->

It will be appreciated that prior to step S1, a plurality of blades need to be mounted to the same vibrating table 1 and the natural frequencies of the individual blades therein are made to differ from each other by a predetermined degree. In fig. 2, both

blades

21, 22 are mounted to the vibrating table 1. As will be described later, a plurality of

blades

21, 22 may be mounted to the vibration table 1 by the test jig 3, the natural frequencies f1, f2 of the two

blades

21, 22 differing by a predetermined degree.

In a preferred embodiment, the natural frequencies of the individual blades differ from each other by more than 10%. Taking the

double blades

21 and 22 as an example, the natural frequency f1 of the blade 21 and the natural frequency f2 of the blade 22 can be different by more than 10%, namely, (f 1-f 2)/f 1 is more than or equal to 10%. In other words, when selecting a plurality of blades as test pieces, blades having natural frequencies different from each other by 10% or more should be selected so as to "error-frequency" the test.

Under the action of simple harmonic force, the acceleration amplitude B of the steady-state vibration of the viscous damping system is as follows:

wherein B is the amplitude of the simple harmonic excitation response; omega _n Is the natural frequency of the system; ζ is a system damping coefficient; b0 is a response value under the action of a static amplitude; omega is the simple harmonic excitation force frequency.

From the above, it can be seen that when the natural frequency ω of the system _n Near the excitation frequency ω, the system vibration acceleration tends to be maximum. The greater the frequency difference, the negligible the effect of the harmonic forces on the system. Thus, by staggering the natural frequencies of the respective blades by a predetermined degree, for example, by more than 10%, the respective excitation forces can be made to act only on the respective blades with negligible effect on the other blades. Conversely, if the natural frequencies of the blades are similar, the blades are easily affected by superposition of excitation forces, and test is performedThe control during the experiment is difficult by using the "dual phase tracking resonance residence" which will be described later.

In a preferred embodiment, the natural frequency f1, f2 of each

blade

21, 22 may be obtained by sinusoidal sweep. For example, after both the

blades

21, 22 are attached to the vibration table 1, the vibration table 1 is started, and the natural frequencies f1, f2 of the

blades

21, 22 are obtained by sinusoidal sweep, respectively. The phase difference between the

blades

21, 22 and the table excitation signal can also be obtained by sine sweep frequency

Blade tip amplitudes A1, A2, damping ratio, and other test parameters. The above-described parameters and other vibration fatigue test-related parameters such as the number of test cycles N0 may be input into the control device 5 in advance. For example, the control device 5 may output the input signals Xc1, xc2 having the same frequencies fc1, fc2 as the natural frequencies f1, f2, respectively, based on the natural frequencies f1, f2. For another example, the control device 5 may set a target amplitude a of the

blades

21, 22, which will be described later, based on the tip amplitudes A1, A2 _t1 、A _t2 。

Step S2: vibration signals of the respective blades are acquired.

Taking the

double blades

21, 22 as an example, vibration signals of the

blades

21, 22 can be acquired by, for example,

laser displacement sensors

41, 42 aligned with the

blades

21, 22, respectively

And->

And then transmitted to a control device 5 to be described later, and the control device 5 acquires vibration signals of the respective blades.

Step S3: the method comprises the steps of obtaining a table top acceleration time domain signal Xs0 of the vibration table 1, and decomposing the table top acceleration time domain signal Xs0 into a plurality of excitation signals through time-frequency conversion and inverse conversion, wherein the excitation signals and the vibration signals of each blade are in one-to-one correspondence through determining frequency differences within a preset range.

In fig. 2, for example, the table acceleration time domain signal Xs0 of the vibration table 1 may be acquired by the acceleration sensor 6 attached to the vibration table 1, and then transmitted to the control device 5, and the control device 5 acquires the table acceleration time domain signal Xs0.

Taking the

double blades

21 and 22 as an example, the table acceleration time domain signal Xs0 can be decomposed into two excitation signals through time-frequency conversion and inversion conversion

A one-to-one correspondence or association may be achieved by determining that the frequency difference between the aforementioned plurality of excitation signals and the vibration signal of each blade is within 0.5%. In other words, (ω) _s1 -ω _b1 )/ω _b1 Less than or equal to 0.5 percent or (omega) _b1 -ω _s1 )/ω _s1 And less than or equal to 0.5%, the excitation signal Xs1 may be corresponding to the vibration signal Xb1 of the blade 21.

In a preferred embodiment, the time-frequency transform may be a fast fourier transform, also referred to as FFT.

Step S4: acquiring a phase difference between a corresponding vibration signal and an excitation signal in real time;

taking the

double blades

21, 22 as an example, the phase differences between the corresponding vibration signals Xb1, xb2 and the excitation signals Xs1, xs2 are acquired in real time. The vibration signal Xb1 may be corresponded to the excitation signal Xs1 by determining that the frequency difference is within the predetermined range, and similarly, the vibration signal Xb2 may be corresponded to the excitation signal Xs 2. Thereby, the phase difference between the vibration signal Xb1 and the excitation signal Xs1 is obtained in real time

And the phase difference between the vibration signal Xb2 and the excitation signal Xs2 +.>

Wherein, the liquid crystal display device comprises a liquid crystal display device,

step S5: the vibration amplitude of the vibration signals of each blade is used as a control variable, the amplitude of the plurality of input signals is adjusted to enable each blade to vibrate under the respective target amplitude, and meanwhile, the frequency of the plurality of input signals is adjusted to keep the phase difference between each vibration signal and the excitation signal constant.

Taking the

double blades

21, 22 as an example, the vibration amplitude A of the vibration signals Xb1, xb2 of the

blades

21, 22 _b1 、A _b2 To control the variables, the amplitude A of the input signals Xc1, xc2 is adjusted _c1 、A _c2 The

blades

21, 22 are respectively set at respective target amplitudes such as A _t1 、A _t2 Vibration is performed. I.e. adjusting amplitude A of input signals Xc1, xc2 _c1 、A _c2 The vibration amplitude A of the vibration signals Xb1, xb2 obtained by measurement _b1 、A _b2 Respectively equal to the target amplitude A _t1 、A _t2 . For example, when the vibration amplitude A _b1 、A _b2 Less than the target amplitude A _t1 、A _t2 In the meantime, the amplitude A of the input signals Xc1, xc2 is adjusted up _c1 、A _c2 The method comprises the steps of carrying out a first treatment on the surface of the Otherwise, the method is down-regulated. It can be appreciated that the amplitude A of the input signals Xc1, xc2 _c1 、A _c2 Can be decomposed from the table acceleration time domain signal Xs0 to form the amplitude A of a plurality of excitation signals Xs1, xs2 _s1 、A _s2 And feedback is obtained.

At the same time, the frequency ω of the input signals Xc1, xc2 is also adjusted _c1 、ω _c2 So that each phase difference acquired in step S4

And remain constant. For example, when the phase difference is->

When the frequency is larger, the frequency omega of the input signals Xc1 and Xc2 is up-regulated _c1 、ω _c2 The method comprises the steps of carrying out a first treatment on the surface of the Otherwise, the method is down-regulated. In this way, the frequency ω of the excitation signals Xs1, xs2 of the vibrating table 1 can be made _s1 、ω _s2 Tracking the frequency ω of the

blades

21, 22 in real time _b1 、ω _b2 By changing the natural frequencies f1 and f2, the

blades

21 and 22 vibrate. According to the resonance residence of phase tracking, the phase difference is kept constant, and then frequency tracking can be realized.

It will be appreciated that steps S2, S3 may be performed simultaneously, and are not required to be performed in sequence.

When executing step S5, the vibration amplitude A is used for _b1 、A _b2 Phase difference

To control the variables, the amplitude A of the input signals Xc1, xc2 is adjusted _c1 、A _c2 Frequency omega _c1 、ω _c2 That is, it means that the step S1 is returned to, that is, the superimposed signal Xc0 of the input signals Xc1, xc2 after adjustment is newly output by using the input signals Xc1, xc2 after adjustment. The whole test process can realize closed-loop control.

The multi-blade vibration fatigue test method F0 may further include the step S4': when the vibration frequency of the vibration signal of at least one blade of the plurality of blades is lowered to a certain extent, or when a prescribed number of test cycles N0 is completed, the test is automatically stopped.

For example, regarding step S4', a determination of whether to stop the test may be performed, which may be performed after step S2, step S3, as shown in fig. 1. If the condition for stopping the test is reached, the test is ended, and if the condition for stopping the test is not reached, the test is continued. For example, the current number of test cycles can be characterized by the number of blade vibrations up to now, which can be detected by the

laser displacement sensors

41, 42, the

laser displacement sensors

41, 42 also detecting the vibration frequencies ω of the vibration signals Xb1, xb2 of the

blades

21, 22 _b1 、ωb2。

As described above, the test cycle number N0 may be stored in the memory 51 of the control device 5 in advance. For example, when a certain blade such as 21 of the plurality of

blades

21, 22 has a frequency such as ω _b1 When the test is lowered by 1%, or when the predetermined number of test cycles N0 is completed, the control device 5 automatically stops the test.

In the actual test, the steps S1, S2, S3, S4 and S5 may be repeated to perform the vibration fatigue test, and the test may be manually ended. In embodiments including step S4', steps S1, S2, S3, S4', S4, and S5 may be repeated, and the test may be automatically ended. Fig. 1 shows an example of one cycle or one frequency of execution, and may be cyclically repeated when actually executed.

In the multi-blade vibration fatigue test method F0, the resonance residence can be carried out on a plurality of test blades simultaneously by adopting the phase tracking resonance residence, the excitation frequency and the energy can be regulated in real time, the test precision is effectively improved, and the over test or the under test is avoided. The closed-loop control in the whole test process is flexible and efficient, manual duty is not needed, and meanwhile, the total test energy consumption is low, so that the test cost, the time cost and the labor cost can be effectively saved.

Fig. 2 shows a multi-lobe vibration fatigue test system 10 according to the present invention.

As described above, the multi-blade vibration fatigue test system 10 includes the vibration table 1, and the vibration table 1 is provided with the plurality of

blades

21, 22. The multi-blade vibration fatigue test system 10 further comprises a control device 5, and the control device 5 may comprise a processor 51. The processor 51 is configured to perform the above-described multi-blade vibration fatigue test method F0. The control device 5 may also comprise a memory 52. The processor 51 and the memory 52 may constitute the control means 5.

The memory 52 serves as a computer-readable storage medium on which computer instructions may be stored, which when executed by the processor 51 implement the multi-lobe vibration fatigue test method F0 described above.

Those of skill in the art will appreciate that computer instructions can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Computer readable storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

Those skilled in the art will appreciate that the processor 51 of the control apparatus 5 may be a combination of computing devices and the memory 52 may be a combination of storage devices. Thus, the control means 5 may be implemented as a combination of a plurality of devices, each comprising a portion of the processor 51 and/or the memory 52. For example, the control device 5 may be embodied as a signal generating collector and a computer which mutually transmit signals. Wherein the computer and signal generating collector each comprise a portion of a processor 51 in communication with each other, and the computer comprises a memory 52 in communication with the processor 51. The signals can be received and outputted by a computer and subjected to signal processing, conversion, analysis and the like, for example, the computer outputs the input signals Xc1, xc2, and then the signal generation collector receives instructions from the computer, outputs driving signals required for the test, for example, outputs the superimposed signal Xc0 of the input signals Xc1, xc2 to a power amplifier 7 to be described later, and the signal generation collector automatically acquires sensor signals and sends them to the computer for analysis, for example, the computer can process them to acquire a phase difference

In the illustrated embodiment, the multi-blade vibration fatigue test system 10 may further include a plurality of laser displacement sensors, aligned with each blade, for acquiring vibration signals of each blade and transmitting the vibration signals to the control device 5. In fig. 2, the multi-blade vibration fatigue test system 10 includes two

laser displacement sensors

41, 42, the laser points being aligned with the tips of the

blades

21, 22, respectively, and vibration signals Xb1, xb2 of the

blades

21, 22 are collected and transmitted to a processor 51 of the control device 5. The

laser displacement sensors

41 and 42 can measure the position, displacement, and other changes of the object to be measured in a noncontact manner by using a laser technique.

The multi-blade vibration fatigue test system 10 may further include an acceleration sensor 6 attached to the vibration table 1 for acquiring a table acceleration time domain signal Xs0 of the vibration table 1 and transmitting the vibration signal Xs0 to the control device 5. In fig. 2, an acceleration sensor 6 is attached to the vibrating table 1, and a table acceleration time domain signal Xs0 of the vibrating table 1 is acquired and transmitted to a processor 51 of the control device 5. The acceleration sensor 6 may measure the vibration acceleration of the object.

In the illustrated embodiment, the multi-blade vibration fatigue test system 10 may further include a power amplifier 7, and the superimposed signal Xc0 is amplified by the power amplifier 7 to drive the vibration table 1 to operate. In other words, the power amplifier 7 amplifies the driving signal input through the control device 5, that is, the superimposed signal Xc0, and outputs the amplified driving signal, so that the vibration table 1 is driven to operate, and the vibration table 1 receives the amplified driving signal through the power amplifier 7 and reciprocates up and down through the table body, thereby generating a vibration waveform required for the test.

As previously described, the multi-blade vibration fatigue test system 10 may further include the test fixture 3. Fig. 3 to 6 show an example configuration of the test jig 3 with a double blade clamped as an example. The test fixture 3 includes a blade adapter 31, a plurality of tongue-and-groove members (two tongue-and-

groove members

81, 82 in the drawing) and a plurality of pressing members (two

pressing members

91, 92 in the drawing). It is to be understood that the drawings are by way of example only and are not drawn to scale and should not be construed to limit the true scope of the invention.

It should also be understood that the formation of a first feature over or on a second feature described in this specification may include embodiments in which the first and second features are formed in direct communication, and may also include embodiments in which additional features are formed between the first and second features, such that there may be no direct communication between the first and second features. Further, where a first element is described as being coupled or combined with a second element, the description includes embodiments in which the first and second elements are directly coupled or combined with each other, and also includes embodiments in which one or more other intervening elements are added to indirectly couple or combine the first and second elements with each other.

The blade adapter 31 may be integrally formed for fixing to the vibration table 1, and provided with a plurality of receiving holes (in fig. 4, two receiving holes 321, 322). In fig. 4, the two receiving

holes

321, 322 are symmetrically disposed, and may be, for example, communicated with each other, implemented as both ends of one through hole. For the double-blade test, the symmetrical double-blade structure can enable the whole gravity center of the test piece to coincide with the center of the moving coil, reduce unbalanced load moment, reduce the transverse displacement of the moving coil in the test process, improve the test precision and reduce the abrasion of the moving coil.

The blade adapter 31 may be provided to include a circular table 311 and a boss 312 provided on the circular table 311. Respective receiving

holes

321, 322 may be provided at respective sides of the boss 312. The portion of the circular table 311 located at the periphery of the boss 312 is provided with a plurality of mounting holes 311a, which are convenient to fix to the vibration table 1.

A plurality of tongue-and-

groove members

81, 82 are provided in the plurality of receiving

holes

321, 322, respectively, for clamping the

blade roots

211, 221 of the

respective blades

21, 22, respectively.

The plurality of pressing

members

91, 92 pass through the side walls of the plurality of receiving

holes

321, 322, respectively, so as to press and fix the plurality of tongue-and-

groove members

81, 82, respectively. For example, the

pressing members

91, 92 may be pressing bolts screwed with screw holes provided on the side walls of the receiving

holes

321, 322.

The plurality of tongue-and-groove members may include a side-pressure type tongue-and-groove member 81 and a rear-top type tongue-and-groove member 82.

Referring to fig. 4 and 5, the side pressure type mortise element 81 may include two jaws 812 connected by an elastic deformation portion 811, and the two jaws 812 are pressed by the pressing member 91 to clamp the blade root 211 of the blade 21. The elastic deformation portion 811 may take the form of a metal sheet bent into an arc shape, for example.

Referring to fig. 4 and 6, the aft ejector tongue-and-groove member 82 may have a mounting tongue-and-groove 821 and an aft ejector 822. The blade root 221 of the blade 22 is inserted into the mounting groove 821 and the blade 22 is clamped by the back top 822 against the bottom of the blade root 221. The rear top 822 abuts against the tested blade 22 from the rear so as to achieve the restraint effect in the bench test state. In the illustrated embodiment, the rear top piece 822 is in the form of a rear top bolt, the rear top type tongue-and-groove 82 further comprises a top block 823, and the top block 823 is placed between the rear top piece 822 and the bottom of the blade root 221, and can be tightly attached to the bottom of the blade root 221 to stably and uniformly transmit the jacking force.

When mounting the

blades

21, 22 to the vibration table 1, the two

blades

21, 22 may first be fitted into the respective tongue-and-

groove members

81, 82, respectively. Then, the assembled tongue-and-

groove members

81, 82 are fitted into the receiving

holes

321, 322 of the blade adapter 31, and the tongue-and-

groove members

81, 82 and the blade adapter 31 are fixedly coupled together by the

pressing members

91, 92. Then, the blade adapter 31 is fitted to the table surface of the vibration table 1 through the lower mounting hole 311 a.

The inspector can select which mortice piece to use according to the blade form. The side-pressing tongue-and-groove member 81 is adapted to clamp a cut test piece, and an inner contour surface formed by two claws 812 can be fitted to a blade root 211 or a tenon cut surface of the blade 21. The aft-jacking dovetail slot member 82 is adapted to grip a dovetail-type blade, and the dovetail slot 821 may define an internal contour that corresponds to the blade root 221 or dovetail of the blade 22.

By adopting the test fixture 3, the

pressing members

91 and 92 fix the

mortises

81 and 82 provided with the

blades

21 and 22 in the blade adapter 31, and the

blades

21 and 22 are connected with the vibrating table 1 into a whole through the blade adapter 31, so that stable clamping of the

blades

21 and 22 is realized, the excitation energy output by the vibrating table 1 can be ensured to be used for exciting the

blades

21 and 22, and the utilization rate of the vibrating table is improved.

While the invention has been described in terms of preferred embodiments, it is not intended to be limiting, but rather to the invention, as will occur to those skilled in the art, without departing from the spirit and scope of the invention. For example, the transformation modes in the different embodiments may be combined appropriately. Therefore, any modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention fall within the protection scope defined by the claims of the present invention.

Claims

1. A multi-blade vibration fatigue test method, comprising:

outputting a superimposed signal of a plurality of input signals, whereby the vibration table is driven to operate, wherein the frequencies of the plurality of input signals are respectively identical to the natural frequencies of a plurality of blades mounted to the vibration table, and the natural frequencies of the respective blades differ from each other by a predetermined degree;

obtaining vibration signals of each blade;

the method comprises the steps of obtaining a table top acceleration time domain signal of the vibrating table, and decomposing the table top acceleration time domain signal into a plurality of excitation signals through time-frequency conversion and inversion conversion, wherein the excitation signals and the vibration signals of each blade are in one-to-one correspondence through determining that frequency difference is in a preset range;

acquiring a phase difference between a corresponding vibration signal and an excitation signal in real time;

and taking the vibration amplitude of the vibration signals of each blade as a control variable, adjusting the amplitude of the plurality of input signals to enable each blade to vibrate under the respective target amplitude, and adjusting the frequency of the plurality of input signals to keep the phase difference between each vibration signal and the excitation signal constant.

2. The blade vibration fatigue test method according to claim 1, further comprising:

when the vibration frequency of the vibration signal of at least one blade of the plurality of blades is reduced to a certain extent, or when a prescribed number of test cycles is completed, the test is automatically stopped.

3. The method for testing vibratory fatigue of a blade according to claim 1, wherein,

the natural frequencies of the blades differ from each other by more than 10%.

4. The method for testing vibratory fatigue of a blade according to claim 1, wherein,

the natural frequency of each blade is obtained through sine sweep frequency.

5. The method for testing vibratory fatigue of a blade according to claim 1, wherein,

the time-frequency transformation adopts fast Fourier transformation.

6. A multi-blade vibration fatigue test system, comprising:

a vibration table provided with a plurality of blades; and

a control device comprising a processor configured to perform the multi-lobe vibration fatigue test method of any one of claims 1 to 5.

7. The multi-blade vibration fatigue test system according to claim 6, further comprising:

a plurality of laser displacement sensors aligned with the respective blades, respectively, for collecting vibration signals of the respective blades and transmitting the vibration signals to the control device; and

and the acceleration sensor is adhered to the vibrating table and used for collecting a table top acceleration time domain signal of the vibrating table and transmitting the vibration signal to the control device.

8. The multi-blade vibration fatigue test system according to claim 6, further comprising:

and the power amplifier amplifies the superposition signal and drives the vibrating table to work.

9. The multi-blade vibration fatigue test system according to claim 6, further comprising:

a test fixture comprising:

the blade adapter is integrally formed and used for being fixed on the vibrating table and provided with a plurality of accommodating holes;

the mortise pieces are respectively arranged in the accommodating holes and used for respectively clamping blade roots of the blades; and

the pressing pieces penetrate through the side walls of the accommodating holes respectively, so that the mortises are pressed and fixed respectively.

10. A computer readable storage medium having stored thereon computer instructions which when executed by a processor implement the multi-lobe vibration fatigue test method according to any of claims 1 to 5.