LDV self-following modal experiment device of rotating structure and experiment method

Abstract

The invention relates to the technical field of structural vibration dynamics experiments, in particular to an LDV self-following modal experiment device of a rotating structure and an experiment method.The experiment device comprises a static structure, the rotating structure and a driving structure, and the static structure comprises a laser vibration meter and a slip ring stator; the rotating structure comprises a slip ring rotor, a light transmission shaft, a shaft system, a second reflective mirror, a piezoelectric ceramic piece and a test object, and the light transmission shaft is further provided with a third reflective mirror; the piezoelectric ceramic piece is mounted on a test object; one or more groups of piezoelectric ceramic pieces are used for applying excitation to a test object, and the rest groups of piezoelectric ceramic pieces and the laser vibration meter are used for collecting vibration signals of the test object; the first reflector, the second reflector and the third reflector are used for controlling laser emitted by the laser vibration meter together so that the laser can be focused on a test object, and circumferential adjustment of the focusing position of the laser on the test object can be achieved through the optical axis and the shaft system. According to the LDV self-following modal experimental device and experimental method of the rotating structure, the problem that modal experiments are difficult to carry out on an existing rotating mechanical structure under the rotating working condition is solved.

Description

Technical Field

[0001] The invention relates to the technical field of structural vibration dynamics experiments, and in particular to an LDV self-following modal experimental device and an experimental method for a rotating structure. Background Art

[0002] In order to adapt to the increasing fluctuation of grid load caused by the increasing proportion of intermittent renewable energy, it is necessary to further develop variable speed pumped storage technology. Frequent variable speed operation will bring pressure pulsation in a wider frequency range, resulting in an increased risk of rotor resonance.

[0003] In the prior art, modal experiments on rotating structures such as impellers are often carried out under static conditions. Relevant studies have shown that when the impeller rotates in water, its vibration mode will split into forward waves (in the same direction as the rotation direction) and backward waves (opposite to the rotation direction), and the natural frequency of the former decreases with the increase of the rotation speed, while the latter is vice versa. In addition, the modal parameters such as vibration type and damping will also change. This increases the difficulty of resonance prediction and brings great challenges to the design and operation of variable-speed pump-turbine pumped-storage units. The variation law of modal parameters of underwater rotating structures and the fluid-solid coupling mechanism still need to be studied. In view of this, there is an urgent need for an LDV self-following modal experimental device for rotating structures to solve the above problems. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an LDV self-following modal experimental device and experimental method for a rotating structure, which can extract the modal parameters such as the natural frequency, modal damping, modal vibration shape, etc. of the test object in the air or water, so as to solve the problem of difficulty in modal experiments of underwater rotating structures carried out in the prior art.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A LDV self-following modal experimental device for a rotating structure, comprising a stationary structure, a rotating structure, and a driving structure.

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

[0008] The stationary 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 axis 4, a shaft system 8, a second reflector 5, a piezoelectric ceramic sheet 6 and a test object 7; the light-transmitting axis 4 includes a vertical axis and a horizontal axis;

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

[0011] One end of the vertical axis of the light-transmitting axis 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 6 are arranged in a circle on the test object 7;

[0013] The outer side of the vertical axis of the light-transmitting axis 4 is connected to a driving structure, and the driving structure drives the light-transmitting axis 4 to rotate and then drives the shaft system 8 to rotate;

[0014] A third reflector 403 is disposed inside the vertical axis of the light-through axis 4, and a second reflector 5 is disposed outside the horizontal axis of the light-through axis 4;

[0015] The two ends of the second reflector 5 are rotatably fixed on the horizontal axis of the light-transmitting axis 4, and the angle between the second reflector 5 and the horizontal direction is adjusted 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 focus position of the laser measuring point on the test object 7;

[0017] The signal lines 301 are connected to the piezoelectric ceramic sheets 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 focus position of the laser test object 7;

[0019] The experimental device is used to measure the natural frequency, damping and vibration mode of the test object 7.

[0020] Preferably,

[0021] The stationary structure further includes a first reflector 2, which is fixed directly above the slip ring rotor 304 and forms an angle of 45° with the horizontal plane;

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

[0023] Preferably,

[0024] The slip ring stator 302 is provided with a signal line through hole 1 305 throughout the circumference;

[0025] The outer side of the light-through axis 4 is provided with signal line through holes 402 in a row corresponding to the signal line through hole 1 305;

[0026] The two ends of the shaft system 8 are respectively provided with a signal line through hole 3 805 and a signal line through hole 4 801 corresponding to the signal line through hole 2 402;

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

[0028] The signal line 301 passes through the signal line through hole 1 305, then through the signal line through hole 2 402, and then through the signal line through hole 3 805 to enter the shaft system 8, and then is connected through the signal line through hole 4 801, and is embedded in the shaft system groove 802 and the test object groove 702 to connect the piezoelectric ceramic piece 6.

[0029] Preferably,

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

[0031] Preferably,

[0032] The light-transmitting shaft 4 is connected to the slip ring rotor 304 by riveting with nuts.

[0033] Preferably,

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

[0035] Preferably,

[0036] The driving structure is a motor 10;

[0037] The outer side key of the light-transmitting axis 4 in the vertical direction is connected with a pulley 401;

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

[0039] Preferably,

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

[0041] A locking member 803 is disposed at one end of the shaft system 8 close to the test object 7 , and the locking member 803 is connected to the test object 7 via bolts.

[0042] A LDV self-following modal test method for a rotating structure, using the LDV self-following modal test device for a rotating structure, the method specifically comprises:

[0043] When the modal experiment is carried out, the driving structure drives the light-transmitting shaft 4 to rotate, thereby driving the slip ring rotor 302, the shaft system 8 and the test object 7 to rotate;

[0044] Under the rotating condition, one or several groups of the signal lines 301 connected to the external signal source transmit the external voltage signal to the corresponding piezoelectric ceramic sheets 6, and the corresponding group of piezoelectric ceramic sheets 6 applies excitation to the test object 7 to generate a vibration signal; the piezoelectric ceramic sheets 6 of the remaining groups serve as data acquisition units, which are transmitted to the signal acquisition card via the corresponding signal lines 301 of the remaining groups, and are used to analyze the vibration signal of the test object 7 to obtain the natural frequency and damping of the test object 7;

[0045] At the same time, the laser of the laser vibrometer 1 passes through the slip ring 3 and the optical axis 4 in turn, and is reflected by the second reflector 5 and the third reflector 403, focused on the surface of the test object 7, and transmitted to the signal acquisition card for analyzing the vibration mode of the test object 7;

[0046] Specifically, a number of measuring points are arranged 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 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 to obtain the vibration mode of the test object 7 split into the forward-traveling wave and the backward-traveling wave under the n-node diameter mode.

[0047] Preferably,

[0048] The positions of the n diameters where the measuring points need to be arranged are selected by trial and error to avoid the diameter where the measuring points are located on the pitch diameter;

[0049] The test object 7 with a radius of r is measured to have modal vibration shapes of s (s≥1) pitch circles, and a number of 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. .

[0050] The beneficial effects of the present invention are:

[0051] The present invention provides an LDV self-following modal experimental device and an experimental method for a rotating structure, so as to solve the problem of difficulty in modal experiments of underwater rotating structures carried out in the prior art. On the basis of modal experiments of rotating structures in water or in high-density fluids, the variation law of modal parameters such as natural frequency, damping, vibration mode, etc. of the rotating structure with the rotation speed when the rotating structure is running in the fluid is clarified, so as to provide a reference for the development of structural dynamics theory; at the same time, it can provide a reference for the design of water pump impellers, turbine impellers, ship propellers, bearings immersed in high-density media, etc.; in addition, it can also provide a reference for the variable speed operation of variable speed pumped storage units, so as to avoid resonance when the units are running at a specific rotation speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

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

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

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

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

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

[0058] Figure 6 It is a schematic diagram of the measurement point arrangement principle suitable for extracting the modal vibration shapes containing 6 or less pitch diameters and 4 or less pitch circles in the LDV self-following modal experimental device of the rotating structure of the present invention;

[0059] Reference numerals:

[0060] 1 Laser vibrometer (LDV), 2 No. 1 reflector, 3 slip ring, 4 optical axis, 5 No. 2 reflector, 6 piezoelectric ceramic (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 No. 3 reflector, 404 optical axis threaded hole, 405 knob, 801 signal line through hole 4, 802 shaft system slot, 803 locking component, 804 bearing, 805 signal line through hole 3, 806 positioning hole, 701 test object threaded hole, 702 test object slot. DETAILED DESCRIPTION

[0061] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the following embodiments are provided only for the purpose of illustration and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0062] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0064] Combine the following Figures 1 to 6 The present invention describes an LDV self-following modal experimental device for a rotating structure.

[0065] like Figures 1 to 6 As shown, the present invention provides an LDV self-following modal experimental device for a rotating structure, which is used to collect vibration signals in a stationary coordinate system and a rotating coordinate system, and 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 driving 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 optical axis 4, the shaft system 8, the second reflector 5, the piezoelectric ceramic piece 6 and the test object 7 are rotating parts; the laser vibrometer 1, the first reflector 2 and the slip ring stator 302 are stationary structures.

[0067] The driving structure is a motor 10 .

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

[0069] like Figure 2As shown, it is a schematic diagram of the structure of the slip ring 3, the slip ring stator 302 is fixed to the external bracket through the locking components 303 arranged at both ends thereof, the slip ring stator 302 and the locking components 303 are connected by bolts, and the slip ring rotor 304 is rotatably penetrated and sleeved in the slip ring stator 302; the slip ring stator 302 is provided with a signal line through hole 305 arranged around it.

[0070] like Figure 3 As shown, it is a schematic diagram of the structure of the optical axis 4, including a vertical axis and a horizontal axis, which are T-shaped. One end of the vertical axis of the optical axis 4 is fixedly connected to the slip ring rotor 304 by bolt riveting, and a pulley 401 is arranged on the outside; the pulley 401 and the optical axis 4 are connected by a key; the pulley 401 is provided with a signal line through hole 2 402 corresponding to the signal line through hole 1 305; a third reflector 403 is fixedly arranged in the vertical axis of the optical axis 4, and the third reflector 403 is at an angle of 45° to the horizontal plane, and the third reflector 403 is connected to the optical axis 4 by bolts; a second reflector 5 is arranged outside the horizontal axis of the optical axis 4; the two ends of the second reflector 5 are fixed to the horizontal axis of the optical axis 4 by a knob, and the angle between the second reflector 5 and the horizontal direction can be adjusted to adjust the focusing position of the laser measuring point of the laser vibrometer 1 on the test object 7. A threaded hole 404 of the optical axis is opened at the other end of the vertical axis of the optical axis 4.

[0071] like Figure 4 As shown in the figure, it is a schematic diagram of the structure of the shaft system 8. Each of the twelve positioning holes 806 arranged in a circle at one end of the shaft system 8 near the light-transmitting axis 4 can be connected to the light-transmitting axis threaded hole 404 through a screw. The light-transmitting axis threaded hole 404 and the shaft system 8 can be adjusted in a circumferential direction to adjust the focus position of the laser measuring point on the test object 7. A bearing 804 is provided on the outside of the shaft system 8 to be fixedly connected to an external stationary part. A locking member 803 is also provided at the other end of the shaft system 8. Signal line through hole 3 805 and signal line through hole 4 801 are arranged in a circle at both ends of the shaft system 8 corresponding to the signal line through hole 2 402.

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

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

[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 focus position of the laser test object 7 .

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

[0076] The signal line 301 passes through the signal line through hole 1 305, then through the signal line through hole 2 402, and then through the signal line through hole 3 805 to enter the shaft system 8, and then is connected through the signal line through hole 4 801, and is embedded in the shaft system groove 802 and the test object groove 702 to connect the piezoelectric ceramic piece 6.

[0077] The signal lines 301 are connected to the piezoelectric ceramic sheets 6 in a one-to-one correspondence; the number of the signal lines 301 and the piezoelectric ceramic sheets 6 is no less than 2 groups.

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

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

[0080] When carrying out the modal experiment, the driving structure drives the light-transmitting shaft 4 to rotate, thereby driving the slip ring rotor 302, the shaft system 8 and the test object 7 to rotate.

[0081] Under the rotating condition, one or several groups of the signal lines 301 connected to the external signal source transmit the external voltage signal to the corresponding piezoelectric ceramic pieces 6, and the corresponding group of piezoelectric ceramic pieces 6 applies excitation to the test object 7 to generate a vibration signal; the piezoelectric ceramic pieces 6 in the remaining groups serve as data acquisition units, which are transmitted to the signal acquisition card via the corresponding signal lines 301 of the remaining groups, and are used to analyze the vibration signal of the test object 7 to obtain the natural frequency and damping of the test object 7.

[0082] At the same time, the laser of the laser vibrometer 1 passes through the slip ring 3 and the optical axis 4 in turn, is reflected by the second reflector 5 and the third reflector 403, focused on the surface of the test object 7, and transmitted to the signal acquisition card for analyzing the vibration mode of the test object 7.

[0083] like Figure 6 , which is a schematic diagram of the measurement point arrangement principle suitable for extracting modal vibration shapes containing 6 or less pitch diameters and 4 or less pitch circles in the LDV self-following modal experimental device of the rotating structure of the present invention.

[0084] In order to measure the modal vibration shape of the test object 7 with radius r and containing n node diameters (the diameter where the vibration amplitude is 0), several measuring points are arranged on at least n diameters on the surface of the test object 7, and it must be ensured that there is at least one measuring point as close to the outer edge as possible. By extracting the imaginary amplitude of the frequency response function corresponding to the forward wave (low frequency) mode or the backward wave (high frequency) mode of each measuring point, the vibration shape of the test object 7 split into the forward wave and the backward wave under the n node diameter mode can be obtained. In order to avoid the diameter where the measuring point is located exactly on the node diameter, the positions of the n diameters where the measuring points need to be arranged are selected by trial and error.

[0085] In order to measure the modal vibration shape of the test object 7 with a radius of r containing s (s≥1) node 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 belong to the prior art known to professional and technical personnel in this field.

[0087] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An LDV self-following modal experimental device for a rotating structure, characterized in that: Including stationary structure, rotating structure, driving structure, The rotating structure rotates under the driving of the driving structure; The stationary structure comprises a laser vibrometer (1) and a slip ring stator (302); The rotating structure comprises a slip ring rotor (304), a light-transmitting axis (4), an axis system (8), a second reflector (5), a piezoelectric ceramic sheet (6) and a test object (7); the light-transmitting axis (4) comprises a vertical axis and a horizontal axis; The slip ring stator (302) is fixed on a bracket, and the slip ring rotor (304) is rotatably inserted through the slip ring stator (302); One end of the vertical axis of the light-transmitting axis (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 sheets (6) are distributed in a circumferential manner on the test object (7); The outer side of the vertical axis of the light-transmitting axis (4) is connected to a driving structure, and the driving structure drives the light-transmitting axis (4) to rotate, thereby driving the shaft system (8) to rotate; A third reflector (403) is disposed inside the vertical axis of the light-transmitting axis (4), and a second reflector (5) is disposed outside the horizontal axis of the light-transmitting axis (4); The two ends of the second reflector (5) are rotatably fixed on the horizontal axis of the light transmission axis (4), and the angle between the second reflector (5) and the horizontal direction is adjusted to adjust the focus 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 focus position of the laser measuring point on the test object (7); The signal lines (301) are connected to the piezoelectric ceramic sheets (6) in a one-to-one correspondence; The second reflector (5) and the third reflector (403) are used to control the laser emitted by the laser vibrometer (1) and adjust the focus position of the laser test object (7); The experimental device is used to measure the natural frequency, damping and vibration mode of the test object (7).

2. The LDV self-following modal experimental device of a rotating structure according to claim 1, characterized in that: The stationary structure further comprises a first reflector (2), wherein the first reflector (2) is fixed directly above the slip ring rotor (304) and is at an angle of (45)° to the horizontal plane; The laser vibrometer (1) is fixed in the same horizontal plane as the first reflector (2).

3. The LDV self-following modal experimental device of a rotating structure according to claim 1, characterized in that: The slip ring stator (302) is provided with a signal line through hole (305) running through the periphery; Signal line through holes (402) are arranged on the outside of the light-through axis (4) in a circle corresponding to the signal line through hole (305); The two ends of the shaft system (8) are respectively provided with a signal line through hole three (805) and a signal line through hole four (801) corresponding to the signal line through hole two (402); The shaft system (8) is connected to the test object (7) at one end thereof and is provided with a shaft system groove (802) corresponding to the signal line through hole 4 (801); the test object (7) is provided with a test object groove (702) corresponding to the shaft system groove (802) and is connected to the piezoelectric ceramic sheet (6); The signal line (301) passes through the signal line through hole one (305), then through the signal line through hole two (402), and then through the signal line through hole three (805) to enter the interior of the shaft system (8), and then through the signal line through hole four (801) to be connected to the piezoelectric ceramic sheet (6) by being embedded in the shaft system groove (802) and the test object groove (702).

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

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

6. The LDV self-following modal experimental device of a rotating structure according to claim 1, characterized in that: A through-light axis threaded hole (404) is provided at one end of the vertical axis of the through-light axis (4) connected to the shaft system (8); a plurality of positioning holes (806) corresponding to the through-light axis threaded hole (404) are circumferentially arranged on the shaft system (8); the through-light axis threaded hole (404) can be connected to each of the positioning holes (806) by means of screws, thereby achieving 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 of a rotating structure according to claim 1, characterized in that: The driving structure is a motor (10); The outer side key of the light-transmitting axis (4) in the vertical direction is connected with a pulley (401); The motor (10) is connected to the pulley (401) via a belt drive, thereby driving the slip ring rotor (304), the shaft system (8), and the test object (7) to rotate.

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

9. A LDV self-following modal test method for a rotating structure, using the LDV self-following modal test device for a rotating structure according to any one of claims 1 to 8, characterized in that: The method is as follows: When carrying out a modal experiment, the driving structure drives the light-transmitting shaft (4) to rotate, thereby driving the slip ring rotor (302), the shaft system (8) and the test object (7) to rotate; Under the rotating working condition, one or more groups of the signal lines (301) connected to the external signal source transmit the external voltage signal to the corresponding piezoelectric ceramic sheets (6), and the corresponding group of piezoelectric ceramic sheets (6) applies excitation to the test object (7) to generate a vibration signal; the remaining groups of piezoelectric ceramic sheets (6) serve as data acquisition units, which are transmitted to the signal acquisition card via the corresponding signal lines (301) of the remaining groups, and are used to analyze the vibration signal of the test object (7) to obtain the natural frequency and damping of the test object (7); At the same time, the laser of the laser vibrometer (1) passes through the slip ring (3) and the optical axis (4) in turn, is reflected by the second reflector (5) and the third reflector (403), is focused on the surface of the test object (7), and is transmitted to the signal acquisition card for analyzing the vibration mode of the test object (7); Specifically, a plurality of measuring points are arranged on n diameters on the surface of the test object (7), with at least one measuring point being located near the outer edge of the test object (7); the imaginary 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 mode of the test object (7) split into the forward-traveling wave and the backward-traveling wave under the n-node diameter mode is obtained.

10. The method according to claim 9, characterized in that The positions of the n diameters where the measuring points need to be arranged are selected by trial and error to avoid the diameter where the measuring points are located on the pitch diameter; The test object (7) with a radius of r is measured to have modal vibration shapes of s (s≥1) pitch circles, and a number of 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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