Blade multi-degree-of-freedom traction loading device and fatigue test method

Abstract

The invention relates to the technical field of fatigue testing, and discloses a blade multi-degree-of-freedom traction loading device and a fatigue testing method.The blade multi-degree-of-freedom traction loading device comprises a rail supporting structure, a blade base structure, a blade clamp and a multi-direction loading assembly, and the blade base structure bears and fixes the root of a tested blade; the blade clamp is fixed with the blade; the multidirectional loading assembly comprises a track and at least one traction actuator, and the track is fixed on the track supporting structure; the traction actuator is arranged on the track, and the traction actuator is configured to be capable of moving along the track; the traction actuator comprises a track displacement driving mechanism and a traction mechanism; the traction actuator is configured to move on the track through the track displacement driving mechanism; the traction mechanism is connected with the blade clamp, and the traction mechanism is configured to apply an adjustable traction force to the to-be-tested blade. The traction direction is adjusted by pulling the actuator to move to different positions along the track, and different traction forces are applied in cooperation with the traction mechanism, so that multiple loading modes are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of fatigue testing, and in particular to a blade multi-degree-of-freedom traction loading device and a fatigue testing method. Background Art

[0002] With the large-scale development of wind turbines, the length of megawatt-class blades has exceeded hundreds of meters, and the verification of their structural reliability faces severe challenges.

[0003] Full-size blade testing primarily involves static and fatigue testing. Static blade testing involves applying static loads (such as bending and torsion) to the blades, typically to 150%-200% of the design value to test safety margins. Blade strain, displacement, and local deformation are monitored, as well as the presence of cracks or delamination, to determine the structural reliability of the blades. Blade fatigue testing involves cyclic loading to simulate the alternating stresses experienced in long-term blade operation. Under the influence of a resonant excitation system, the blades undergo millions of flapping and shimmying motions to verify their structural reliability. Fatigue testing typically lasts several months or even a year.

[0004] Among them, the fatigue testing content of blades mainly includes flapping fatigue testing, shimmy fatigue testing, and torsional fatigue testing. The flapping fatigue test is to make the blade complete millions of reciprocating deformation movements in the up and down (pressure side-suction side) bending direction; the shimmy fatigue test is to make the blade complete millions of reciprocating deformation movements in the front and back (leading edge-trailing edge) bending direction. The current standards do not require the implementation of torsional fatigue testing, and there are currently few related testing equipment and supporting methods in the industry. The fatigue testing types of blades mainly include uniaxial fatigue testing and biaxial fatigue testing. The uniaxial fatigue test often uses the resonant excitation method: an eccentric hammer exciter is installed at the appropriate position of the blade, and the excitation frequency is adjusted to be close to the natural frequency of the blade to induce large vibrations in the blade; the biaxial fatigue test test machine is equipped with two independent excitation units. The servo motor repeatedly pushes the connecting rod connected to the blade to achieve forced vibration loading of the blade in two directions. Uniaxial and biaxial fatigue tests each have their applicable boundaries. Uniaxial testing is simple and reliable, but it proves insufficient when blades are larger and subjected to complex loads. Biaxial testing is realistic and efficient, but requires overcoming equipment complexity and control challenges. In the current industry, uniaxial testing is still the dominant method for blades.

[0005] However, both uniaxial and multi-axial tests verify the fatigue reliability of the blade in the flapping and swing directions, while neither of these two types of testing equipment has the ability to verify the torsional fatigue reliability of the blade. Summary of the Invention

[0006] In view of this, the present invention provides a blade multi-degree-of-freedom traction loading device and fatigue testing method to solve the problem of simultaneously verifying the blade's flapping, shimmying and torsional fatigue reliability.

[0007] In a first aspect, the present invention provides a blade multi-degree-of-freedom traction loading device, comprising:

[0008] A ground fixing assembly, comprising a track support structure and a blade base structure, wherein the blade base structure supports and fixes the root of the blade to be measured;

[0009] a blade clamp, fixed to the blade;

[0010] Multi-directional loading components, including:

[0011] a track, fixed to the track support structure;

[0012] at least one traction actuator disposed on the track, and the traction actuator is configured to be displaceable along the track;

[0013] The traction actuator includes a track displacement drive mechanism and a traction mechanism; the traction actuator is configured to move on the track through the track displacement drive mechanism to change the traction direction of the blade by the traction actuator; the traction mechanism is connected to the blade clamp, and the traction mechanism is configured to apply an adjustable traction force to the blade to be tested.

[0014] The blade base structure in the ground fixing assembly fixes the root of the blade to be measured through a positioning flange, the blade clamp is connected to the blade, the track of the multi-directional loading assembly is fixed to the track support structure, and at least one traction actuator is set on the track, which can be displaced along the track by the track displacement driving mechanism to change the traction direction of the blade. At the same time, the traction mechanism is connected to the blade clamp, and an adjustable traction force can be applied to the blade to be measured by adjusting the traction mechanism; during the working process, each traction actuator can act individually or in coordination, for example, by moving different traction actuators to different positions along the track to adjust the traction direction, and then cooperating with the traction mechanism to apply traction forces of different sizes, thereby realizing multiple loading modes.

[0015] In an optional embodiment, the track displacement driving mechanism includes:

[0016] Drive motor;

[0017] A power gear is fixed to the output shaft of the drive motor, and the power gear is engaged with the meshing teeth on the track;

[0018] The power gear is configured to be driven by the driving motor to drive the traction actuator to move along the track.

[0019] This driving method based on gear meshing transmission can provide a stable and controllable driving force for the movement of the traction actuator, ensuring the smoothness and accuracy of the traction actuator's movement along the track, so that the traction actuator can stay or move at any position on the track according to test requirements, thereby accurately changing the traction direction of the blade, providing a reliable direction adjustment basis for realizing complex load loading with multiple degrees of freedom and multi-axis coupling on the blade, and effectively improving the flexibility and accuracy of the loading device in simulating the actual stress scenarios of the blade.

[0020] In an optional embodiment, the track displacement driving mechanism further includes:

[0021] a supporting frame, the driving motor is fixed to the supporting frame, and the power gear is rotatably disposed on the supporting frame;

[0022] The driven wheel group is movably connected to the support frame, and the driven wheel group is configured to provide support and limitation for the traction actuator.

[0023] The support frame and the driven wheel set form a stable mechanical support structure. The driven wheel set reduces the movement resistance of the traction actuator through the form of a rolling friction pair. At the same time, it cooperates with the meshing transmission of the power gear to ensure that the traction actuator moves on the track both smoothly and accurately, effectively improving the reliability of traction direction adjustment.

[0024] In an optional embodiment, the driven wheel set includes:

[0025] An inner roller is movably connected to the support frame, and the inner roller abuts against the inner wall of the track;

[0026] The outer roller is movably connected to the support frame, and the inner roller abuts against the inner and outer side walls of the track;

[0027] The inner roller and the outer roller are configured to support the traction actuator on the track.

[0028] The inner roller and the outer roller are both movably connected to the support frame. The wheel surface of the inner roller is in close contact with the inner wall of the track, and the wheel surface of the outer roller is in contact with the outer wall of the track, forming a double-sided clamping support for the traction actuator; when the traction actuator moves along the track, the inner roller and the outer roller roll synchronously along the inner and outer walls of the track. Through the coordinated action of the two, the traction actuator is confined to the preset path of the track, so that it can only translate along the circumferential direction of the track, and cannot move radially or tilt.

[0029] In an optional embodiment, the number of the inner rollers is at least two, or the number of the outer rollers is at least two, and the three rollers are distributed in a triangle.

[0030] The triangularly distributed roller structure utilizes the principle of geometric stability to significantly improve the support stiffness and anti-overturning ability of the traction actuator on the track. Even when the traction force direction changes or unbalanced load occurs during loading, the force balance effect of the triangular fulcrum can maintain the stable movement of the traction actuator. Compared with the traditional double-roller parallel distribution mode, the triangular distribution design can effectively reduce the shaking and deviation of the traction actuator.

[0031] In an optional embodiment, the traction mechanism includes:

[0032] a drum rotatably disposed on the support frame, a traction rope being wound around the surface of the drum, and a free end of the traction rope being adapted to be fixed to the blade;

[0033] a traction motor connected to the drum;

[0034] The drum is configured to be driven by the traction motor to apply traction force to the blade via the traction rope.

[0035] This traction mechanism, based on the drum winding principle, can achieve continuous adjustment and dynamic loading of traction force through precise control of the traction motor, meeting the requirements of different load amplitudes and frequencies in blade fatigue testing; the winding of the traction rope and the drum provides a stable force transmission path, and combined with the rigid support of the support frame, it can ensure that the application of traction force has high linearity and repeatability; at the same time, the low friction characteristics of the drum rotation and the servo control capability of the traction motor enable the mechanism to quickly respond to the instructions of the control system and achieve real-time adjustment of the traction force component in the multi-axis composite load of the blade, providing a flexible and reliable power execution unit for simulating the complex stress state of the blade in actual operation. Specifically, by changing the reciprocating frequency of the traction rope, the periodic loading of the fatigue load is achieved, and the traction frequency of each traction mechanism can be different.

[0036] In an optional embodiment, the track is ring-shaped, and the number of the traction actuators is at least three.

[0037] In an optional embodiment, the track support structure is height-adjustable.

[0038] In a second aspect, the present invention further provides a fatigue testing method based on a blade multi-degree-of-freedom traction loading device, comprising the following steps:

[0039] Connecting three traction actuators to three different sides of the blade fixture, and adjusting the positions of the three traction actuators on the track through the track displacement drive mechanism to form a predetermined spatial angle;

[0040] The traction mechanism of each traction actuator is controlled to apply periodic loading to the blade.

[0041] In this fatigue testing method, the working principle is as follows: first, three traction actuators are connected to three different sides of the blade fixture (for example, spaced 120 degrees apart circumferentially). The track displacement drive mechanism of each traction actuator independently adjusts its circumferential position on the track, so that the traction directions of the three traction actuators form a predetermined spatial angle to match the multi-directional load angles in the actual blade operating conditions. Then, the traction mechanism of each traction actuator is synchronously or asynchronously controlled by the control system to apply periodic traction forces to the blade at a set frequency and load amplitude. For example, this can simulate an up-and-down reciprocating load in the blade's flapping direction, a back-and-forth reciprocating load in the shimmy direction, or a combined load of the two. The effect is: through the spatial position control of the three traction actuators and the coordinated loading of the traction force, the multi-axial composite stress state that the blade is subjected to in actual operation can be accurately simulated. Compared with the traditional uniaxial test mode that requires loading in different directions in stages, this method can realize the simultaneous application of multi-directional loads at one time, significantly shortening the test cycle; the setting of the predetermined spatial angle makes the load direction closer to the multi-directional force scenario under actual wind conditions, thereby improving the reliability of the fatigue test results. It is especially suitable for verifying the structural durability of the blade under complex load coupling, and providing more comprehensive experimental data support for blade design optimization.

[0042] In an optional embodiment, controlling the traction mechanism of each traction actuator to apply periodic loading to the blade includes:

[0043] The traction motors of the traction actuators are controlled to output periodically varying traction rope lengths, causing the test blade to produce three-axis coupled deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] 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.

[0045] Figure 1 This is a schematic structural diagram of a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention;

[0046] Figure 2 This is a schematic structural diagram of a multi-directional loading assembly in a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention;

[0047] Figure 3 An exploded view of a traction actuator in a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention;

[0048] Figure 4A partial view of a traction actuator in a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention;

[0049] Figure 5 Schematic diagram of four traction actuators applying flapping loads (single axis) to a blade in a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention;

[0050] Figure 6 Schematic diagram of a blade multi-degree-of-freedom traction loading device in accordance with an embodiment of the present invention, wherein four traction actuators apply a shimmy load (single axis) to the blade;

[0051] Figure 7 Schematic diagram of four traction actuators applying flapping-shimmy-torsion coupled loads (three axes) to a blade in a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention;

[0052] Figure 8 Schematic diagram of two traction actuators applying torsional load (single axis) to a blade in a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention;

[0053] Figure 9 In a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention, three traction actuators apply flapping-shimmy-torsion coupled loads (three axes) to the blade.

[0054] Figure 10 In a blade multi-degree-of-freedom traction loading device according to an embodiment of the present invention, a traction actuator applies a flapping load (single axis) to the blade.

[0055] Description of reference numerals:

[0056] 1. Track support structure;

[0057] 2. Blade base structure;

[0058] 3. Leaves;

[0059] 4. Blade fixture;

[0060] 5. Track;

[0061] 6. Traction actuator; 61. Drive motor; 62. Power gear; 63. Support frame; 64. Inner roller; 65. Outer roller; 66. Drum; 67. Traction rope; 68. Traction motor; 69. Connector;

[0062] 7. Positioning flange. DETAILED DESCRIPTION

[0063] 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.

[0064] With the large-scale development of wind turbines, the length of megawatt-class blades has exceeded hundreds of meters, and the verification of their structural reliability faces severe challenges.

[0065] Full-size blade testing primarily involves static and fatigue testing. Static blade testing involves applying static loads (such as bending and torsion) to the blades, typically to 150%-200% of the design value to test safety margins. Blade strain, displacement, and local deformation are monitored, as well as the presence of cracks or delamination, to determine the structural reliability of the blades. Blade fatigue testing involves cyclic loading to simulate the alternating stresses experienced in long-term blade operation. Under the influence of a resonant excitation system, the blades undergo millions of flapping and shimmying motions to verify their structural reliability. Fatigue testing typically lasts several months or even a year.

[0066] Among them, the fatigue testing content of blades mainly includes flapping fatigue testing, shimmy fatigue testing, and torsional fatigue testing. The flapping fatigue test is to make the blade complete millions of reciprocating deformation movements in the up and down (pressure side-suction side) bending direction; the shimmy fatigue test is to make the blade complete millions of reciprocating deformation movements in the front and back (leading edge-trailing edge) bending direction. The current standards do not require the implementation of torsional fatigue testing, and there are currently few related testing equipment and supporting methods in the industry. The fatigue testing types of blades mainly include uniaxial fatigue testing and biaxial fatigue testing. The uniaxial fatigue test often uses the resonant excitation method: an eccentric hammer exciter is installed at the appropriate position of the blade, and the excitation frequency is adjusted to be close to the natural frequency of the blade to induce large vibrations in the blade; the biaxial fatigue test test machine is equipped with two independent excitation units. The servo motor repeatedly pushes the connecting rod connected to the blade to achieve forced vibration loading of the blade in two directions. Uniaxial and biaxial fatigue tests each have their applicable boundaries. Uniaxial testing is simple and reliable, but it proves insufficient when blades are larger and subjected to complex loads. Biaxial testing is realistic and efficient, but requires overcoming equipment complexity and control challenges. In the current industry, uniaxial testing is still the dominant method for blades.

[0067] However, both uniaxial and multi-axial tests verify the fatigue reliability of the blade in the flapping and swing directions, while neither of these two types of testing equipment has the ability to verify the torsional fatigue reliability of the blade.

[0068] In view of this, the present embodiment provides a blade multi-degree-of-freedom traction loading device and fatigue testing method to solve the problem of simultaneously verifying the blade's flapping, shimmying and torsional fatigue reliability.

[0069] The following combination Figures 1 to 10 , describing embodiments of the present invention.

[0070] According to an embodiment of the present invention, on the one hand, a blade multi-degree-of-freedom traction loading device is provided, including a ground fixing component, a blade clamp 4 and a multi-directional loading component, the ground fixing component includes a track support structure 1 and a blade base structure 2, the blade base structure 2 supports the root of the measured blade 3 for fixation; the blade clamp 4 is fixed to the blade 3; the multi-directional loading component includes a track 5 and at least one traction actuator 6, the track 5 is fixed on the track support structure 1; the traction actuator 6 is arranged on the track 5, and the traction actuator 6 is configured to be displaceable along the track 5; the traction actuator 6 includes a track displacement drive mechanism and a traction mechanism; the traction actuator 6 is configured to move on the track 5 via the track displacement drive mechanism to change the traction direction of the traction actuator 6 on the blade 3; the traction mechanism is connected to the blade clamp 4, and the traction mechanism is configured to apply an adjustable traction force to the blade 3 to be measured.

[0071] In the above-described embodiment, the blade base structure 2 in the ground-mounted assembly secures the root of the blade 3 under test via a positioning flange 7. The blade fixture 4 is connected to the blade 3. The track 5 of the multi-directional loading assembly is fixed to the track support structure 1. The traction actuator 6 is disposed on the track 5 and can be displaced along the track 5 by a track displacement drive mechanism to change the traction direction of the blade 3. Simultaneously, the traction mechanism is connected to the blade fixture 4, and adjustable traction force can be applied to the blade 3 under test by adjusting the traction mechanism. During operation, the traction direction is adjusted by moving the traction actuator 6 to different positions along the track 5, and different traction forces are applied in conjunction with the traction mechanism, thereby achieving a variety of different loading modes.

[0072] In the above embodiment, when there are multiple traction actuators 6, the track displacement and traction force adjustment of the traction actuator 6 can flexibly realize the multi-directional and multi-combination load application to the blade 3. Compared with the traditional single-axis or dual-axis test device, it can more accurately simulate the complex load conditions that the blade 3 may withstand during actual operation, especially the three-axis load loading of flapping-oscillation-torsion coupling, thereby improving the accuracy and comprehensiveness of the fatigue test of the blade 3. At the same time, through the coordinated control of multiple traction actuators 6, the test steps can be reduced, the test cycle can be shortened, and the test efficiency can be improved.

[0073] In one embodiment, the track displacement drive mechanism includes a drive motor 61 and a power gear 62. The power gear 62 is fixed to the output shaft of the drive motor 61 and engages with the meshing teeth on the track 5. The power gear 62 is configured to be driven by the drive motor 61 to drive the traction actuator 6 to move along the track 5.

[0074] In this embodiment, the working mode of the track displacement drive mechanism is as follows: the drive motor 61 generates rotational power after being energized, and its output shaft drives the power gear 62 fixedly connected to it to rotate synchronously. Since the power gear 62 is in a meshing state with the meshing teeth on the track 5, the rotation of the power gear 62 will push the traction actuator 6 to move along the circumferential direction of the track 5 through the meshing force between the teeth; in this process, the drive motor 61 can accurately adjust the speed and rotation direction through the control system, and then control the rotation speed and stroke of the power gear 62, so as to realize the precise positioning and displacement of the traction actuator 6 on the track 5.

[0075] The effect is that this driving method based on gear meshing transmission can provide a stable and controllable driving force for the movement of the traction actuator 6, ensure the smoothness and accuracy of the movement of the traction actuator 6 along the track 5, and enable the traction actuator 6 to stay or move at any position on the track 5 according to the test requirements, thereby accurately changing the traction direction of the blade 3, providing a reliable direction adjustment basis for realizing complex load loading of multiple degrees of freedom and multi-axis coupling on the blade 3, and effectively improving the flexibility and accuracy of the loading device in simulating the actual stress scenario of the blade 3.

[0076] In one embodiment, the track displacement drive mechanism also includes a support frame 63 and a driven wheel group, the drive motor 61 is fixed to the support frame 63, and the power gear 62 is rotatably set on the support frame 63; the driven wheel group is movably connected to the support frame 63, and the driven wheel group is configured to provide support and limitation for the traction actuator 6.

[0077] In this embodiment, the driving motor 61 is fixed to the support frame 63, and its output shaft drives the power gear 62 to rotate on the support frame 63. The power gear 62 drives the entire traction actuator 6 to move along the track 5 by meshing with the meshing teeth of the track 5; at the same time, the driven wheel group is movably connected to the support frame 63, and its wheel surface is in close contact with the inner surface of the track 5. During the movement of the traction actuator 6, the driven wheel group rolls along the contour of the track 5. On the one hand, it provides support force for the traction actuator 6 and balances the lateral force generated when the power gear 62 engages. On the other hand, by limiting the relative position of the traction actuator 6 and the track 5, it constrains it to move only along the circumferential direction of the track 5, avoiding radial displacement or shaking.

[0078] Furthermore, the support frame 63 and the driven wheel group form a stable mechanical support structure. The driven wheel group reduces the movement resistance of the traction actuator 6 through the form of a rolling friction pair, and at the same time cooperates with the meshing transmission of the power gear 62 to ensure that the traction actuator 6 moves on the track 5 both smoothly and accurately, effectively improving the reliability of the traction direction adjustment.

[0079] In one embodiment, the driven wheel group includes an inner roller 64 and an outer roller 65, the inner roller 64 is movably connected to the support frame 63, and the inner roller 64 abuts against the inner wall of the track 5; the outer roller 65 is movably connected to the support frame 63, and the inner roller 64 abuts against the inner and outer walls of the track 5; the inner roller 64 and the outer roller 65 are configured to support the traction actuator 6 on the track 5.

[0080] In this embodiment, the inner roller 64 and the outer roller 65 are both movably connected to the support frame 63, the wheel surface of the inner roller 64 is in close contact with the inner wall of the track 5, and the wheel surface of the outer roller 65 is in contact with the outer wall of the track 5, forming a double-sided clamping support for the traction actuator 6; when the traction actuator 6 moves along the track 5, the inner roller 64 and the outer roller 65 roll synchronously along the inner and outer walls of the track 5, and through the coordinated action of the two, the traction actuator 6 is confined to the preset path of the track 5, so that it can only translate circumferentially along the track 5, and cannot move radially or tilt.

[0081] This double-sided support structure composed of the inner roller 64 and the outer roller 65 provides a two-way limit for the traction actuator 6 like a "track clamp", which significantly improves the stability of the traction actuator 6 during movement, and effectively resists the lateral force generated when the power gear 62 is engaged and the reaction force during traction loading; at the same time, the rolling friction form reduces the movement resistance, making the movement of the traction actuator 6 smoother and more flexible, ensuring the accuracy of the traction direction adjustment, and providing reliable mechanical support for trajectory control during multi-axis load loading, further enhancing the operation reliability and structural durability of the entire loading device under complex working conditions.

[0082] In one embodiment, the number of the inner rollers 64 is at least two, or the number of the outer rollers 65 is at least two, and the three rollers are distributed in a triangle.

[0083] In this embodiment, when the number of inner rollers 64 is at least two or the number of outer rollers 65 is at least two, three rollers (including two rollers of the same type and one roller on the opposite side) are distributed in a triangular shape in the contact area between the support frame 63 and the track 5. Figure 4As shown, taking two inner rollers 64 and one outer roller 65 as an example, the two inner rollers 64 are symmetrically abutted against different positions of the inner wall of the track 5, and the outer roller 65 is abutted against the outer wall of the track 5, and the three form a stable triangular support structure; when the traction actuator 6 moves along the track 5, the triangularly distributed rollers evenly disperse the reaction force of the track 5 on the traction actuator 6 through multi-point contact, and each roller moves along the wall of the track 5 in the form of rolling friction, jointly constraining the radial displacement and deflection tendency of the traction actuator 6.

[0084] The triangularly distributed roller structure utilizes the principle of geometric stability to significantly improve the support stiffness and anti-overturning ability of the traction actuator 6 on the track 5. Even when the traction force direction changes or unbalanced load occurs during loading, the force balance effect of the triangular fulcrum can maintain the stable movement of the traction actuator 6. Compared with the traditional double-roller parallel distribution mode, the triangular distribution design can effectively reduce the shaking and deviation of the traction actuator 6.

[0085] In one embodiment, the traction mechanism includes a roller 66 and a traction motor 68. The roller 66 is rotatably arranged on the support frame 63. The traction rope 67 is wrapped around the surface of the roller 66. The free end of the traction rope 67 is suitable for being fixed to the blade 3. The traction motor 68 is connected to the roller 66. The roller 66 is configured to be driven by the traction motor 68 to apply traction to the blade 3 via the traction rope 67.

[0086] In this embodiment, when the traction motor 68 is energized, it drives the drum 66 to rotate on the support frame 63. The traction rope 67 wrapped around the surface of the drum 66 is wound or released as the drum 66 rotates, thereby changing the traction force exerted by the free end of the traction rope 67 on the blade 3. For example, when the drum 66 rotates in the forward direction, the traction rope 67 is wound and shortened, exerting a pulling force on the blade 3 toward the drum 66. When the drum 66 rotates in the reverse direction, the traction rope 67 is released and extended, maintaining a constant tension or reducing the tension according to the test requirements. The traction motor 68 achieves precise control of the speed and number of rotations through the control system, thereby precisely adjusting the extension and contraction of the traction rope 67 and achieving quantified output of the traction force. In this embodiment, the free end of the traction rope 67 is connected to the blade clamp 4 via a joint 69, and the joint 69 and the blade clamp 4 are connected in an articulated manner.

[0087] This traction mechanism, based on the winding principle of the drum 66, can achieve continuous adjustment and dynamic loading of the traction force through the precise control of the traction motor 68, meeting the requirements of different load amplitudes and frequencies in the fatigue test of the blade 3; the winding of the traction rope 67 and the drum 66 provides a stable force transmission path, and combined with the rigid support of the support frame 63, it can ensure that the application of the traction force has high linearity and repeatability; at the same time, the low friction characteristics of the rotation of the drum 66 and the servo control capability of the traction motor 68 enable the mechanism to quickly respond to the instructions of the control system, realize real-time adjustment of the traction force component in the multi-axis composite load of the blade 3, and provide a flexible and reliable power execution unit for simulating the complex stress state of the blade 3 in actual operation. Specifically, by changing the reciprocating frequency of the traction rope 67, the periodic loading of the fatigue load is achieved, and the traction frequency of each traction mechanism can be different.

[0088] In one embodiment, the track 5 is annular, and the number of the traction actuators 6 is at least three.

[0089] In this embodiment, the track 5 is annular (e.g., circular or elliptical), with three traction actuators 6 evenly or unevenly distributed along the track 5. During operation, the three traction actuators 6 independently move along the annular track 5 via their respective track displacement drive mechanisms, allowing for arbitrary circumferential position adjustment within a range of 0-360°. Simultaneously, the traction mechanism of each traction actuator 6 independently controls the magnitude and direction of the traction force. By coordinating the positions of the three traction actuators 6 and the traction forces (e.g., varying the pulling force amplitude and phase difference control), multi-directional composite loading can be achieved on the blade 3.

[0090] Furthermore, the number of the traction actuators 6 can also be four. The combination of the annular track 5 and the four traction actuators 6 provides a full circumferential loading coverage capability. Figure 5 To the attached Figure 7 ) can simulate the multi-directional coupled loads (such as the combined load of flapping, oscillation, and torsion) to which blade 3 is subjected in actual wind conditions. Compared to configurations with fewer than four actuators, four actuators can achieve more complex load path simulation through more flexible grouping and coordination (such as two groups of opposing loading, three groups of linkage, etc.). For example, two actuators in diagonal positions can simultaneously retract and release ropes to apply a torsional load, or the tension difference between three adjacent actuators can achieve coupled loading of oscillation and torsion. In addition, the multi-actuator redundant design improves system reliability. Even if a single actuator fails, the other actuators can still maintain some test functions, ensuring the continuity of fatigue testing and data integrity.

[0091] In one embodiment, the number of traction actuators 6 can also be as follows: Figure 8 Two are shown, or Figure 10 For one.

[0092] In one embodiment, the track support structure 1 is height-adjustable.

[0093] In this embodiment, the track support structure 1 can realize the lifting and lowering adjustment of the overall height of the track 5 through a built-in telescopic mechanism (such as a hydraulic telescopic rod, a screw nut pair, etc.) or a modular splicing structure; the operator can drive the telescopic mechanism to change the vertical height of the track support structure 1 through the control system or manual operation interface instructions according to the length, installation angle or test requirements of the blade 3 to be measured, so that the plane of the track 5 and the position to be loaded of the blade 3 are kept in the best adaptation state.

[0094] The height-adjustable design significantly improves the versatility and test adaptability of the device, and is compatible with the testing requirements of blades 3 of different models and sizes. For example, it can meet the low-position loading of small blades 3 and adapt to the high-position fatigue test of large blades 3. By precisely adjusting the height of the track 5, the connection point between the traction rope 67 and the blade clamp 4 can be ensured to be in the ideal force-bearing position, avoiding the traction force direction offset or additional bending moment caused by height deviation, thereby improving the accuracy of load simulation.

[0095] According to an embodiment of the present invention, on the other hand, a fatigue testing method based on a blade multi-degree-of-freedom traction loading device is provided, comprising the following steps:

[0096] Connect three traction actuators 6 to three different sides of the blade fixture 4, and adjust the positions of the three traction actuators 6 on the track 5 through the track displacement drive mechanism to form a predetermined spatial angle;

[0097] The traction mechanism that controls each traction actuator 6 applies periodic load to the blade 3 .

[0098] In this fatigue testing method, the working principle is as follows: first, three traction actuators 6 are connected to three different sides of the blade fixture 4 (for example, spaced 120 degrees apart circumferentially). The track displacement drive mechanism of each traction actuator 6 independently adjusts its circumferential position on the track 5, so that the traction directions of the three traction actuators 6 form a predetermined spatial angle to match the multi-directional load angles in the actual working conditions of the blade 3. Then, the traction mechanism of each traction actuator 6 is synchronously or asynchronously controlled by the control system to apply a periodic traction force to the blade 3 at a set frequency and load amplitude. For example, this can simulate an up-and-down reciprocating load in the blade 3's flapping direction, a back-and-forth reciprocating load in the shimmy direction, or a combined load of the two. The effect is that through the spatial position control and traction force coordinated loading of the three traction actuators 6, the multi-axial composite stress state that the blade 3 is subjected to during actual operation can be accurately simulated. Compared with the traditional uniaxial test mode that requires loading in different directions to be completed in stages, this method can realize the simultaneous application of multi-directional loads at one time, significantly shortening the test cycle; the setting of the predetermined spatial angle makes the load direction closer to the multi-directional force scenario under actual wind conditions, thereby improving the reliability of the fatigue test results. It is especially suitable for verifying the structural durability of the blade 3 under complex load coupling, and providing more comprehensive experimental data support for the design optimization of the blade 3.

[0099] In one embodiment, controlling the traction mechanism of each traction actuator 6 to apply periodic loading to the blade 3 includes: controlling the traction motor 68 of each traction actuator 6 to output a periodically varying length of the traction rope 67 to cause the test blade 3 to produce a three-axis coupled deformation.

[0100] In this embodiment, the control system controls the traction motors 68 of the three traction actuators 6 to output periodically varying rope lengths with specific phase differences. For example, when the rope of the first actuator contracts sinusoidally, the rope of the second actuator releases cosine-like, and the third actuator outputs a composite waveform with a specific phase angle relative to the first two. The coordinated changes in rope lengths of the three actuators create a spatial resultant force on the blade fixture 4, causing the blade 3 to simultaneously experience coupled deformations: flapping (vertical), oscillation (horizontal), and torsion (around the axis). For example, when two adjacent actuators synchronously retract and release their ropes, the blade 3 produces a flapping motion, while when the diagonal actuators operate asynchronously, a torsional component is superimposed.

[0101] 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 multi-degree-of-freedom traction loading device, characterized in that: include: A ground fixing assembly comprises a track support structure (1) and a blade base structure (2), wherein the blade base structure (2) supports the root of a blade (3) to be measured for fixing; a blade clamp (4), fixed to the blade (3); Multi-directional loading components, including: A track (5) fixed on the track support structure (1); at least one traction actuator (6) disposed on the track (5), and the traction actuator (6) is configured to be displaceable along the track (5); The traction actuator (6) comprises a track displacement drive mechanism and a traction mechanism; the traction actuator (6) is configured to move on the track (5) via the track displacement drive mechanism to change the traction direction of the blade (3) exerted by the traction actuator (6); the traction mechanism is connected to the blade clamp (4), and the traction mechanism is configured to apply an adjustable traction force to the blade (3).

2. The blade multi-degree-of-freedom traction loading device according to claim 1, characterized in that: The track displacement driving mechanism includes: a drive motor (61); A power gear (62) is fixed to the output shaft of the drive motor (61), and the power gear (62) is engaged with the meshing teeth on the track (5); The power gear (62) is configured to be driven by the drive motor (61) to drive the traction actuator (6) to move along the track (5).

3. The blade multi-degree-of-freedom traction loading device according to claim 2, characterized in that: The track displacement driving mechanism further includes: a supporting frame (63), the driving motor (61) being fixed to the supporting frame (63), and the power gear (62) being rotatably disposed on the supporting frame (63); The driven wheel group is movably connected to the support frame (63), and the driven wheel group is configured to provide support and limitation for the traction actuator (6).

4. The blade multi-degree-of-freedom traction loading device according to claim 3, characterized in that: The driven wheel set comprises: An inner roller (64) is movably connected to the support frame (63), and the inner roller (64) abuts against the inner wall of the track (5); The outer roller (65) is movably connected to the support frame (63), and the inner roller (64) abuts against the inner and outer side walls of the track (5); The inner roller (64) and the outer roller (65) are configured to support the traction actuator (6) on the track (5).

5. The blade multi-degree-of-freedom traction loading device according to claim 4, characterized in that: The number of the inner rollers (64) is at least two, or the number of the outer rollers (65) is at least two, and the three rollers are distributed in a triangular shape.

6. The blade multi-degree-of-freedom traction loading device according to claim 3, characterized in that: The traction mechanism comprises: A roller (66) is rotatably arranged on the support frame (63), a traction rope (67) is wound around the surface of the roller (66), and a free end of the traction rope (67) is suitable for being fixed to the blade (3); a traction motor (68) connected to the roller (66); The drum (66) is configured to be driven by the traction motor (68) to apply traction force to the blade (3) via the traction rope (67).

7. The blade multi-degree-of-freedom traction loading device according to any one of claims 1 to 6, characterized in that: The track (5) is ring-shaped, and the number of the traction actuators (6) is at least three.

8. The blade multi-degree-of-freedom traction loading device according to claim 7, characterized in that: The track support structure (1) is height-adjustable.

9. A fatigue testing method based on the blade multi-degree-of-freedom traction loading device according to claim 6, characterized in that: The steps include: Connecting three traction actuators (6) to three different sides of the blade fixture (4), and adjusting the positions of the three traction actuators (6) on the track (5) through the track displacement drive mechanism to form a predetermined spatial angle; The traction mechanism of each traction actuator (6) is controlled to apply periodic loading to the blade (3).

10. The fatigue testing method according to claim 9, characterized in that: The traction mechanism controlling each traction actuator (6) to apply periodic loading to the blade (3) comprises: The traction motor (68) of each traction actuator (6) is controlled to output a periodically changing length of the traction rope (67), so that the test blade (3) generates a three-axis coupled deformation.

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