A vibration characteristic test bench for blisk with frictional damping structure

Abstract

The application discloses a vibration characteristic test test-bed for a blisk containing a friction damping structure, mainly comprising a driving module, an external excitation module, a test module and a data analysis module; the application adopts a pull-rod friction damping structure for the design of the blisk, which helps to weaken the coupled vibration of the disc; in order to verify the reliability of the non-contact measurement of the vibration data of the blade tip, the application adopts strain gauge measurement to verify the measurement data; in order to study the coupled vibration mode of the disc, the application adopts a scanning laser vibration meter and a permanent magnet to realize the measurement of the vibration mode of each pitch form of the blisk. The application can test the vibration characteristics of the blisk containing the friction damping structure, study the influence of different rotating speeds and frequency excitation forces on the vibration characteristics of the blisk, and provide data reference for the vibration reduction structure design and engineering application of the blisk.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engineering and technical research and development, and particularly relates to a test bench for testing vibration characteristics of a blisk with a friction damping structure. BACKGROUND

[0002] With the increasing requirements of the aviation industry on the performance of the engine, the specific thrust of the engine is further improved, and the turbine and compressor blades in the aero-engine begin to gradually adopt the blisk structure. Compared with the traditional split blade and disc structure, the blisk structure is simple, avoids the complex blade-disc root and groove connection structure, reduces the engine mass and improves the operating efficiency. Although the blisk structure has lower mass, it is more prone to blade-disc coupling vibration due to the lack of contact friction between the blade and the disc and the close blade-disc stiffness.

[0003] Currently, there are various damping vibration reduction methods applied to blisk vibration reduction, including coating damping, piezoelectric damping and friction damping. Among them, coating damping and piezoelectric damping are mainly used to suppress modal vibration of specified vibration modes, and the effect of wide frequency domain vibration suppression is limited. Friction damping is a common damping method in engineering, and compared with coating damping and piezoelectric damping, friction damping has the advantages of mature technology and economical cost. The rib structure is a common friction damping structure, which has good effect in blade vibration reduction application, and is less used in blisk structure at present.

[0004] In order to ensure that the blisk structure can run safely in the engine group, the designers will measure the vibration parameters of the blisk structure, study its vibration characteristics, and ensure the reliability of the blisk operation. The blisk is prone to pitch vibration, and disc coupling vibration is the dominant type of blisk vibration, so it is necessary to explore the vibration form of each sensitive order of the blisk. Therefore, it is of great significance to pay attention to the change of vibration mode under different excitation frequencies. The vibration signal measurement usually adopts the blade tip timing method, but the blade tip timing has the problem of under-sampling of vibration signal collection. In order to obtain the vibration displacement of the blisk, it is usually necessary to use reconstruction data such as compressive sensing. Therefore, for the blisk structure with friction damping structure under complex operating conditions, it is of great significance to measure the vibration signal and obtain accurate data of the vibration characteristics for the design and manufacture of the blisk, which is beneficial to optimize the design of the blisk structure with damping structure and provide data reference for the actual blisk design. SUMMARY

[0005] In view of the deficiencies of the prior art, the application provides a vibration characteristic test bench for a blisk with a friction damping structure, which measures the vibration characteristic of the blisk with the friction damping structure, and can simulate the actual operation environment of the blisk by adjusting the permanent magnet and the motor. The vibration characteristic under the complex operation environment is measured and analyzed, data reference is provided for the optimization design of the blisk, and the safety operation of the blisk is verified.

[0006] To achieve the above object, the application adopts the following technical solution:

[0007] A vibration characteristic test bench for a blisk with a friction damping structure, comprising a driving module, an external excitation module, a test module and a data analysis module.

[0008] The driving module is used for driving the test piece in the test module to rotate by an external power supply, so as to provide rotation conditions for signal measurement of the test piece.

[0009] The external excitation module is used for providing a periodic excitation force for the test piece in the test module, so as to simulate the airflow excitation force suffered by the blisk test piece during operation.

[0010] The test module is used for testing the blisk test piece, and a plurality of contact and non-contact sensors are arranged to obtain data signals.

[0011] The data analysis module is used for data processing of the electrical signals measured by the test module, and the response characteristic and modal shape of the blisk are obtained by analysis.

[0012] The driving module comprises a servo motor, a belt, a hollow main shaft, a first bearing and a second bearing; the servo motor is connected to the main shaft through the belt, the belt realizes the transmission function from the servo motor to the main shaft, and then the servo motor is used to drive the main shaft and the connected components; the first bearing and the second bearing support the main shaft during rotation.

[0013] The test module comprises an electric slip ring, a blisk, a test support, a strain gauge, an eddy current displacement sensor, a rotating speed sensor and a scanning laser displacement sensor.

[0014] The integral blade disc with the rib structure is connected to the hollow main shaft through a key, a test support is arranged on the periphery of the integral blade disc, and an eddy current displacement sensor and a rotating speed sensor are fixedly installed on the test support, so that the non-contact vibration signal measurement of the integral blade disc is realized; the scanning laser vibration meter is used for scanning measurement of the vibration displacement of the integral blade disc, so that the vibration mode distribution is obtained, and the non-contact measurement of the modal vibration mode of the integral blade disc is realized; strain gauges are installed at positions where the vibration strain of the blade bottom of the integral blade disc is large, the measurement signals pass through the hollow main shaft through wires, the wires are connected to the electric slip ring at the other end of the main shaft, and the signals are transmitted to the data analysis module through the electric slip ring, so that the contact measurement of the vibration signal of the integral blade disc is realized.

[0015] Further improvement of the present application is that the integral blade disc adopts the integral blade disc with the rib structure, the integral blade disc realizes the friction damping effect by adding the rib structure to the blade body, the rib structure dissipates the vibration energy through the friction between the through hole and the blade, and then the vibration amplitude of the integral blade disc is reduced, and the coupled vibration of the blade disc is weakened.

[0016] Further improvement of the present application is that the eddy current displacement sensor and the rotating speed sensor jointly realize the non-contact measurement of the vibration response of the blade tip, the integral blade disc is connected to the main shaft through a key, the rotating speed sensor is arranged above the key groove position to realize the measurement of the rotating speed, and a plurality of eddy current displacement sensors are arranged at the blade tip at a set angle to realize the displacement monitoring of the blade tip of the integral blade disc; based on the blade tip displacement monitoring signals of the displacement sensors at different arrangement angles, the vibration characteristics of the integral blade disc can be obtained by combining the rotating speed sensor; the vibration displacement d s According to the common analysis of the signals of the rotating speed synchronous sensor and the eddy current sensor:

[0017] d s =R*Omega*DeltaT s

[0018] In the formula, R is the radius of the blade tip, Omega is the rotating speed, and the time difference t ref1 -t ref2 is obtained by measuring two signals of the rotating speed sensor; DeltaT s =t measured -t expected is the measurement time difference of the eddy current displacement sensor at the blade tip, and t expected represents the expected measurement time of the sensor when there is no vibration; the vibration characteristic parameters of the integral blade disc can be obtained by combining the blade tip timing algorithm to process the data.

[0019] A further improvement of this invention lies in that the test rig simultaneously employs both contact and non-contact measurement methods to measure the tip response of the integral bladed disk. The non-contact measurement is obtained through computational analysis, while the contact measurement is directly performed using strain gauges. The electrical signals measured by the strain gauges are then analyzed using an analysis module combined with finite element method calculations to obtain the vibration characteristics of the integral bladed disk. The strain gauge contact measurement analysis yields the strain as ε. SG And the blade tip displacement y obtained by non-contact measurement and analysis BTT The strain-displacement relationship was obtained through finite element modal analysis:

[0020] Based on the finite element model, the conversion coefficient K is obtained. mod =y mod / ε mod This conversion factor represents the tip mode displacement y. mod With strain gauge modal strain ε mod ratio;

[0021] Under small excitation, the blade vibration is considered linear, and therefore the actual vibration response and strain conversion coefficient are approximately equal to the conversion coefficient K obtained from the modal analysis. mod Therefore, the strain measurement value ε SG blade displacement y BTT writing:

[0022] y BTT =K mod ·ε SG .

[0023] A further improvement of the present invention is that the external excitation module is used to simulate the excitation force experienced by the overall bladed disk in actual operation. It includes a permanent magnet. By arranging a permanent magnet on the test support, the permanent magnet is used to magnetically excite the overall bladed disk structure to simulate the periodic excitation force experienced by the overall bladed disk.

[0024] A further improvement of this invention is that, considering the influence of external excitation on vibration characteristics, the integral bladed disk is subjected to periodic excitation force from the nozzle during actual operation. The test bench utilizes the force exerted by permanent magnets on the magnetically conductive integral bladed disk to simulate the periodic excitation force on the integral bladed disk. The permanent magnets are fixed to the test support and evenly distributed on the lower side of the integral bladed disk, with a number of permanent magnets of Z1, and the rotational speed of the integral bladed disk reaches n. s At that time, the entire bladed disk is subjected to an excitation Z1n per second. s Therefore, the frequency of the excitation force on the entire bladed disk is:

[0025] f e =Z1n s .

[0026] A further improvement of the present invention is that the scanning laser vibration meter can scan and measure the overall bladed disk vibration displacement distribution to obtain the overall bladed disk vibration mode; according to the excitation force frequency relationship, the frequency of the excitation force on the overall bladed disk can be adjusted by adjusting the number of permanent magnets on the test support; by adjusting the permanent magnets to change the frequency of the excitation force on the overall bladed disk, the scanning laser vibration meter can further measure the mode shape under each pitch diameter.

[0027] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0028] This invention provides a test bench for the vibration characteristics of an integral bladed disk (IBD) with a friction damping structure. The test bench utilizes an IBD with a tie-rib structure, and the friction damping effect between the tie-rib structure and the blades reduces the coupled vibration of the IBD, further ensuring the operational reliability of the IBD. This invention employs both non-contact and contact measurement methods to test and analyze the vibration characteristics of the IBD. Contact measurement is used to verify the results of non-contact measurement, ensuring the validity and accuracy of the measurement results. Furthermore, this invention uses magnetic excitation to simulate the airflow excitation force experienced by the IBD during operation. The frequency of the excitation force can be adjusted by changing the number of permanent magnets, and a scanning laser vibrometer can be used to measure the mode shapes of the IBD under different nodal diameters. This invention can test the vibration characteristics of IBD structures with friction damping, study the influence of different rotational speeds and frequencies of excitation force on the vibration characteristics of the IBD, provide data reference for the design of IBD vibration reduction structures, and help guide engineering application design. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a test bench for testing the vibration characteristics of an integral bladed disk with a friction damping structure according to the present invention.

[0030] Figure 2 This is a schematic diagram of an integral bladed disk structure with friction damping.

[0031] Figure 3 This is a schematic diagram of the external stimulus module and the test module.

[0032] Figure 4 This is a schematic diagram of the test method for this test bench.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1, electric slip ring; 2, servo motor; 3, belt; 4, first bearing; 5, hollow spindle; 6, blisk; 7, strain gauge; 8, permanent magnet; 9, test support; 10, second bearing; 11, eddy current displacement sensor; 12, speed sensor; 13, scanning laser vibration meter; 14, speed sensor mounting bracket; 15, displacement sensor mounting bracket; 16, permanent magnet mounting bracket; 17, pull bar. DETAILED DESCRIPTION

[0035] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] Please refer to Figure 1 The application provides a test bench for analyzing vibration characteristics of a blisk with a friction damping structure, which adds a pull bar structure to the blisk to reduce the blisk coupling vibration of the blisk, and uses contact and non-contact methods to measure the vibration characteristics of the blisk under the action of rotation speed and magnetic excitation. The test bench mainly includes a driving module, an external excitation module, a test module and a data analysis module.

[0037] The driving module mainly includes a servo motor 2, a belt 3, a first bearing 4, a hollow spindle 5 and a second bearing 10. The servo motor 2 is connected to the hollow spindle 5 through the belt 3, and the transmission from the servo motor 2 to the hollow spindle 5 is realized through the belt 3, so that the servo motor 2 can drive the spindle 5 and its connected components, and the first bearing 4 and the second bearing 10 support the hollow spindle 5 during rotation.

[0038] The test module mainly includes an electric slip ring 1, a blisk 6, a strain gauge 7, a test support 9, an eddy current displacement sensor 11, a speed sensor 12 and a scanning laser vibration meter 13. The blisk 6 with a pull bar structure is connected to the hollow spindle 5 through a key, and the test support 9 is arranged on the periphery of the blisk. The eddy current displacement sensor 11 is fixedly installed on the test support 9, and the speed sensor 12 is also arranged on the test support 9 to realize non-contact vibration signal measurement of the blisk 6. At the same time, the scanning laser vibration meter 13 can scan and measure the vibration displacement of the blisk 6 to obtain the vibration mode distribution and realize non-contact measurement of the modal vibration mode of the blisk 6. In addition, the strain gauge 7 is installed on the bottom of part of the blades of the blisk, the measurement signal passes through the hollow spindle 5 through the wire, the wire is connected to the other end of the electric slip ring 1, and the signal is transmitted to the data analysis module through the electric slip ring 1 to realize contact measurement of the vibration signal of the blisk.

[0039] The external excitation module mainly comprises a test support 9 and a permanent magnet 10. The external excitation module is used for simulating the excitation force borne by the blisk 6. The permanent magnet 10 is arranged on the test support 9, and the blisk 6 is magnetically excited by the permanent magnet 10 to simulate the periodic excitation force borne by the blisk.

[0040] Referring to Figure 2 The blisk with the friction damping structure mainly comprises a blisk 6 and a pull rod 16. The friction damping effect is achieved by adding the pull rod structure to the blade body of the blisk 6. In the vibration process, the vibration energy is dissipated through the mutual friction between the pull rod structure and the blade, thereby helping to reduce the blisk coupling vibration and improve the operation reliability of the blisk.

[0041] Referring to Figure 3 The external excitation module and the test module structure are as follows: the eddy current displacement sensor 11 is fixed to the test support 9 through a displacement sensor mounting bracket 15, the speed sensor 12 is fixed to the test support 9 through a speed sensor mounting bracket 14, and the permanent magnet 8 is fixed to the test support 9 through a magnet mounting bracket 16. The speed sensor 12 is arranged above the key connection between the blisk 6 and the hollow main shaft 5 to measure the speed. The vibration characteristics of the blisk can be obtained by analyzing the signals monitored by the multiple eddy current displacement sensors 11 based on different arrangement angles and the speed sensor 12. The vibration displacement d s The vibration characteristics of the blisk can be obtained by analyzing the signals monitored by the multiple eddy current displacement sensors 11 based on different arrangement angles and the speed sensor 12.

[0042] d s =R x Omega x Delta t s

[0043] In the formula, R is the blade tip radius, Omega is the speed, and the time difference t ref1 -t ref2 is obtained by measuring two signals by the speed sensor 12. Delta t s =t measured -t expected is the time difference measured by a certain blade tip eddy current displacement sensor 11, and t expected represents the expected measurement time of the sensor when there is no vibration. Further, the vibration characteristics parameters of the blisk can be obtained by combining the data processing with the blade tip timing algorithm.

[0044] The contact measurement mode is directly measured by the strain gauge 7 installed in the high strain area close to the bottom. The blade tip vibration displacement of the blisk 6 is obtained by analyzing the electric signal measured by the strain gauge 7 through the analysis module, which is used for verifying the non-contact measurement. The strain of the strain gauge 7 is epsilon SG and the blade tip displacement y BTTThe relationship between strain and displacement can be obtained by finite element modal analysis:

[0045] According to the finite element model, the conversion coefficient K mod = y mod / ε mod can be obtained, which represents the ratio of the blade tip modal displacement y mod to the strain gauge modal strain ε mod .

[0046] For small excitation, the blade vibration can be regarded as linear vibration, and the actual vibration response is approximately equal to the conversion coefficient K mod of the modal analysis result, so the blade displacement y SG of the strain measurement value ε BTT can be written as:

[0047] y BTT = K mod · ε SG

[0048] The permanent magnet 8 is fixed to the test support 9 through the magnet mounting frame 16, and is used to simulate the influence of external excitation force on the vibration characteristics of the overall blade disc. In actual operation, the overall blade disc is subjected to periodic excitation force from the nozzle. The test bench uses the force of the permanent magnet 8 acting on the magnetically conductive overall blade disc 6 to simulate the periodic excitation force received by the overall blade disc. The permanent magnet 8 is fixed to the test support 9 through the magnet mounting frame 16 and is uniformly arranged on the lower side of the overall blade disc 6. The number of permanent magnets 8 is Z1, and when the rotating speed of the overall blade disc 6 reaches n s , the overall blade disc 6 is subjected to Z1n s excitations per second, so the frequency of the excitation force received by the overall blade disc 6 is:

[0049] f e = Z1n s

[0050] The scanning laser vibration meter 13 in the application can scan and measure the vibration displacement distribution of the overall blade disc 6 to obtain the vibration mode of the overall blade disc 6. According to the above excitation force frequency relationship, the number of permanent magnets 8 on the test support can be adjusted to adjust the excitation force frequency received by the overall blade disc 6. By adjusting the excitation force frequency received by the overall blade disc 6, the scanning laser vibration meter 13 can further measure the modal vibration mode of the overall blade disc 6 under each pitch diameter form.

[0051] In order to further understand the overall blade vibration characteristic test bench and test method with friction damping structure, the operation steps will be described.

[0052] The rotating blade tip timing vibration state monitoring test process is:

[0053] (1) Install non-contact sensors: install eddy current displacement sensors 11 to the corresponding preset positions of the test support 9 respectively, as the blade tip timing sensors; install the rotating speed sensor 12 in line with the rotating shaft key position; use a direct current power supply to power the sensors, and output signals to the data collector for setting and debugging;

[0054] (2) Install and adjust the blisk: mark the blade number, arrange the strain gauges 7 in the area with larger vibration strain on the blade bottom according to the finite element analysis results; adjust the position and height of the eddy current displacement sensors 11, and calibrate; set the rotating speed signal through the PLC and write it into the motor driver, and set the motor rotating speed;

[0055] (3) Verify the non-contact measurement results: analyze the strain gauge 7 measurement signal through the finite element calculation results, and obtain the blade tip vibration displacement response. Obtain the signal through the eddy current displacement sensor 11 and the rotating speed sensor 13, and use the compressed sensing method to reconstruct the vibration displacement response, and verify it with the contact measurement.

[0056] (4) Apply excitation force and collect signals: adjust the distribution of the permanent magnet 8, apply excitation force to the blisk 6, simulate the airflow excitation force borne by the blisk 6 during operation. Collect the blade vibration signals under the working condition by using the blade tip timing method, and use the scanning laser vibration meter 13 to scan and measure the modal shape of the blisk 6, and collect multiple groups of data for the next signal processing;

[0057] (5) Repeat steps (2) to (4), adjust the motor rotating speed, and obtain the blade vibration signals under different operating conditions.

[0058] Finally, it should be noted that: the above embodiments are only preferred embodiments of the present application, and are used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by the same, without departing from the spirit and scope of the present application. Any modification or equivalent replacement, which does not depart from the spirit and scope of the present application, should be covered within the protection scope of the claims of the present application.

Claims

1. A test bench for testing vibration characteristics of a blisk containing a frictional damping structure, characterized by, The application relates to a test device for a blisk, which comprises a driving module, an external excitation module, a test module and a data analysis module. The driving module is used for driving the test module to rotate by an external power supply, so as to provide a rotating condition for signal measurement of the test piece. The external excitation module is used for providing a periodic excitation force for the test piece in the test module, so as to simulate the airflow excitation force suffered by the blisk during operation. The test module is used for testing the blisk, and a plurality of contact and non-contact sensors are arranged to obtain data signals; the test module comprises an electric slip ring, a blisk, a test support, a strain gauge, an eddy current displacement sensor, a rotating speed sensor and a scanning laser vibration tester; the blisk with a rib structure is connected to a hollow spindle through a key, the test support, the eddy current displacement sensor and the rotating speed sensor are fixedly installed on the test support, and are used for realizing non-contact vibration signal measurement of the blisk; the scanning laser vibration tester is used for scanning and measuring vibration displacement of the blisk, so as to obtain a vibration mode distribution and realize non-contact measurement of a modal vibration mode of the blisk; the strain gauge is installed at a position with large vibration strain of the blade bottom of the blisk, a signal is transmitted to the data analysis module through the hollow spindle and the electric slip ring, and contact measurement of the vibration signal of the blisk is realized. The eddy current displacement sensor and the rotating speed sensor jointly realize the non-contact measurement of the vibration response of the blade tip, the blisk is connected to the main shaft through a key, the rotating speed sensor is arranged above the key groove position to realize the measurement of the rotating speed, and a plurality of eddy current displacement sensors are arranged on the blade tip at a set angle to realize the displacement monitoring of the blade tip of the blisk; based on the blade tip displacement monitoring signals of the displacement sensors with different arrangement angles, the vibration characteristics of the blisk can be obtained by combining the rotating speed sensor; the vibration displacement of any blade According to the common analysis of the signals of the rotating speed synchronous sensor and the eddy current sensor, wherein is the blade tip radius, is the rotational speed, measured by the rotational speed sensor as the difference between two signal times is obtained; is the time difference measured by the eddy current displacement sensor at the blade tip, represents the expected measurement time of the sensor assuming no vibrations; the overall blisk vibration characteristic parameters are obtained by processing the data in combination with the blade tip timing algorithm; The data analysis module is used for processing data of the electric signal measured by the test module, and analyzing and obtaining response characteristics and a modal vibration mode of the blisk.

2. The test bench for testing vibration characteristics of a blisk with frictional damping structure according to claim 1, wherein The driving module comprises a servo motor, a belt, a hollow spindle, a first bearing and a second bearing; the servo motor is connected to the spindle through the belt, the belt realizes transmission from the servo motor to the spindle, and then the servo motor is used for driving the spindle and connected components; the first bearing and the second bearing play a supporting role during rotation of the spindle.

3. The test bench for testing vibration characteristics of a blisk with frictional damping structure according to claim 1, wherein The blisk adopts a blisk with a rib structure, the blisk realizes friction damping effect by adding a rib structure to the blade body, the rib structure dissipates vibration energy through friction between a through hole and the blade, so as to reduce vibration amplitude of the blisk and weaken coupled vibration of the blisk.

4. The test bench for testing vibration characteristics of a blisk with frictional damping structure according to claim 1, wherein The test bed simultaneously uses a contact measurement method and a non-contact measurement method to measure the blade tip response of the blisk, wherein the non-contact measurement is obtained through calculation and analysis, the contact measurement method is directly measured through a strain gauge, and the vibration characteristics of the blisk are obtained through analysis of an electric signal measured by the strain gauge in combination with finite element calculation and analysis; the strain gauge contact measurement analysis can obtain the strain and the blade tip displacement obtained through the non-contact measurement analysis The relationship between the strain and the displacement is obtained through finite element modal analysis: According to the finite element model, a conversion coefficient is obtained which represents the tip mode displacement to the strain gage mode strain ratio; The blade vibration under small excitation is regarded as linear vibration, and the conversion coefficient of the actual vibration response and strain is approximately equal to the conversion coefficient of the modal analysis result , so the blade displacement of the strain measurement value is written as: 。 5. The test bench for testing vibration characteristics of a blisk with frictional damping structure according to claim 1, wherein The external excitation module is used for simulating the excitation force suffered by the blisk during actual operation, and comprises a permanent magnet; the permanent magnet is arranged on the test support, the blisk structure is magnetically excited by the permanent magnet, and the periodic excitation force suffered by the blisk is simulated.

6. The test bench for testing vibration characteristics of a blisk with frictional damping structure according to claim 5, wherein Considering the influence of external excitation on vibration characteristics, the overall blade is subjected to periodic excitation force from the nozzle in actual operation. The test bench uses permanent magnets to simulate the periodic excitation force on the overall blade. The permanent magnets are evenly arranged on the underside of the overall blade, and the number of permanent magnets is . When the overall blade reaches a speed of , the overall blade is subjected to excitation times per second, so the frequency of the excitation force on the overall blade is: 。 7. The test bench for testing vibration characteristics of a bladed disk with frictional damping structure according to claim 6, wherein The scanning laser vibration tester can scan and measure vibration displacement distribution of the blisk, and obtain a vibration mode of the blisk; according to a frequency relationship formula of the excitation force, the number of the permanent magnets on the test support is adjusted, so as to adjust the excitation force frequency suffered by the blisk; the permanent magnets are adjusted to change the excitation force frequency suffered by the blisk, and the scanning laser vibration tester further measures the modal vibration mode under each pitch diameter mode.

Images