A biaxial fatigue loading control method and loading device for fan blades

Abstract

The present invention relates to a biaxial fatigue loading control method and loading device for fan blades. The control method includes the following steps: S1: applying an initial swing excitation of a certain amplitude to the fan blades in the horizontal direction using an inertial vibrator, and applying an initial flapping excitation of a certain amplitude to the fan blades in the vertical direction using a direct-drive vibrator, so that the fan blades produce a dynamic response; S2: collecting the dynamic response of the fan blades during motion; S3: obtaining resonant excitation in the swing and flapping directions based on the dynamic response of the fan blades during motion, controlling the excitation of the inertial vibrator based on the resonant excitation in the swing direction, and controlling the excitation of the direct-drive vibrator based on the resonant excitation in the flapping direction, so that the dynamic response of the fan blades during motion is consistent with the target response of the fan blades. Compared with the prior art, the present invention effectively saves the total energy consumption of biaxial loading and improves the degree of automation of biaxial fatigue testing.

Description

Technical Field

[0001] The present invention relates to the field of fatigue testing of fan blades, and in particular to a biaxial fatigue loading control method and loading equipment for fan blades. Background Art

[0002] Wind turbine blades are key components of wind turbines. During operation, they withstand significant wind loads for extended periods, making their safe operation within their designed fatigue life crucial. Blade fatigue testing is a crucial component of blade design, finalization, and production. This test simulates a 20-year blade lifespan and verifies the rationality of the blade's structure, layup, and bonding designs. It can also identify manufacturing defects during the manufacturing process and verify that the blade's design and manufacturing meet requirements.

[0003] During blade fatigue testing, the blades are subjected to millions of fatigue vibrations in both the flapping and shimmying directions, with the vibration frequency corresponding to the first-order natural frequency in each direction. To accommodate the growing trend in the production of large and ultra-large offshore wind turbine blades, biaxial fatigue loading methods are gaining increasing attention. Biaxial testing involves simultaneous fatigue vibration of the blades in both the flapping and shimmying directions. This biaxial loading mode applies excitation forces to the blades simultaneously, significantly reducing test duration and providing a more realistic equivalent wind load, more consistent with blade damage evolution.

[0004] However, when fatigue loads are applied to the blade in both the flapping and shimmying directions and blade performance is measured, the exciting forces in the flapping direction and the shimmying direction affect each other, resulting in large energy loss during biaxial loading and difficulty in automated control. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a biaxial fatigue loading control method and loading equipment for fan blades, thereby saving energy loss during the biaxial loading process.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for controlling biaxial fatigue loading of fan blades comprises the following steps:

[0008] S1: applying an initial swing excitation of a certain amplitude to the fan blades in the horizontal direction using an inertial vibrator, and applying an initial flapping excitation of a certain amplitude to the fan blades in the vertical direction using a direct-drive vibrator, so that the fan blades generate a dynamic response;

[0009] S2: collecting the dynamic response of the fan blade during movement;

[0010] S3: Obtain resonant excitations in the swing direction and the flapping direction based on the dynamic response of the fan blade during movement, control the excitation of the inertial vibrator based on the resonant excitation in the swing direction, and control the excitation of the direct-drive vibrator based on the resonant excitation in the flapping direction, so that the dynamic response of the fan blade during movement is consistent with the target response of the fan blade.

[0011] In one embodiment, in step S3, the dynamic response of the fan blade during movement is decomposed by a decoupling method to obtain a shimmy response component and a flapping response component;

[0012] Obtaining a resonant excitation in a swing direction based on the swing response component, and controlling an excitation frequency and an excitation phase of the inertial exciter based on the resonant excitation in the swing direction so that the swing response component of the fan blade during movement is consistent with a swing target response of the fan blade;

[0013] A resonant excitation in a flapping direction is obtained based on the flapping response component, and an excitation frequency and an excitation phase of the direct-drive vibrator are controlled based on the resonant excitation in the flapping direction, so that the flapping response component of the fan blade during movement is consistent with the flapping target response of the fan blade.

[0014] In one embodiment, after step S3, the following steps are further included:

[0015] S4: Decompose the dynamic response of the fan blade during movement by a decoupling method to obtain a swing response component and a flapping response component; obtain the phase difference between the swing direction and the flapping direction based on the swing response component and the flapping response component, and adjust the phase of the inertial exciter or the phase of the direct-drive exciter based on the phase difference so that the biaxial motion trajectory of the fan blade is consistent with the target biaxial motion trajectory of the fan blade.

[0016] In one embodiment, in step S1 , the direct-drive exciter applies excitation when the flapping response component reaches a maximum value.

[0017] In one embodiment, in step S4, the decoupling method includes a frequency domain analysis method and a bandpass filtering method.

[0018] In one embodiment, before step S1, the following steps are further included:

[0019] S0: Obtain the swing natural frequency and flapping natural frequency of the fan blade according to the physical parameters of the fan blade and the mass of the inertial vibrator, select the swing natural frequency as the frequency of the initial swing excitation, and select the flapping natural frequency as the frequency of the initial flapping excitation.

[0020] In one embodiment, in step S0, the physical parameters of the fan blade include: equivalent mass of the fan blade, equivalent stiffness of the fan blade in the swing direction, and equivalent stiffness of the fan blade in the flapping direction;

[0021] The calculation formula of the shimmy natural frequency is as follows:

[0022]

[0023] The calculation formula of the flapping natural frequency is as follows:

[0024]

[0025] Among them, w e is the natural frequency of oscillation, k e is the equivalent stiffness of the fan blade in the swing direction, w f is the natural frequency of flapping, k f is the equivalent stiffness of the fan blade in the flapping direction, m is the equivalent mass of the fan blade, and m′ is the mass of the inertial exciter.

[0026] In one embodiment, in step S2, the dynamic response of the wind turbine blade during movement is collected by strain gauges or distance measuring instruments, and the strain gauges are set at the main beam positions of the PS surface and SS surface of the blade, as well as the leading and trailing edge positions.

[0027] In one embodiment, in step S1, the inertial vibrator adopts an eccentric swing arm vibrator or a reciprocating vibrator, and the inertial vibrator applies simple harmonic excitation to the wind turbine blades. The direct-drive vibrator adopts a traction vibrator, and the direct-drive vibrator applies periodic excitation to the wind turbine blades.

[0028] A biaxial fatigue loading device for a fan blade, used to execute the biaxial fatigue loading control method for a fan blade, comprising:

[0029] A clamp, wherein the clamp is clamped on the outer side of the fan blade, and the rotation plane of the fan blade is parallel to the horizontal direction;

[0030] an inertial vibration exciter, the inertial vibration exciter being provided on the fixture and being used to apply oscillatory excitation to the fan blades in a horizontal direction;

[0031] a direct-drive vibrator connected to the fixture and configured to apply flapping excitation to the fan blades in a vertical direction;

[0032] a response detection unit, the response detection unit being provided on the fan blade and being used for detecting the dynamic response of the fan blade in real time;

[0033] A control unit is connected to the inertial vibrator, the direct-drive vibrator, and the response detection unit, respectively, and is used to control the swing excitation of the inertial vibrator and the flapping excitation of the direct-drive vibrator according to the dynamic response of the response detection unit.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. The aforementioned biaxial fatigue loading control method for wind turbine blades, under biaxial loading conditions, first applies swing excitation to the wind turbine blades in the horizontal direction using an inertial vibrator. The inertial vibrator can be directly mounted on a fixture, eliminating the need for additional brackets and resulting in a simple structure. Secondly, a direct-drive vibrator applies flapping excitation to the wind turbine blades in the vertical direction, eliminating the need for additional energy to overcome deadweight. This compensates for the inertial vibrator's shortcomings in flapping loading, resulting in low power loss and effectively saving the total energy consumption of biaxial loading. Simultaneously, resonant excitation in both the swing and flapping directions is obtained based on the dynamic response of the wind turbine blades during motion. The excitation of the inertial vibrator and the direct-drive vibrator is then controlled, achieving closed-loop loading for both swing and flapping excitations. This allows for tracking the blade's resonant frequency, ensuring the blade remains in a resonant state and improving the automation of biaxial fatigue testing.

[0036] 2. By decoupling the dynamic response, the swing response component and the flapping response component can be obtained. Not only can the excitation frequency and phase of the inertial exciter in the swing direction and the excitation frequency and phase of the direct-drive exciter in the flapping direction be controlled separately, but the phase difference between the swing direction and the flapping direction can also be controlled to ensure that flapping excitation is performed when the flapping response component reaches its maximum value, thereby minimizing the output power of the direct-drive exciter.

[0037] 3. The inertial vibrator can be used as a counterweight to compensate for the mass in the flapping and shimmying directions, thereby adjusting the natural frequency of the blade flapping and shimmying. No additional mass compensation mechanism is required, effectively simplifying the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The figure is a flow chart of the biaxial fatigue loading control method for fan blades in the present invention.

[0039] Figure 2 It is a structural schematic diagram of the biaxial fatigue loading device for wind turbine blades in the present invention.

[0040] Figure 3 It is a schematic diagram illustrating parameters of parts on the cross section of the fan blade in the present invention.

[0041] Reference numerals: 100, biaxial fatigue loading device for wind turbine blades; 10, wind turbine blades; 20, inertial exciter; 30, direct-drive exciter; 40, response detection unit; 50, control unit. DETAILED DESCRIPTION

[0042] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0043] like Figure 1 As shown, in one embodiment, a method for controlling biaxial fatigue loading of a fan blade is provided, comprising the following steps:

[0044] S1: applying an initial swing excitation of a certain amplitude to the fan blade 10 in the horizontal direction using an inertial exciter 20, and applying an initial flapping excitation of a certain amplitude to the fan blade 10 in the vertical direction using a direct-drive exciter 30, so that the fan blade 10 generates a dynamic response;

[0045] S2: collecting the dynamic response of the fan blade 10 during movement;

[0046] S3: Obtain the resonant excitation in the swing direction and the flapping direction according to the dynamic response of the fan blade 10 during movement, control the excitation of the inertial exciter 20 according to the resonant excitation in the swing direction, and control the excitation of the direct-drive exciter 30 according to the resonant excitation in the flapping direction, so that the dynamic response of the fan blade 10 during movement is consistent with the target response of the fan blade 10.

[0047] In a biaxial loading condition, assuming an inertial vibrator 20 is used to apply flapping excitation to the wind turbine blades 10 in the vertical direction, the inertial vibrator 20 requires additional motor power to offset the exciter's own mass. Furthermore, during the exciter's energy conversion, a portion of the energy is consumed by the braking resistor. Therefore, the inertial vibrator 20 requires a higher power rating to compensate for the additional energy consumption and achieve the desired excitation. In the swing direction, when the direct-drive vibrator 30 applies excitation in the horizontal direction, an additional fixing bracket is required to ensure the excitation direction remains horizontal, resulting in a complex structure.

[0048] Therefore, in the above-mentioned biaxial fatigue loading control method for fan blades, in the biaxial loading condition, the inertial vibrator 20 is first used to apply swing excitation to the fan blade 10 in the horizontal direction. The inertial vibrator 20 can be directly set on the fixture without the need to install an additional bracket, and the structure is simple; secondly, the direct-drive vibrator 30 is used to apply flapping excitation to the fan blade 10 in the vertical direction. No additional energy is required to overcome the deadweight, which makes up for the deficiency of the inertial vibrator 20 in loading in the flapping direction, has low power loss, and effectively saves the total energy consumption of biaxial loading.

[0049] Simultaneously, resonant excitation in the shimmy and flapping directions is obtained based on the dynamic response of the wind turbine blade 10 during motion. This in turn controls the excitation of the inertial exciter 20 and the direct-drive exciter 30, achieving closed-loop loading for both shimmy and flapping excitation. This enables blade resonant frequency tracking, ensuring the blade remains in a resonant state and improving the automation of biaxial fatigue testing.

[0050] Specifically, in one embodiment, before step S1, the fan blade biaxial fatigue loading control method further includes the following steps:

[0051] S0: Obtain the swing natural frequency and flapping natural frequency of the fan blade 10 according to the physical parameters of the fan blade 10 and the mass of the inertial vibrator 20, select the swing natural frequency as the frequency of the initial swing excitation, and select the flapping natural frequency as the frequency of the initial flapping excitation.

[0052] Furthermore, in one embodiment, in the step S0, the physical parameters of the fan blade 10 include: an equivalent mass of the fan blade, an equivalent stiffness of the fan blade 10 in a swing direction, and an equivalent stiffness of the fan blade 10 in a flapping direction;

[0053] The calculation formula of the shimmy natural frequency is as follows:

[0054]

[0055] Among them, w e is the natural frequency of oscillation, k e is the equivalent stiffness of the fan blade 10 in the swing direction, m is the equivalent mass of the fan blade, and m′ is the mass of the inertial exciter 20;

[0056] The calculation formula of the flapping natural frequency is as follows:

[0057]

[0058] Among them, w f is the natural frequency of flapping, k fis the equivalent stiffness of the fan blade 10 in the flapping direction, m is the equivalent mass of the fan blade, and m′ is the mass of the inertial exciter 20 .

[0059] In the above method, the inertial vibrator 20 can be used as a counterweight to perform mass compensation in the flapping direction and the swing direction, thereby adjusting the natural frequency of the blade flapping and swinging. No additional mass compensation mechanism is required, effectively simplifying the structure.

[0060] When performing mass compensation, an additional mass of m′ is added in the swing direction, and the first-order swing natural frequency is

[0061] The first-order swing natural frequency of the fan blade 10 is reduced. At this time, the external swing excitation frequency can also be appropriately reduced, that is, the excitation output by the inertial exciter 20 can be reduced, which is beneficial to saving the energy consumption of the inertial exciter 20. At the same time, the additional mass m' is increased in the swing direction, and the first-order swing natural frequency The first-order flapping natural frequency of the fan blade 10 is reduced, and the external flapping excitation frequency can also be appropriately reduced. That is, the excitation output by the direct-drive exciter 30 can be reduced, which is beneficial to saving energy consumption of the direct-drive exciter 30.

[0062] Specifically, in one embodiment, in step S1, the inertial vibrator 20 adopts an eccentric swing arm vibrator or a reciprocating vibrator, wherein the inertial vibrator 20 applies simple harmonic excitation to the wind turbine blade 10, and the direct-drive vibrator 30 adopts a traction vibrator, and the direct-drive vibrator 30 applies periodic excitation to the wind turbine blade 10, wherein the periodic excitation is half-wave simple harmonic excitation or square wave excitation.

[0063] Furthermore, the eccentric swing arm vibrator applies an exciting force to the fan blade 10 by driving the centrifugal action generated by the mass block. The eccentric swing arm vibrator includes a swing arm, a mass block and a frequency converter. One end of the swing arm is connected to the clamp, and the other end of the swing arm is fixed with the mass block. The frequency converter is connected to the swing arm for adjusting the vibration frequency of the swing arm. The frequency converter is electrically connected to the control unit 50 for transmitting the excitation signal.

[0064] Furthermore, the traction vibrator specifically includes a clamp, a motor, a drum, a loading cable and a pulley set. The clamp is clamped on the blade; the motor, drum, loading cable and pulley set each have two sets, the drum is connected to the output shaft of the motor, one end of the loading cable is wound on the drum, and the other end passes through its corresponding pulley set and is connected to the clamp. The two sets of combinations are connected to the clamp from the left and right sides or the top and bottom sides of the loading cable, respectively, to achieve the excitation loading of the wind turbine blade 10 by the direct-drive vibrator 30. Since the installation position of the direct-drive vibrator 30 is fixed, when the wind turbine blade 10 moves in space, the angle between the loading cable and the wind turbine blade 10 will continue to change. In order to ensure that the wind turbine blade 10 can reach the target amplitude, the direct-drive vibrator 30 can compensate and adjust the phase of the excitation applied to the wind turbine blade 10 according to the vibration trajectory of the wind turbine blade 10, so as to make up for the problem that the output excitation force direction of the direct-drive vibrator 30 is not parallel to the swinging direction caused by the swinging direction movement of the wind turbine blade 10.

[0065] Specifically, if Figure 3 As shown, in one embodiment, in step S2, the dynamic response of the wind blade 10 during movement is collected using strain gauges or a distance measuring instrument. The strain gauges are installed at the main beam positions (PS-SC and SS-SC) and leading and trailing edge positions (LE and TE) of the PS and SS surfaces of the blade. The stress changes during movement of the wind blade 10 are obtained through numerical conversion of the strain gauges. The distance measuring instrument is directly installed on the side of the blade to directly obtain the motion trajectory of the wind blade 10 during movement.

[0066] Specifically, in one embodiment, in step S3, the dynamic response of the fan blade 10 during movement is decomposed by a decoupling method to obtain a shimmy response component and a flapping response component;

[0067] Obtaining a resonant excitation in a swing direction based on the swing response component, and controlling an excitation frequency and an excitation phase of the inertial exciter 20 based on the resonant excitation in the swing direction, so that the swing response component of the fan blade 10 during movement is consistent with a swing target response of the fan blade 10;

[0068] The resonant excitation in the flapping direction is obtained based on the flapping response component, and the excitation frequency and excitation phase of the direct-drive exciter 30 are controlled based on the resonant excitation in the flapping direction, so that the flapping response component of the fan blade 10 during movement is consistent with the flapping target response of the fan blade 10.

[0069] Furthermore, in one embodiment, after step S3, the fan blade biaxial fatigue loading control method further includes the following steps:

[0070] S4: The dynamic response of the fan blade 10 during movement is decomposed by a decoupling method to obtain a swing response component and a flapping response component; the phase difference between the swing direction and the flapping direction is obtained according to the swing response component and the flapping response component, and the phase of the inertial exciter 20 or the phase of the direct-drive exciter 30 is adjusted according to the phase difference, so that the phase difference between the swing direction and the flapping direction during movement of the fan blade 10 is consistent with the target phase difference of the fan blade 10, thereby achieving the consistency between the biaxial motion trajectory of the fan blade and the target biaxial motion trajectory of the fan blade.

[0071] Wherein, in the step S1 , the direct-drive exciter 30 applies excitation when the flapping response component reaches a maximum value.

[0072] Furthermore, in step S3 and step S4, the decoupling method includes a frequency domain analysis method and a bandpass filtering method.

[0073] The above method can obtain the swing response component and the flapping response component by decoupling the dynamic response. It can not only control the excitation frequency and phase of the inertial exciter 20 in the swing direction and the excitation frequency and phase of the direct-drive exciter 30 in the flapping direction, but also control the phase difference between the swing direction and the flapping direction to ensure that the flapping excitation is performed when the flapping response component reaches its maximum value, thereby ensuring that the output power of the direct-drive exciter 30 is minimized.

[0074] like Figure 2 As shown, in one embodiment, a biaxial fatigue loading device 100 for a wind turbine blade is provided, which is used to execute the biaxial fatigue loading control method for a wind turbine blade, including:

[0075] A clamp, wherein the clamp is clamped on the outer side of the fan blade 10, and the rotation plane of the fan blade 10 is parallel to the horizontal direction;

[0076] an inertial vibration exciter 20 , which is provided on the fixture and is used to apply oscillation excitation to the fan blade 10 in a horizontal direction;

[0077] a direct-drive vibrator 30 , connected to the fixture and configured to apply flapping excitation to the wind turbine blade 10 in a vertical direction;

[0078] a response detection unit 40 , the response detection unit 40 being provided on the fan blade 10 and configured to detect a dynamic response of the fan blade 10 in real time;

[0079] A control unit 50 is connected to the inertial vibrator 20, the direct-drive vibrator 30, and the response detection unit 40, respectively, and is used to control the swing excitation of the inertial vibrator 20 and the flapping excitation of the direct-drive vibrator 30 according to the dynamic response of the response detection unit 40.

[0080] Therefore, the above-mentioned wind turbine blade biaxial fatigue loading device 100, in the biaxial loading condition, first adopts the inertial vibrator 20 to apply swing excitation to the wind turbine blade 10 in the horizontal direction. The inertial vibrator 20 can be directly set on the fixture without the need to install additional brackets, and the structure is simple; secondly, the direct-drive vibrator 30 is adopted to apply flapping excitation to the wind turbine blade 10 in the vertical direction. No additional energy is required to overcome the automatic, which makes up for the deficiency of the inertial vibrator 20 in loading in the flapping direction, has low power loss, and effectively saves the total energy consumption of biaxial loading.

[0081] At the same time, a response detection unit 40 is used to obtain the dynamic response of the fan blade 10 during movement, and a control unit 50 is used to obtain the resonant excitation in the swing direction and the flapping direction according to the dynamic response of the fan blade 10 during movement, thereby controlling the excitation of the inertial exciter 20 and the direct-drive exciter 30, thereby realizing closed-loop loading of the excitation in the swing direction and the flapping direction, thereby realizing blade resonance frequency tracking to ensure that the blade is always in a resonant state, thereby improving the degree of automation of the biaxial fatigue test.

[0082] The response detection unit 40 includes strain gauges or distance measuring instruments. The strain gauges are installed at the main beam positions on the PS and SS surfaces of the blade, as well as at the leading and trailing edges. The dynamic response of the wind turbine blade 10 during movement is obtained by converting the numerical values ​​of the strain gauges. The distance measuring instrument is installed directly on the side of the blade to directly obtain the dynamic response of the wind turbine blade 10 during movement.

[0083] In this specific embodiment, the number of inertial vibrators 20 and direct-drive vibrators 30 can be adjusted according to the required load of the blade, which can meet the multi-point biaxial loading fatigue test of full-size wind turbine blades 10 and high-frequency component testing conditions, such as blade tip testing.

[0084] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0085] S1: Controlling the inertial exciter 20 to apply an initial swing excitation of a certain amplitude to the fan blade 10 in the horizontal direction, and controlling the direct-drive exciter 30 to apply an initial flapping excitation of a certain amplitude to the fan blade 10 in the vertical direction, so that the fan blade 10 generates a dynamic response;

[0086] S2: collecting the dynamic response of the fan blade 10 during movement;

[0087] S3: Obtain the resonant excitation in the swing direction and the flapping direction according to the dynamic response of the fan blade 10 during movement, control the excitation of the inertial exciter 20 according to the resonant excitation in the swing direction, and control the excitation of the direct-drive exciter 30 according to the resonant excitation in the flapping direction, so that the dynamic response of the fan blade 10 during movement is consistent with the target response of the fan blade 10.

[0088] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0089] Throughout this specification, references to terms such as "some embodiments," "other embodiments," and "desired embodiments" indicate that a particular feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Although these terms are used interchangeably throughout this specification, they do not necessarily refer to the same embodiment or example.

[0090] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A biaxial fatigue loading control method for fan blades, characterized in that: The steps include: S0: obtaining the swing natural frequency and the flapping natural frequency of the fan blade according to the physical parameters of the fan blade and the mass of the inertial vibrator, selecting the swing natural frequency as the frequency of the initial swing excitation, and selecting the flapping natural frequency as the frequency of the initial flapping excitation; S1: applying an initial swing excitation of a certain amplitude to the fan blades in the horizontal direction using the inertial vibrator, and applying an initial flapping excitation of a certain amplitude to the fan blades in the vertical direction using the direct-drive vibrator, so that the fan blades generate a dynamic response; S2: collecting the dynamic response of the fan blade during movement; S3: obtaining resonant excitations in the swing direction and the flapping direction based on the dynamic response of the fan blade during movement, controlling the excitation of the inertial exciter based on the resonant excitation in the swing direction, and controlling the excitation of the direct-drive exciter based on the resonant excitation in the flapping direction, so that the dynamic response of the fan blade during movement is consistent with the target response of the fan blade, specifically including: Decomposing the dynamic response of the fan blade during movement by a decoupling method to obtain a shimmy response component and a flapping response component; Obtaining a resonant excitation in a swing direction based on the swing response component, and controlling an excitation frequency and an excitation phase of the inertial exciter based on the resonant excitation in the swing direction so that the swing response component of the fan blade during movement is consistent with a swing target response of the fan blade; obtaining a resonant excitation in a flapping direction based on the flapping response component, and controlling an excitation frequency and an excitation phase of the direct-drive vibrator based on the resonant excitation in the flapping direction so that the flapping response component of the fan blade during movement is consistent with a target flapping response of the fan blade; S4: Decompose the dynamic response of the fan blade during movement by a decoupling method to obtain a swing response component and a flapping response component; obtain the phase difference between the swing direction and the flapping direction based on the swing response component and the flapping response component, and adjust the phase of the inertial exciter or the phase of the direct-drive exciter based on the phase difference so that the biaxial motion trajectory of the fan blade is consistent with the target biaxial motion trajectory of the fan blade.

2. A fan blade biaxial fatigue loading control method according to claim 1, characterized in that: In step S1 , the direct-drive exciter applies excitation when the flapping response component reaches a maximum value.

3. A fan blade biaxial fatigue loading control method according to claim 1, characterized in that: In step S4, the decoupling method includes a frequency domain analysis method and a bandpass filtering method.

4. A fan blade biaxial fatigue loading control method according to claim 1, characterized in that: In the step S0, the physical parameters of the fan blade include: the equivalent mass of the fan blade, the equivalent stiffness of the fan blade in the swing direction, and the equivalent stiffness of the fan blade in the flapping direction; The calculation formula of the shimmy natural frequency is as follows: The calculation formula of the flapping natural frequency is as follows: Among them, w e is the natural frequency of oscillation, k e is the equivalent stiffness of the fan blade in the swing direction, w f is the natural frequency of flapping, k f is the equivalent stiffness of the fan blade in the flapping direction, m is the equivalent mass of the fan blade, m ′ is the mass of the inertial vibrator.

5. A fan blade biaxial fatigue loading control method according to claim 1, characterized in that: In step S2, the dynamic response of the wind turbine blade during movement is collected by strain gauges or distance measuring instruments, and the strain gauges are set at the main beam positions of the PS and SS surfaces of the blade, as well as the leading and trailing edge positions.

6. A fan blade biaxial fatigue loading control method according to claim 1, characterized in that: In step S1, the inertial vibrator adopts an eccentric swing arm vibrator or a reciprocating vibrator, and the inertial vibrator applies simple harmonic excitation to the wind turbine blades. The direct-drive vibrator adopts a traction vibrator, and the direct-drive vibrator applies periodic excitation to the wind turbine blades.

7. A biaxial fatigue loading device for fan blades, characterized in that: A method for controlling biaxial fatigue loading of a wind turbine blade according to any one of claims 1 to 6, comprising: A clamp, wherein the clamp is clamped on the outer side of the fan blade, and the rotation plane of the fan blade is parallel to the horizontal direction; an inertial vibration exciter, the inertial vibration exciter being provided on the fixture and being used to apply oscillatory excitation to the fan blades in a horizontal direction; a direct-drive vibrator connected to the fixture and configured to apply flapping excitation to the fan blades in a vertical direction; a response detection unit, the response detection unit being provided on the fan blade and being used for detecting the dynamic response of the fan blade in real time; A control unit is connected to the inertial vibrator, the direct-drive vibrator, and the response detection unit, respectively, and is used to control the swing excitation of the inertial vibrator and the flapping excitation of the direct-drive vibrator according to the dynamic response of the response detection unit.

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