An experimental apparatus and method for LDV self-following modes with a rotating structure.

Abstract

This invention relates to the field of structural vibration dynamics experimental technology, and particularly to an LDV self-following modal experimental device and method for rotating structures. The experimental device includes: a stationary structure, a rotating structure, and a driving structure. The stationary structure includes a laser vibrometer and a slip ring stator. The rotating structure includes a slip ring rotor, a light-transmitting shaft, a shaft system, a second reflector, a piezoelectric ceramic sheet, and a test object. A third reflector is also mounted on the light-transmitting shaft. The piezoelectric ceramic sheet is mounted on the test object. One or more groups of piezoelectric ceramic sheets are used to apply excitation to the test object, while the remaining groups of piezoelectric ceramic sheets and the laser vibrometer are used to collect the vibration signals of the test object. The first, second, and third reflectors together control the laser emitted by the laser vibrometer, focusing it onto the test object. The circumferential adjustment of the laser's focusing position on the test object is possible via the light-transmitting shaft and the shaft system. This invention provides an LDV self-following modal experimental device and method for rotating structures, solving the problem of difficulties in conducting modal experiments on rotating mechanical structures under rotating conditions.

Description

Technical Field

[0001] This invention relates to the field of structural vibration dynamics experimental technology, and in particular to an LDV self-following mode experimental device and method for rotating structures. Background Technology

[0002] To adapt to the increasing proportion of intermittent renewable energy sources leading to more severe grid load fluctuations, it is necessary to further develop variable-speed pumped storage technology. Frequent variable-speed operation will bring pressure pulsations over a wider frequency range, increasing the risk of turbine resonance.

[0003] In existing technologies, modal experiments on rotating structures such as turbine runners are often conducted under static conditions. Related studies show that when a turbine runner rotates in water, its vibration modes split into traveling waves (in the same direction as rotation) and backward waves (in the opposite direction of rotation). The natural frequency of the former decreases with increasing rotational speed, while that of the latter increases. Furthermore, changes in modal parameters such as mode shape and damping also occur. This increases the difficulty of resonance prediction and poses a significant challenge to the design and operation of variable-speed pump-turbine pumped-storage units. The variation law of modal parameters and the fluid-structure interaction mechanism of underwater rotating structures still need further investigation. Therefore, there is an urgent need for a self-following modal experimental device for rotating structures to address these issues. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an LDV self-following modal experimental device and method for rotating structures, which extracts modal parameters such as natural frequencies, modal damping, and mode shapes of test objects in air or water, thereby solving the problem of difficulties in conducting underwater rotating structure modal experiments in existing technologies.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] A rotating LDV self-following modal experimental setup includes a stationary structure, a rotating structure, and a driving structure.

[0007] The rotating structure rotates under the drive of the driving structure;

[0008] The static structure includes a laser vibrometer 1 and a slip ring stator 302;

[0009] The rotating structure includes a slip ring rotor 304, a light-transmitting shaft 4, a shaft system 8, a second reflector 5, a piezoelectric ceramic sheet 6, and a test object 7; the light-transmitting shaft 4 includes a vertical shaft and a horizontal shaft;

[0010] The slip ring stator 302 is fixed on the bracket, and the slip ring rotor 304 is rotatably sleeved inside the slip ring stator 302;

[0011] One end of the vertical shaft of the light-transmitting shaft 4 is fixedly connected to the slip ring rotor 304, and the other end is fixedly connected to one end of the shaft system 8; the other end of the shaft system 8 is fixedly connected to the test object 7.

[0012] The piezoelectric ceramic sheets are arranged in a 6-circle pattern on the test object 7;

[0013] The light transmission shaft 4 is connected to a drive structure on its outer side of the vertical axis. The drive structure drives the light transmission shaft 4 to rotate, thereby driving the shaft system 8 to rotate.

[0014] The light transmission axis 4 is equipped with a third reflector 403 inside the vertical axis and a second reflector 5 outside the horizontal axis of the light transmission axis 4.

[0015] The two ends of the second reflector 5 are rotated and fixed on the horizontal axis of the light transmission axis 4. Adjust the angle between the second reflector 5 and the horizontal direction to adjust the focusing position of the laser measuring point of the laser vibrometer 1 on the test object 7.

[0016] The optical axis 4 and the axis system 8 can rotate circumferentially to adjust the focusing position of the laser measuring point on the test object 7;

[0017] The signal line 301 is connected to the piezoelectric ceramic sheet 6 in a one-to-one correspondence;

[0018] The second reflector 5 and the third reflector 403 are used to control the laser emitted by the laser vibrometer 1 and adjust the focusing position of the laser test object 7.

[0019] The experimental setup is used to determine the natural frequency, damping, and mode shape of the test object 7.

[0020] Preferred,

[0021] The stationary structure also includes a first reflector 2, which is fixed directly above the slip ring rotor 304 at a 45° angle to the horizontal plane.

[0022] The laser vibration meter 1 is fixed in the same horizontal plane as the first reflector 2.

[0023] Preferred,

[0024] The slip ring stator 302 is provided with signal line through holes 305 arranged around its perimeter;

[0025] The outer side of the optical axis 4 is provided with signal line through hole 305 and signal line through hole 402 arranged around it.

[0026] The two ends of the shaft system 8 are respectively provided with signal line through hole 3 805 and signal line through hole 401 corresponding to signal line through hole 2 402;

[0027] The shaft system 8 is connected to the test object 7 at one end, and a shaft system groove 802 is provided at the corresponding signal line through hole 801; the test object 7 is provided with a test object groove 702 corresponding to the shaft system groove 802, which connects to the piezoelectric ceramic sheet 6.

[0028] The signal line 301 enters the shaft system 8 through the signal line through hole 305, then through the signal line through hole 402, then through the signal line through hole 305, and then exits through the signal line through hole 401, fitting into the shaft system groove 802 and the test object groove 702 to connect the piezoelectric ceramic sheet 6.

[0029] Preferred,

[0030] The piezoelectric ceramic sheet 6 is connected to the test object 7 with glue.

[0031] Preferred,

[0032] The light-transmitting shaft 4 and the slip ring rotor 304 are connected by a nut riveting.

[0033] Preferred,

[0034] The vertical shaft of the light transmission axis 4 is connected to the shaft system 8 at one end, which is provided with a threaded hole 404. The shaft system 8 is provided with a plurality of positioning holes 806 corresponding to the threaded hole 404 of the light transmission axis in the circumferential direction. The threaded hole 404 of the light transmission axis can be connected to each of the positioning holes 806 by screws, so as to realize the circumferential adjustment of the laser measuring point of the laser vibrometer 1 on the surface 7 of the test object.

[0035] Preferred,

[0036] The drive structure is a motor 10;

[0037] The outer side of the light-transmitting shaft 4 is keyed to a pulley 401 in the vertical direction;

[0038] The motor 10 is connected to the pulley 401 via belt drive, thereby driving the slip ring rotor 304, shaft system 8, and test object 7 to rotate.

[0039] Preferred,

[0040] The shaft system 8 is fixedly connected to an external stationary component via bearings.

[0041] The shaft system 8 is provided with a locking component 803 at one end near the test object 7, and the locking component 803 is connected to the test object 7 by bolts.

[0042] A method for experimental analysis of LDV self-following modes with a rotating structure, employing the aforementioned experimental apparatus for LDV self-following modes with a rotating structure, specifically comprising:

[0043] When conducting modal experiments, the drive structure drives the light-transmitting shaft 4 to rotate, which in turn drives the slip ring rotor 302, the shaft system 8 and the test object 7 to rotate.

[0044] Under rotating conditions, one or more groups of signal lines 301 connected to external signal sources transmit external voltage signals to the corresponding piezoelectric ceramic sheets 6. The corresponding group of piezoelectric ceramic sheets 6 applies excitation to the test object 7, causing it to generate vibration signals. The remaining groups of piezoelectric ceramic sheets 6 serve as data acquisition units, transmitting data to a signal acquisition card via the corresponding signal lines 301. This data is used to analyze the vibration signals of the test object 7 to obtain the natural frequency and damping of the test object 7.

[0045] Meanwhile, the laser from the laser vibrometer 1 passes through the slip ring 3 and the optical axis 4 in sequence, and is reflected by the second reflector 5 and the third reflector 403, and is focused onto the surface of the test object 7, and transmitted to the signal acquisition card for analysis of the vibration mode of the test object 7.

[0046] Specifically, by arranging several measuring points on n diameters on the surface of the test object 7, with at least one measuring point near the outer edge of the test object 7, the imaginary part amplitude of the frequency response function corresponding to the forward or backward traveling wave mode of each measuring point is extracted to obtain the mode shape of the test object 7 splitting into forward and backward traveling waves under the n-diameter mode.

[0047] Preferred,

[0048] The positions of the n diameters where the measuring points need to be placed are selected by trial and error, so as to avoid the diameter where the measuring point is located on the nodal diameter;

[0049] The test object 7 with radius r contains s (s≥1) mode shapes. Several measuring points are uniformly arranged on at least s+1 concentric circles, and the radius of the (s+1)th concentric circle is ri=r / s.

[0050] The beneficial effects of this invention are:

[0051] This invention provides an LDV self-following modal experimental device and method for rotating structures, addressing the difficulties in conducting underwater rotating structure modal experiments in existing technologies. Based on modal experiments of rotating structures in water or high-density fluids, it clarifies the variation law of modal parameters such as natural frequency, damping, and mode shape of rotating structures with rotational speed during operation in fluid, providing a reference for the development of structural dynamics theory. Simultaneously, it can provide a reference for the design of pump impellers, turbine impellers, ship propellers, and bearings immersed in high-density media. Furthermore, it can provide a reference for the variable-speed operation of variable-speed pumped storage units, avoiding resonance during operation at specific speeds. Attached Figure Description

[0052] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0053] Figure 1 This is a schematic diagram of the overall structure of the LDV self-following modal experimental device with a rotating structure according to the present invention;

[0054] Figure 2 This is a schematic diagram of a slip ring structure;

[0055] Figure 3 This is a schematic diagram of the optical axis structure;

[0056] Figure 4 This is a schematic diagram of the shaft system structure;

[0057] Figure 5 This is a schematic diagram of the test object and the arrangement of the piezoelectric ceramic sheet (sensor) in the LDV self-following modal experimental device with rotating structure of the present invention;

[0058] Figure 6 This is a schematic diagram of the measurement point arrangement principle applicable to extracting mode vibration modes containing 6 or fewer nodal diameters and 4 or fewer nodal circles in the LDV self-following modal experimental device of the rotating structure of the present invention;

[0059] Figure label:

[0060] 1 Laser Vibration Analyzer (LDV), 2 First Reflector, 3 Slip Ring, 4 Optical Shaft, 5 Second Reflector, 6 Piezoelectric Ceramic Sheet (PZT), 7 Test Object, 8 Shaft System, 9 Belt, 10 Motor, 301 Signal Line, 302 Slip Ring Stator, 303 Locking Component, 304 Slip Ring Rotor, 305 Signal Line Through Hole 1, 401 Pulley, 402 Signal Line Through Hole 2, 403 Third Reflector, 404 Optical Shaft Threaded Hole, 405 Knob, 801 Signal Line Through Hole 4, 802 Shaft System Groove, 803 Locking Component, 804 Bearing, 805 Signal Line Through Hole 3, 806 Positioning Hole, 701 Test Object Threaded Hole, 702 Test Object Groove. Detailed Implementation

[0061] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the following embodiments are given for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0062] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] The following is combined Figures 1 to 6 This invention describes a rotating LDV self-following modal experimental device.

[0065] like Figures 1 to 6 As shown, this invention provides a rotating LDV self-following modal experimental device. This experimental device is used to collect vibration signals in a stationary coordinate system and a rotating coordinate system. It includes: a laser vibrometer 1, a first reflector 2, a slip ring 3, a light-transmitting shaft 4, a second reflector 5, a piezoelectric ceramic sheet 6, a test object 7, a shaft system 8, and a drive structure. The slip ring 3 includes a slip ring stator 302 and a slip ring rotor 304.

[0066] Among them, the slip ring rotor 304, the light-transmitting shaft 4, the shaft system 8, the second reflector 5, the piezoelectric ceramic sheet 6, and the test object 7 are rotating components; the laser vibration meter 1, the first reflector 2, and the slip ring stator 302 are static structures.

[0067] The drive structure is motor 10.

[0068] The first reflector 2 is fixed directly above the slip ring rotor 304 at a 45° angle to the horizontal plane; the laser vibration meter 1 is fixed in the same horizontal plane as the first reflector 2.

[0069] like Figure 2The diagram shows the structure of the slip ring 3. The slip ring stator 302 is fixed to the external bracket by locking components 303 located at both ends. The slip ring stator 302 and the locking components 303 are connected by bolts. The slip ring rotor 304 is rotatably sleeved inside the slip ring stator 302. The slip ring stator 302 is provided with signal line through holes 305 arranged around its perimeter.

[0070] like Figure 3 The diagram shows the structure of the light-transmitting shaft 4, which includes a vertical shaft and a horizontal shaft in a T-shape. One end of the vertical shaft of the light-transmitting shaft 4 is fixedly connected to the slip ring rotor 304 by bolts, and a pulley 401 is provided on the outer side. The pulley 401 is connected to the light-transmitting shaft 4 by a key. A signal line through hole 402 is provided on the pulley 401 corresponding to the signal line through hole 305. A third reflector 403 is fixedly installed inside the vertical shaft of the light-transmitting shaft 4. The third reflector 403 is at a 45° angle to the horizontal plane and is connected to the light-transmitting shaft 4 by bolts. A second reflector 5 is provided outside the horizontal shaft of the light-transmitting shaft 4. The two ends of the second reflector 5 are fixed to the horizontal shaft of the light-transmitting shaft 4 by knobs. Adjusting the angle between the second reflector 5 and the horizontal direction can adjust the focusing position of the laser measuring point of the laser vibrometer 1 on the test object 7. A threaded hole 404 is opened at the other end of the vertical shaft of the light-transmitting shaft 4.

[0071] like Figure 4 The diagram shows the structure of shaft system 8. One end of shaft system 8 near the optical axis 4 is connected to the threaded hole 404 of the optical axis via screws through each of twelve circumferentially arranged positioning holes 806. The circumferential adjustment between the threaded hole 404 of the optical axis and shaft system 8 allows for adjustment of the focusing position of the laser measuring point on the test object 7. A bearing 804 is provided on the outside of shaft system 8 for fixed connection to external stationary components. A locking element 803 is also provided at the other end of shaft system 8. Signal line through holes 805 and 801 are respectively arranged circumferentially at both ends of shaft system 8 corresponding to signal line through holes 402.

[0072] like Figure 5 The diagram shows the arrangement of the test object and piezoelectric ceramic sheet (sensor) in the LDV self-following modal experimental device with rotating structure of the present invention. The test object 7 is provided with a test object threaded hole 701, which is bolted to the locking member 803. The shaft system 8 is connected to the test object 7 at one end, and the signal line is provided with a shaft system groove 802 through the hole 801. The test object 7 is provided with a test object groove 702 corresponding to the shaft system groove 802, which communicates with the piezoelectric ceramic sheet 6.

[0073] The piezoelectric ceramic sheets 6 are arranged in a row on the test object 7; the test object 7 is connected to the PZT 6 by adhesive.

[0074] The first reflector, the second reflector 5, and the third reflector 403 are used to control the laser emitted by the laser vibrometer 1 and adjust the focusing position of the laser test object 7.

[0075] The pulley 401 is connected to the motor 10 via belt drive, thereby driving the light shaft 4 to rotate and in turn driving the slip ring rotor 304, shaft system 8, and test object 7 to rotate.

[0076] The signal line 301 passes through signal line through hole 1 305, then through signal line through hole 2 402, then through signal line through hole 3 805 into the shaft system 8, and then exits through signal line through hole 4 801, fitting into the shaft system groove 802 and the test object groove 702 to connect the piezoelectric ceramic sheet 6.

[0077] Signal lines 301 are connected one-to-one with piezoelectric ceramic sheets 6; there are at least two sets of both signal lines 301 and piezoelectric ceramic sheets 6.

[0078] In this embodiment of the invention, the mode shape of the rotating structure is measured by changing the laser focusing point multiple times.

[0079] The working principle of this invention is as follows:

[0080] During modal testing, the drive structure drives the optical shaft 4 to rotate, which in turn drives the slip ring rotor 302, the shaft system 8, and the test object 7 to rotate.

[0081] Under rotating conditions, one or more groups of signal lines 301 connected to external signal sources transmit external voltage signals to the corresponding piezoelectric ceramic sheets 6. The corresponding group of piezoelectric ceramic sheets 6 applies excitation to the test object 7, causing it to generate vibration signals. The remaining groups of piezoelectric ceramic sheets 6 serve as data acquisition units, transmitting data to the signal acquisition card via the corresponding remaining groups of signal lines 301. This data is used to analyze the vibration signals of the test object 7 to obtain the natural frequency and damping of the test object 7.

[0082] Meanwhile, the laser from the laser vibrometer 1 passes through the slip ring 3 and the optical axis 4, and is reflected by the second reflector 5 and the third reflector 403, and is focused onto the surface of the test object 7. The laser is then transmitted to the signal acquisition card for analysis of the vibration mode of the test object 7.

[0083] like Figure 6 The diagram shown is a schematic diagram of the measurement point arrangement principle applicable to extracting mode vibration modes containing 6 or fewer nodal diameters and 4 or fewer nodal circles in the LDV self-following modal experimental device of the rotating structure of the present invention.

[0084] To measure the mode shapes of a test object 7 with radius r containing n nodal diameters (diameters where the vibration amplitude is 0), several measuring points are arranged on at least n diameters on the surface of the test object 7, ensuring that at least one measuring point is located as close as possible to the outer edge of the test object 7. By extracting the imaginary part amplitude of the frequency response function corresponding to the forward traveling wave (low-frequency) mode or the backward traveling wave (high-frequency) mode at each measuring point, the mode shapes in which the test object 7 splits into forward and backward traveling waves under the n nodal diameter modes can be obtained. To avoid the measuring points being located exactly on the nodal diameters, the positions of the n diameters where the measuring points need to be placed are selected using a trial-and-error method.

[0085] In order to measure the mode shape of the test object 7 with radius r containing s (s≥1) nodal circles (concentric circles where the vibration amplitude is 0), a number of measuring points should be arranged as evenly as possible on at least s+1 concentric circles, and the radius of the s+1th concentric circle should be ri=r / s.

[0086] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0087] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rotating LDV self-following modal experimental device, characterized in that, Including static structures, rotating structures, and driving structures. The rotating structure rotates under the drive of the driving structure; The static structure includes a laser vibrometer (1) and a slip ring stator (302); The rotating structure includes a slip ring rotor (304), a light-transmitting shaft (4), a shaft system (8), a second reflector (5), a piezoelectric ceramic sheet (6), and a test object (7); the light-transmitting shaft (4) includes a vertical shaft and a horizontal shaft; The slip ring stator (302) is fixed on the bracket, and the slip ring rotor (304) is rotatably sleeved inside the slip ring stator (302); One end of the vertical shaft of the light-transmitting shaft (4) is fixedly connected to the slip ring rotor (304), and the other end is fixedly connected to one end of the shaft system (8); the other end of the shaft system (8) is fixedly connected to the test object (7); The piezoelectric ceramic sheet (6) is arranged in a circumferential pattern on the test object (7); The light transmission shaft (4) is connected to a drive structure on the outside of its vertical axis. The drive structure drives the light transmission shaft (4) to rotate, thereby causing the shaft system (8) to rotate. The light transmission axis (4) is equipped with a third reflector (403) inside the vertical axis and a second reflector (5) outside the horizontal axis of the light transmission axis (4); The two ends of the second reflector (5) are rotated and fixed on the horizontal axis of the light transmission axis (4). Adjust the angle between the second reflector (5) and the horizontal direction, and adjust the focusing position of the laser measuring point of the laser vibrometer (1) on the test object (7). The optical axis (4) and the axis system (8) can rotate circumferentially to adjust the focusing position of the laser measuring point on the test object (7); The signal line (301) is connected to the piezoelectric ceramic sheet (6) one by one; The second reflector (5) and the third reflector (403) are used to control the laser emitted by the laser vibrometer (1) and adjust the focusing position of the laser test object (7); The experimental setup is used to determine the natural frequency, damping, and mode shape of the test object (7).

2. The LDV self-following modal experimental device with a rotating structure according to claim 1, characterized in that, The stationary structure also includes a first reflector (2), which is fixed directly above the slip ring rotor (304) at an angle of (45)° to the horizontal plane; The laser vibration meter (1) is fixed in the same horizontal plane as the first reflector (2).

3. The LDV self-following modal experimental device with a rotating structure according to claim 1, characterized in that, The slip ring stator (302) is provided with a signal line through hole (305) through the circumference; The outer side of the light-transmitting axis (4) is provided with signal line through hole two (402) around the signal line through hole one (305); The two ends of the shaft system (8) are respectively provided with signal line through hole three (805) and signal line through hole four (801) corresponding to signal line through hole two (402); The shaft system (8) is connected to the test object (7) at one end, and a shaft system groove (802) is provided at the corresponding signal line through hole four (801); the test object (7) is provided with a test object groove (702) corresponding to the shaft system groove (802) to connect to the piezoelectric ceramic sheet (6); The signal line (301) enters the shaft system (8) through the signal line through hole one (305), then through the signal line through hole two (402), then through the signal line through hole three (805), and then exits through the signal line through hole four (801), fitting into the shaft system groove (802) and the test object groove (702) to connect the piezoelectric ceramic sheet (6).

4. The LDV self-following modal experimental device with a rotating structure according to claim 1, characterized in that, The piezoelectric ceramic sheet (6) is connected to the test object (7) with glue.

5. The LDV self-following modal experimental device with a rotating structure according to claim 1, characterized in that, The light-transmitting shaft (4) and the slip ring rotor (304) are connected by a nut.

6. The LDV self-following modal experimental device with a rotating structure according to claim 1, characterized in that, The vertical shaft of the light-transmitting shaft (4) is connected to the shaft system (8) at one end with a light-transmitting shaft threaded hole (404). The shaft system (8) is provided with a plurality of positioning holes (806) corresponding to the light-transmitting shaft threaded hole (404) in the circumferential direction. The light-transmitting shaft threaded hole (404) can be connected to each of the positioning holes (806) by screws to realize the circumferential adjustment of the laser measuring point of the laser vibrometer (1) on the surface (7) of the test object.

7. The LDV self-following modal experimental device with a rotating structure according to claim 1, characterized in that, The driving structure is a motor (10); The light-transmitting shaft (4) is keyed to the outer side in the vertical direction with a pulley (401); The motor (10) is connected to the pulley (401) via belt drive, thereby driving the slip ring rotor (304), shaft system (8), and test object (7) to rotate.

8. The LDV self-following modal experimental device with a rotating structure according to claim 1, characterized in that, The shaft system (8) is fixedly connected to an external stationary component via bearings; The shaft system (8) is provided with a locking member (803) at one end near the test object (7), and the locking member (803) is connected to the test object (7) by bolts.

9. A method for experimental testing of LDV self-following modes with a rotating structure, using the experimental apparatus for experimental testing of LDV self-following modes with a rotating structure as described in any one of claims 1-8, characterized in that, The method is as follows: When conducting modal experiments, the drive structure drives the light-transmitting shaft (4) to rotate, which in turn drives the slip ring rotor (302), shaft system (8) and test object (7) to rotate; Under rotating conditions, one or more groups of signal lines (301) connected to external signal sources transmit external voltage signals to the corresponding piezoelectric ceramic sheets (6). The corresponding group of piezoelectric ceramic sheets (6) applies excitation to the test object (7), causing it to generate vibration signals. The remaining groups of piezoelectric ceramic sheets (6) serve as data acquisition units, transmitting data to the signal acquisition card via the corresponding remaining groups of signal lines (301) for analyzing the vibration signals of the test object (7) to obtain the natural frequency and damping of the test object (7). Meanwhile, the laser from the laser vibrometer (1) passes through the slip ring (3) and the optical axis (4) in sequence, and is reflected by the second reflector (5) and the third reflector (403) to be focused onto the surface of the test object (7) and transmitted to the signal acquisition card for analysis of the vibration mode of the test object (7); Specifically, by arranging several measuring points on n diameters on the surface of the test object (7), with at least one measuring point near the outer edge of the test object (7), the imaginary part amplitude of the frequency response function corresponding to the forward traveling wave mode or the backward traveling wave mode of each measuring point is extracted, and the vibration modes of the test object (7) split into forward and backward traveling waves under the n-diameter mode are obtained.

10. The method according to claim 9, characterized in that, The positions of the n diameters where the measuring points need to be placed are selected by trial and error, so as to avoid the diameter where the measuring point is located on the nodal diameter; The test object (7) with radius r is measured to have s (s≥1) mode shapes with nodal circles. Several measuring points are evenly arranged on at least s+1 concentric circles, and the radius of the s+1th concentric circle is ri=r / s.

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