Blade torsional fatigue test system and test method

Abstract

The invention relates to the technical field of blade testing, and discloses a blade torsional fatigue testing system and method.The blade torsional fatigue testing system comprises a test bed foundation and at least one torsional vibration exciter, and the test bed foundation is suitable for fixing the root of a blade; the torsional vibration exciter comprises a vibration excitation unit and a blade clamp, the blade clamp is suitable for being clamped and fixed to a blade, the vibration excitation unit is fixed to the blade clamp, and the vibration excitation unit is configured to apply torsional loading to the blade. The blade root is rigidly fixed through the test bed foundation, and displacement interference in the non-torsion direction is prevented from being generated in the test process; a blade clamp of the torsion vibration exciter is clamped on a specified section of a blade, a vibration excitation unit is directly fixed on the surface of the blade clamp through a mechanical connecting piece, the vibration excitation unit generates periodically changing rotating torque during operation, the torque is transmitted to the blade through the blade clamp, and the blade is forced to generate reciprocating torsion deformation around the axis of the blade. And the torsional fatigue load under the actual working condition is simulated.

Description

Technical Field

[0001] The present invention relates to the technical field of blade testing, and in particular to a blade torsional fatigue testing system and a testing method. Background Art

[0002] As the global wind power industry rapidly develops towards high power and long blades, the size and structural complexity of blades have increased significantly.

[0003] The longer the blade, the more nonlinear the torsional load and resulting torsional deformation it bears, typically proportional to the fourth power of the blade length. Consequently, a torsional response that was previously acceptable on smaller blades can become uncontrollable on larger blades, potentially leading to failures shortly after commissioning. Simultaneously, the natural vibration characteristics of large blades also change with size, with torsional natural frequencies decreasing and becoming closer to certain lower-order bending modes. This increases the likelihood of torsional-bending mode coupling and the associated risk of catastrophic blade failure.

[0004] As blade sizes increase, torsional loads and shear center offset have become significant components of the overall blade load. Existing techniques typically employ forced displacement to apply torsional loading to blades, often for static load testing. However, testing equipment and methods related to torsional fatigue, particularly devices for torsional mode excitation, are relatively rare. Summary of the Invention

[0005] In view of this, the present invention provides a blade torsional fatigue testing system and testing method to solve the problem of lack of testing equipment and methods related to torsional fatigue.

[0006] In a first aspect, the present invention provides a blade torsional fatigue testing system, comprising:

[0007] A test bench foundation, wherein the test bench foundation is suitable for fixing the blade root;

[0008] At least one torsional vibration exciter comprises an excitation unit and a blade fixture, wherein the blade fixture is suitable for being clamped and fixed on a blade, the excitation unit is fixed on the blade fixture, and the excitation unit is configured to apply a torsional load to the blade.

[0009] The root of the blade is rigidly fixed by the test bench foundation to prevent displacement interference in non-torsional directions during the test; the blade fixture of the torsional exciter is clamped on the specified cross-section of the blade, and the excitation unit is directly fixed to the surface of the blade fixture through a mechanical connector. When the excitation unit is in operation, a periodically changing rotational torque is generated, which is transmitted to the blade through the blade fixture, forcing the blade to undergo reciprocating torsional deformation around its axis, simulating the torsional fatigue load under actual working conditions.

[0010] Through the integrated design of the excitation unit and the blade fixture, the torsional load can be precisely applied, avoiding the additional bending deformation caused by traditional hydraulic loading; the synergistic effect of the test bench foundation and the exciter can ensure that the load direction is strictly distributed along the torsional axis of the blade, effectively separating the coupling effects of torsional and bending modes; at the same time, the structural form of the excitation unit directly fixed on the blade fixture simplifies the system complexity, reduces the equipment manufacturing cost, and supports customized loading requirements for different spanwise positions of the blade.

[0011] In an optional embodiment, the excitation unit includes:

[0012] A fixed base, fixed to the blade clamp;

[0013] a driving motor, fixed on the fixed base;

[0014] A gearbox is fixed on the fixed base, and the output end of the drive motor is connected to the gearbox;

[0015] a support frame connected to the torque output shaft of the gearbox, and configured to be driven by the torque output shaft of the gearbox to swing back and forth along the circumference of the torque output shaft;

[0016] an energy storage assembly configured to store angular momentum through rotational motion; the energy storage assembly being connected to the support frame, and the energy storage assembly and the support frame moving synchronously;

[0017] Wherein, the axial direction of the torque output shaft is perpendicular to the span-wise cross section of the blade.

[0018] In the present invention, the perpendicular relationship between the torque output shaft and the span-wise cross section of the blade ensures that the direction of the exciting force is always distributed along the torsional axis of the blade, thereby achieving pure torsional loading.

[0019] In an optional embodiment, the energy storage component includes:

[0020] A flywheel motor is fixed to the support frame, and the axial direction of the flywheel motor output shaft is parallel to the spanwise cross section of the blade;

[0021] A flywheel is fixed on the output shaft of the flywheel motor.

[0022] In the present invention, the rotation direction of the flywheel and the swing direction of the support frame cooperate with each other to ensure that the reverse torque is strictly distributed along the span direction of the blade, thereby realizing pure torsional loading without lateral force components; the angular momentum stored by the high-speed rotation of the flywheel can offset the instantaneous power fluctuations of the drive motor and maintain the amplitude of the exciting torque stable; at the same time, the flywheel and the flywheel motor are directly fixed coaxially, eliminating the coupling or gear structure in the traditional transmission chain, reducing mechanical energy loss, and the flywheel size and speed can be adjusted independently to adapt to the testing requirements of blades of different specifications.

[0023] In an optional embodiment, the excitation unit further includes a control cabinet, and the control cabinet is electrically connected to the flywheel motor and the drive motor.

[0024] In an optional embodiment, the number of the excitation units is two, and the two excitation units are centrally symmetrically arranged on the blade fixture.

[0025] The two excitation units work as follows: they are fixed on both sides of the blade fixture in a centrally symmetrical layout, and during operation, they synchronously generate rotational excitation torques of equal magnitude and opposite directions. The resultant vector of the two torques is strictly distributed along the span axis of the blade, forming a periodically changing pure torsional load; due to the centrally symmetrical setting, the lateral components of the excitation units cancel each other out in the plane of the blade fixture, leaving only the resultant torque along the span direction, forcing the blade to twist evenly around the axis; the synchronous reverse drive of the excitation units ensures consistent excitation frequency, avoiding vibration energy dissipation due to phase difference.

[0026] Furthermore, the centrally symmetrical layout eliminates the load component in the non-torsional direction, ensuring that the exciting force is accurately transmitted along the blade axis, thereby improving the accuracy of the test results; the superposition of the reverse torques of the two exciters exponentially increases the effective torsional load amplitude, meeting the testing requirements of large blades; the symmetrical distribution of the exciting force prevents the blade fixture from being subjected to local stress concentration, thereby extending the service life of the fixture; at the same time, the centrally symmetrical layout supports flexible adjustment of the exciter spacing to adapt to the installation requirements of blades of different sizes, thereby enhancing the versatility and scalability of the system.

[0027] In an optional embodiment, the two excitation units are arranged diagonally.

[0028] In an optional embodiment, the blade clamp includes an upper clamping plate, a lower clamping plate and a locking member, and the upper clamping plate and the lower clamping plate are provided with a notch on one side close to each other, and the two notches constitute a clamping cavity suitable for clamping the blade; the locking member connects the upper clamping plate and the lower clamping plate and locks them.

[0029] In an optional embodiment, the number of the blade clamps is two, the two blade clamps are arranged in parallel, and the torsional exciter is connected to both of the blade clamps.

[0030] In a second aspect, the present invention further provides a blade torsional fatigue testing method based on a blade torsional fatigue testing system, comprising the following steps:

[0031] Applying a cyclic torsional load to the test blade through a blade torsional fatigue test system;

[0032] Adjust the loading parameters to match the system resonance frequency with the blade's natural frequency;

[0033] Continue loading under resonance until a preset fatigue damage threshold is reached;

[0034] Collect blade dynamic response data and analyze fatigue characteristics.

[0035] By applying periodic torsional loads, the test blade is forced to twist and deform back and forth around the span-wise axis, simulating the alternating stress state in actual operation. The loading parameters are adjusted to make the system resonance frequency precisely match the blade's natural frequency, and the resonance effect is used to amplify the load amplitude, significantly accelerating the accumulation of fatigue damage. Under the resonance state, the load is continuously applied to the preset fatigue damage threshold. Through real-time acquisition of dynamic response data, the strain distribution, crack initiation and propagation behavior of the blade under different torsional load amplitudes and frequencies are recorded. The fatigue life curve is constructed based on the collected data, and the torsional stiffness degradation law and failure mode of the blade are analyzed.

[0036] Among them, the resonant frequency matching mechanism maximizes the energy input efficiency, compressing the traditional method's test cycle of several months to several weeks; the synergistic effect of periodic torsional load and natural frequency accurately reproduces the dynamic response of the blade under actual working conditions, improving the accuracy of fatigue characteristics analysis; quantitative control of preset fatigue damage thresholds avoids test deviations caused by overload or underload, ensuring the reliability of results; multi-dimensional acquisition of dynamic response data provides high-precision input for blade structure optimization design, shortens the R&D iteration cycle, and reduces the overall cost of full-scale testing.

[0037] In an optional embodiment, the step of applying a periodic torsional load to the test blade by the blade torsional fatigue testing system includes:

[0038] Fix the root of the test blade to the flange of the test bench foundation;

[0039] securing the torsional exciter to the blade;

[0040] Start the flywheel motor to make the flywheel rotate at a preset speed;

[0041] Start the drive motor and drive the support frame to swing back and forth through the gearbox to stimulate the torsional resonance of the test blade.

[0042] The root of the test blade is rigidly fixed to the flange of the test bench foundation, and the displacement interference in the non-torsional direction is eliminated by the anchoring effect between the flange and the foundation; the torsional exciter is fixed to the specified spanwise position of the blade, and the support frame of the exciter swings back and forth around the output shaft axis under the drive of the drive motor and gearbox. At the same time, the flywheel rotates at a preset high speed. The swing direction of the support frame cooperates with the rotation plane of the flywheel to generate a periodic torsional excitation torque through the change in the direction of angular momentum, forcing the blade to twist and deform back and forth around the spanwise axis; when the swing frequency of the support frame is adjusted to the torsional natural frequency of the blade, the system enters a resonant state, and the amplitude of the excitation torque is amplified by the resonance effect, accelerating the accumulation process of blade fatigue damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 This is a schematic structural diagram of a blade torsional fatigue testing system according to an embodiment of the present invention;

[0045] Figure 2 An exploded diagram of the structure of a torsional vibrator in a blade torsional fatigue testing system according to an embodiment of the present invention;

[0046] Figure 3 An exploded view of the parts of an excitation unit in a blade torsional fatigue testing system according to an embodiment of the present invention;

[0047] Figure 4 A schematic diagram of the motion mode of an excitation unit in a blade torsional fatigue testing system according to an embodiment of the present invention;

[0048] Figure 5 A side view of a torsional vibration exciter in a blade torsional fatigue testing system according to an embodiment of the present invention;

[0049] Figure 6 This is a partial side view of an excitation unit in a blade torsional fatigue testing system according to an embodiment of the present invention.

[0050] Description of reference numerals:

[0051] 1. First excitation unit; 11. Fixed foundation; 12. Drive motor; 13. Gearbox; 14. Control cabinet; 15. Support frame; 16. Flywheel motor; 17. Flywheel;

[0052] 2. The second excitation unit;

[0053] 3. First blade fixture;

[0054] 4. Second blade fixture;

[0055] 5. Torsional exciter;

[0056] 6. Leaves;

[0057] 7. Flange;

[0058] 8. Test bench foundation. DETAILED DESCRIPTION

[0059] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0060] As the global wind power industry rapidly develops towards high power and long blades, the size and structural complexity of blades have increased significantly.

[0061] The longer the blade, the more nonlinear the torsional load and resulting torsional deformation it bears, typically proportional to the fourth power of the blade length. Consequently, a torsional response that was previously acceptable on smaller blades can become uncontrollable on larger blades, potentially leading to failures shortly after commissioning. Simultaneously, the natural vibration characteristics of large blades also change with size, with torsional natural frequencies decreasing and becoming closer to certain lower-order bending modes. This increases the likelihood of torsional-bending mode coupling and the associated risk of catastrophic blade failure.

[0062] As blade sizes increase, torsional loads and shear center offset have become significant components of the overall blade load. Existing techniques typically employ forced displacement to apply torsional loading to blades, often for static load testing. However, testing equipment and methods related to torsional fatigue, particularly devices for torsional mode excitation, are relatively rare.

[0063] The following combination Figures 1 to 6 , describing embodiments of the present invention.

[0064] According to an embodiment of the present invention, on the one hand, a blade torsional fatigue testing system is provided, including a test bench base 8 and at least one torsional vibrator 5, wherein the test bench base 8 is suitable for fixing the root of the blade 6; the torsional vibrator 5 includes an excitation unit and a blade fixture, wherein the blade fixture is suitable for clamping and fixing on the blade 6, the excitation unit is fixed on the blade fixture, and the excitation unit is configured to apply a torsional load to the blade 6.

[0065] In the above embodiment, the root of the blade 6 is rigidly fixed by the test bench foundation 8 to prevent displacement interference in the non-torsional direction during the test; the blade fixture of the torsional exciter 5 is clamped on the specified cross-section of the blade 6, and the excitation unit is directly fixed to the surface of the blade fixture through a mechanical connector. When the excitation unit is in operation, a periodically changing rotational torque is generated, which is transmitted to the blade 6 through the blade fixture, forcing the blade 6 to undergo reciprocating torsional deformation around its axis, simulating the torsional fatigue load under actual working conditions.

[0066] In the above-mentioned embodiment, the integrated design of the excitation unit and the blade fixture can achieve the precise application of the torsional load, avoiding the additional bending deformation caused by traditional hydraulic loading; the synergistic effect of the test bench base 8 and the exciter can ensure that the load direction is strictly distributed along the torsional axis of the blade 6, effectively separating the coupling effects of the torsional and bending modes; at the same time, the structural form in which the excitation unit is directly fixed on the blade fixture simplifies the system complexity, reduces the equipment manufacturing cost, and supports customized loading requirements for different spanwise positions of the blade 6.

[0067] In one embodiment, the excitation unit includes a fixed base 11, a drive motor 12, a gearbox 13, a support frame 15 and an energy storage component. The fixed base 11 is fixed to the blade clamp, and the drive motor 12 is fixed on the fixed base 11; the gearbox 13 is fixed on the fixed base 11, and the output end of the drive motor 12 is connected to the gearbox 13; the support frame 15 is connected to the torque output shaft of the gearbox 13, and the support frame 15 is configured to be driven by the torque output shaft of the gearbox 13 to swing back and forth along the circumference of the torque output shaft; the energy storage component is configured to store angular momentum through rotational motion; the energy storage component is connected to the support frame 15, and the energy storage component and the support frame 15 move synchronously; wherein, the axial direction of the torque output shaft is perpendicular to the span-wise cross-section of the blade 6.

[0068] In the above embodiment, the working mode of the excitation unit is as follows: after the driving motor 12 is started, the power is transmitted to the torque output shaft through the gearbox 13, driving the support frame 15 to swing back and forth around the axis of the torque output shaft; the energy storage component moves synchronously with the support frame 15; since the axial direction of the torque output shaft is perpendicular to the span-wise section of the blade 6, the swing direction of the support frame 15 is strictly limited to the vertical plane of the span-wise section of the blade 6, so that the angular momentum change of the energy storage component is directly converted into a torque perpendicular to the span-wise direction of the blade 6, and the torque is transmitted to the blade 6 through the rigid connection between the fixed base 11 and the blade clamp, forcing the blade 6 to produce periodic torsional deformation. Among them, Figure 2 In the embodiment, the spanwise cross section of the blade 6 is parallel to the plane a of the blade fixture.

[0069] In the above embodiment, the perpendicular relationship between the torque output shaft and the span-wise cross section of the blade 6 ensures that the direction of the exciting force is always distributed along the torsional axis of the blade 6 , thus achieving pure torsional loading.

[0070] In one embodiment, the energy storage assembly includes a flywheel motor 16 and a flywheel 17. The flywheel motor 16 is fixed to the support frame 15, and the axial direction of the output shaft of the flywheel motor 16 is parallel to the span-wise section of the blade 6; the flywheel 17 is fixed on the output shaft of the flywheel motor 16.

[0071] In the above embodiment, the energy storage component works as follows: after the flywheel motor 16 is started, it drives the flywheel 17 to rotate at high speed around the output shaft, and stores angular momentum through rotational motion; since the output shaft axis of the flywheel motor 16 is parallel to the span-wise cross-section of the blade 6, when the support frame 15 is driven to swing, the flywheel 17 generates a reverse torque due to the change in the direction of the angular momentum. This torque is transmitted to the blade clamp through the fixed connection between the support frame 15 and the flywheel motor 16, forcing the blade 6 to undergo periodic torsional deformation around the span-wise axis.

[0072] In the above-mentioned embodiment, the rotation direction of the flywheel 17 cooperates with the swing direction of the support frame 15 to ensure that the reverse torque is strictly distributed along the span direction of the blade 6, thereby realizing pure torsional loading without lateral force components; the angular momentum stored by the high-speed rotation of the flywheel 17 can offset the instantaneous power fluctuations of the drive motor 12, and maintain the amplitude of the exciting torque stable; at the same time, the flywheel 17 and the flywheel motor 16 are directly coaxially fixed, eliminating the coupling or gear structure in the traditional transmission chain, reducing mechanical energy loss, and the size and speed of the flywheel 17 can be adjusted independently to adapt to the testing requirements of blades 6 of different specifications.

[0073] In one embodiment, the excitation unit further includes a control cabinet, which is electrically connected to the flywheel motor 16 and the drive motor 12. The control cabinet can use existing components and can control the flywheel motor 16 and the drive motor 12.

[0074] In one embodiment, the number of the excitation units is two, and the two excitation units are centrally symmetrically arranged on the blade fixture.

[0075] like Figure 2 As shown, in this embodiment, a first excitation unit 1 and a second excitation unit 2 are provided. The two excitation units are installed on both sides of the blade fixture in a centrally symmetrical layout. During operation, they synchronously generate rotational excitation torques of equal magnitude and opposite directions. The synthetic vector of the two torques is strictly distributed along the span axis of the blade 6, forming a periodically changing pure torsional load. Due to the centrally symmetrical arrangement, the lateral components of the two excitation units cancel each other out, preventing the blade fixture from bearing additional bending stress. At the same time, the superposition effect of the excitation torques makes the torque distribution of the span section of the blade 6 uniform.

[0076] Furthermore, the symmetrical layout of the dual excitation units eliminates interference from the component forces in the non-torsional direction, ensuring that the load is strictly transmitted along the axis of the blade 6, thereby improving test accuracy; the superposition of the reverse torques of the two excitation units can exponentially increase the effective torsional load amplitude, adapting to the testing requirements of large-size blades 6; the centrally symmetrical structure enables self-balancing of the vibration energy between the excitation units, reducing the impact load on the test bench foundation 8 and extending the life of the equipment; in addition, the symmetrical layout supports flexible adjustment of the spacing between the excitation units, adapting to the installation requirements of blades 6 of different specifications and enhancing the versatility of the system.

[0077] In one embodiment, the two excitation units are arranged diagonally.

[0078] In one embodiment, the blade clamp includes an upper clamping plate, a lower clamping plate and a locking member. The upper clamping plate and the lower clamping plate are provided with a notch on one side close to each other, and the two notches constitute a clamping cavity suitable for clamping the blade 6; the locking member connects the upper clamping plate and the lower clamping plate and locks them.

[0079] The locking member can be a stud and nuts configured as both ends of the bolt. The two ends of the stud are inserted into the upper clamping plate and the lower clamping plate, and the upper clamping plate and the lower clamping plate are fastened by tightening the nuts.

[0080] The working method of the blade clamp is: the upper clamping plate and the lower clamping plate are placed on the upper and lower sides of the blade 6 respectively, and the upper and lower clamping plates are driven close to each other by the locking parts, so that the notches of the upper and lower clamping plates are closed to form a clamping cavity that fits tightly with the cross section of the blade 6, and the blade 6 is rigidly fixed in the clamping cavity; the shape of the notch matches the cross section of the blade 6 to ensure that there is no local stress concentration on the blade 6 under torsional load.

[0081] In one embodiment, there are two blade fixtures, which are arranged in parallel, and the torsional vibration exciter 5 is connected to both blade fixtures.

[0082] like Figure 2 As shown, in this embodiment, a first blade fixture 3 and a second blade fixture 4 are provided. The two blade fixtures are arranged in parallel on both sides of the span axis of the blade 6. The torsional vibrator 5 is rigidly connected to the two fixtures. During operation, the rotational torque generated by the vibrator is simultaneously transmitted to the clamping ends of the two fixtures, forcing the blade 6 to twist synchronously around the span axis between the parallel fixtures. Since the distance between the two fixtures is fixed and they are linked with the vibrator, the load direction they apply is strictly symmetrically distributed, forming a uniform torsional load along the span direction of the blade 6. The effects are as follows: the parallel layout of the two fixtures enables the excitation torque to be uniformly transmitted along the length direction of the blade 6, eliminating the local stress concentration caused by single-point loading; the synchronous connection between the vibrator and the two fixtures ensures that the torque direction is consistent, avoiding bending mode coupling caused by asymmetric loading; the rigid constraint of the parallel fixture spacing suppresses the vibration component of the blade 6 in the non-torsional direction, thereby improving the test accuracy.

[0083] According to an embodiment of the present invention, on the other hand, a blade torsional fatigue testing method based on a blade torsional fatigue testing system is provided, comprising the following steps:

[0084] Applying a periodic torsional load to the test blade 6 by a blade torsional fatigue test system;

[0085] Adjust the loading parameters to match the system resonance frequency with the natural frequency of blade 6;

[0086] Continue loading under resonance until a preset fatigue damage threshold is reached;

[0087] The dynamic response data of blade 6 is collected and the fatigue characteristics are analyzed.

[0088] Specifically, by applying periodic torsional loads, the test blade 6 is forced to torsionally deform around the spanwise axis, simulating the alternating stress state in actual operation; the loading parameters are adjusted to make the system resonance frequency accurately match the natural frequency of the blade 6, and the load amplitude is amplified by the resonance effect, significantly accelerating the accumulation process of fatigue damage; the load is continuously applied to the preset fatigue damage threshold in the resonant state, and the strain distribution, crack initiation and propagation behavior of the blade 6 under different torsional load amplitudes and frequencies are recorded through real-time acquisition of dynamic response data; a fatigue life curve is constructed based on the collected data, and the torsional stiffness degradation law and failure mode of the blade 6 are analyzed.

[0089] Among them, the resonant frequency matching mechanism maximizes the energy input efficiency, compressing the test cycle of several months of traditional methods to several weeks; the synergistic effect of periodic torsional load and natural frequency accurately reproduces the dynamic response of blade 6 under actual working conditions, improving the accuracy of fatigue characteristics analysis; quantitative control of preset fatigue damage thresholds avoids test deviations caused by overload or underload, ensuring the reliability of results; multi-dimensional acquisition of dynamic response data provides high-precision input for the structural optimization design of blade 6, shortens the R&D iteration cycle, and reduces the overall cost of full-scale testing.

[0090] In one embodiment, the step of applying a periodic torsional load to the test blade 6 by the blade torsional fatigue testing system includes:

[0091] Fix the root of the test blade 6 to the flange 7 of the test bench foundation 8;

[0092] Fixing the torsional vibration exciter 5 to the blade 6;

[0093] Starting the flywheel motor 16 to rotate the flywheel 17 at a preset speed;

[0094] The driving motor 12 is started to drive the support frame 15 to swing back and forth through the gearbox 13 to stimulate the torsional resonance of the test blade 6.

[0095] Specifically, the root of the test blade 6 is rigidly fixed on the flange 7 of the test bench foundation 8, and the displacement interference in the non-torsional direction is eliminated by the anchoring effect between the flange 7 and the foundation; the torsional exciter 5 is fixed to the specified spanwise position of the blade 6, and the support frame 15 of the exciter swings back and forth around the output shaft axis under the drive of the drive motor 12 and the gearbox 13, while the flywheel 17 rotates at a preset high speed. The swing direction of the support frame 15 cooperates with the rotation plane of the flywheel 17 to generate a periodic torsional excitation torque through the change in the direction of angular momentum, forcing the blade 6 to torsionally deform back and forth around the spanwise axis; when the swing frequency of the support frame 15 is adjusted to the torsional natural frequency of the blade 6, the system enters a resonant state, and the amplitude of the excitation torque is amplified by the resonance effect, accelerating the accumulation process of fatigue damage of the blade 6.

[0096] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A blade torsional fatigue testing system, characterized in that: include: A test bench foundation (8), wherein the test bench foundation (8) is suitable for fixing the root of the blade (6); At least one torsional vibration exciter (5) comprises an excitation unit and a blade fixture, wherein the blade fixture is suitable for being clamped and fixed on a blade (6), the excitation unit is fixed on the blade fixture, and the excitation unit is configured to apply a torsional load to the blade (6).

2. The blade torsional fatigue testing system according to claim 1, characterized in that: The excitation unit includes: A fixed base (11) fixed to the blade fixture; A driving motor (12) is fixed on the fixed base (11); A gearbox (13) is fixed on the fixed base (11), and an output end of the drive motor (12) is connected to the gearbox (13); A support frame (15) is connected to the torque output shaft of the gearbox (13), and the support frame (15) is configured to be driven by the torque output shaft of the gearbox (13) to swing back and forth along the circumference of the torque output shaft; An energy storage component is configured to store angular momentum through rotational motion; the energy storage component is connected to the support frame (15), and the energy storage component and the support frame (15) move synchronously; The axial direction of the torque output shaft is perpendicular to the spanwise cross section of the blade (6).

3. The blade torsional fatigue testing system according to claim 2, characterized in that: The energy storage component includes: A flywheel motor (16) is fixed to the support frame (15), and the axial direction of the output shaft of the flywheel motor (16) is parallel to the spanwise cross section of the blade (6); A flywheel (17) is fixed on the output shaft of the flywheel motor (16).

4. The blade torsional fatigue testing system according to claim 3, characterized in that: The excitation unit further includes a control cabinet (14), and the control cabinet (14) is electrically connected to the flywheel motor (16) and the drive motor (12).

5. The blade torsional fatigue testing system according to any one of claims 1 to 3, characterized in that: The number of the excitation units is two, and the two excitation units are centrally symmetrically arranged on the blade fixture.

6. The blade torsional fatigue testing system according to claim 5, characterized in that: The two excitation units are arranged diagonally.

7. The blade torsional fatigue testing system according to claim 5, characterized in that: The blade clamp comprises an upper clamping plate, a lower clamping plate and a locking piece, wherein the upper clamping plate and the lower clamping plate are provided with notches on one side close to each other, and the two notches form a clamping cavity suitable for clamping the blade (6); the locking piece connects the upper clamping plate and the lower clamping plate and locks them.

8. The blade torsional fatigue testing system according to claim 7, characterized in that: There are two blade clamps, the two blade clamps are arranged in parallel, and the torsional vibration exciter (5) is connected to both blade clamps.

9. A blade torsional fatigue testing method based on the blade torsional fatigue testing system according to any one of claims 1 to 8, characterized in that: The following steps are involved: Applying a periodic torsional load to a test blade (6) through a blade torsional fatigue test system; Adjusting the loading parameters to match the system resonance frequency with the natural frequency of the blade (6); Continue loading under resonance until a preset fatigue damage threshold is reached; The dynamic response data of the blade (6) is collected and the fatigue characteristics are analyzed.

10. The blade torsional fatigue testing method according to claim 9, characterized in that: The step of applying a periodic torsional load to the test blade (6) by the blade torsional fatigue test system comprises: Fixing the root of the test blade (6) to the flange (7) of the test bench foundation (8); Fixing the torsional vibration exciter (5) to the blade (6); Starting the flywheel motor (16) to rotate the flywheel (17) at a preset speed; The driving motor (12) is started to drive the support frame (15) to swing back and forth through the gearbox (13), thereby exciting the torsional resonance of the test blade (6).

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