A wind turbine blade torsional stiffness testing tool and method

Abstract

The application discloses a kind of wind turbine blade torsional rigidity test tool and test method, including column, horizontal slide rail, adjusting pulley block, clamping assembly, arc guide rail assembly, loading pulley block, loading device and traction rope, the column has two, symmetrically set in the left and right sides of blade to be measured, two columns are vertically connected with a horizontal slide rail on opposite sides, adjusting pulley block is installed on each horizontal slide rail, clamping assembly is set above between two columns, the left and right sides of clamping assembly are symmetrically connected with two arc guide rail assemblies, loading device is connected with loading pulley block, traction rope is set on loading pulley block, and its two ends are vertically extended downward, one end is connected with the bottom end of lower arc guide rail assembly, and the other end is sequentially passed through two adjusting pulley blocks and connected to the top end of another arc guide rail assembly.The application can effectively improve the accuracy of wind turbine blade torsional rigidity test.

Description

Technical Field

[0001] This invention relates to the technical field of wind turbine blade torsional stiffness testing, and in particular to a testing fixture and method for wind turbine blade torsional stiffness testing. Background Technology

[0002] As the length of wind turbine blades increases, the flapping and swaying deformations during operation become greater, and the aerodynamic loads perpendicular to the blade deformation direction cause the blades to bear more torque. The aeroelastic response of wind turbine blades is highly sensitive to torsional stiffness. Accurate measurement of the torsional stiffness of wind turbine blades is of great significance for predicting blade aeroelastic divergence and accurately analyzing the blade structural strength.

[0003] The existing testing method involves fixing the blade root to a test bench, installing a test fixture on the blade's loading section, and applying a pair of force couples on both sides of the test fixture to induce torsion in the blade. The torsional stiffness is then calculated by measuring the torsional angle of the loading section. The distance between the two force loading points on the test fixture is called the lever arm. When the force loading points are fixedly connected to the test fixture, if the direction of the loading force remains unchanged, the lever arm will change as the loading section rotates.

[0004] In existing testing methods, when two load drivers apply loads in opposite directions to the test fixture, it is difficult to ensure that the output loads of the two load drivers are equal, thus introducing other loads and making the load on the blade loading section not a pure torque.

[0005] The blade tip has a pre-bent structure, and the blade stiffness decreases from the root to the tip. This causes the loaded section to not only rotate around the shear center when torque is applied in the tip region, but also to displace in other directions. In existing testing methods, the hinge between the test fixture and the loading drive affects the free movement of the loaded section, introducing too many constraints and thus affecting the test accuracy. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a testing fixture for the torsional stiffness of wind turbine blades, which can effectively improve the accuracy of wind turbine blade torsional stiffness testing.

[0007] Another objective of this invention is to provide a method for testing the torsional stiffness of wind turbine blades.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A testing fixture for the torsional stiffness of a wind turbine blade includes two columns, horizontal slide rails, adjusting pulley blocks, clamping components, arc-shaped guide rail components, loading pulley blocks, a loading device, a force sensor, a traction rope, and a driving device. Two columns are symmetrically arranged on the left and right sides of the blade under test. A horizontal slide rail is vertically connected to the opposite sides of each column, and an adjusting pulley block is installed on each horizontal slide rail. The clamping component is positioned above the two columns and is used to clamp the blade under test. It can be replaced according to different loading sections of the blade. Two arc-shaped guide rail components are symmetrically connected to the left and right sides of the clamping component. The arc structures of the two arc-shaped guide rail components are concentric, and each arc-shaped guide rail component is located above two adjusting pulley blocks. The loading pulley blocks are positioned on the clamping component according to the loading direction requirements. The loading device is located to the left or right of the blade and directly above the left or right adjusting pulley group. It is connected to the loading pulley group and is used to apply an upward pulling force. A force sensor is set between the loading device and the loading pulley group to record the pulling force value applied by the loading device. The traction rope is set on the loading pulley group, with its two ends extending vertically downward. One end is connected to the bottom end of the lower arc-shaped guide rail assembly, and the other end passes around two adjusting pulley groups in sequence and is connected to the top end of another arc-shaped guide rail assembly. The tension on the traction rope is converted into a tangential load through the two arc-shaped guide rail assemblies, forming a pair of force couples on both sides of the blade to be tested. Each adjusting pulley group is connected to a driving device, which drives the corresponding adjusting pulley group to move horizontally along the horizontal slide rail to adjust the verticality of the vertical part of the traction rope to the ground.

[0010] Furthermore, the clamping assembly includes a left pad, a right pad, a left bracket, a right bracket, an upper bracket, a lower bracket, and long bolts. The left and right brackets are symmetrically arranged, and their tops and bottoms are connected by long bolts. The left pad is bolted to the left bracket, and the right pad is bolted to the right bracket. The opposite sides of the left and right pads each have curved surfaces adapted to the loading cross-section of the blade under test. The upper bracket is bolted to the top of the left and right brackets, and the lower bracket is bolted to the bottom of the left and right brackets. Multiple adjustment holes for connecting to the arc-shaped guide rail assembly are machined on the left and right sides of the upper and lower brackets. The spacing between the adjustment holes on the left and right sides of each bracket is greater than the thickness of the loading cross-section of the blade under test, and the spacing between the adjustment holes on the same side of the two brackets is greater than the chord length of the loading cross-section of the blade under test.

[0011] Furthermore, the arc-shaped guide rail assembly includes an arc-shaped guide rail and two diagonal brace assemblies. The upper and lower sides of the arc-shaped guide rail are respectively machined with multiple diagonal brace adjustment holes for connecting with the diagonal brace assemblies. The two diagonal brace assemblies are symmetrically arranged on the upper and lower sides of the arc-shaped guide rail. The outer surface of the arc-shaped guide rail has an arc structure. The top and bottom ends of the arc structure are respectively provided with fixing holes for installing traction ropes. A groove for limiting the traction rope is provided on the arc structure between the two fixing holes. The diagonal brace assembly includes a first diagonal brace and a second diagonal brace.

[0012] The first diagonal brace has multiple first adjustment holes machined at both ends. The first diagonal brace is connected to the clamping assembly and the arc-shaped guide rail respectively through the first adjustment holes at both ends. The second diagonal brace has multiple second adjustment holes machined at both ends. The second diagonal brace is connected to the first diagonal brace and the arc-shaped guide rail respectively through the second adjustment holes at both ends. The second diagonal brace restricts the relative rotation between the arc-shaped guide rail and the first diagonal brace to prevent deformation of the test fixture. At the same time, by adjusting the installation combination of the first adjustment holes, the second adjustment holes and the diagonal brace adjustment holes, the hole spacing between the two first diagonal braces can be changed, so that the arc-shaped guide rail assembly can be installed on the clamping assembly at different heights.

[0013] Furthermore, the diameter of the arc structure is greater than the maximum thickness of the blade loading section profile, and the angle between the upper and lower ends of the arc structure and the center of the arc structure is 20° to 30°, so as to ensure that when the blade loading section rotates within a range of ±10°, the traction rope can be confined inside the groove and remain tangent to the arc structure.

[0014] Furthermore, the adjusting pulley assembly includes a first bracket, a first pulley, a second bracket, and a second pulley. The first bracket has an H-shaped structure. The first pulley and the second pulley are respectively mounted on the upper and lower sides of the first bracket via pins. The first pulley is mounted on a horizontal slide rail, and a groove for limiting the traction rope is machined on the outer circumference of the first pulley. The second bracket has a Y-shaped structure, with one end connected to the bottom of the first bracket and the other end connected to a driving device. The driving device is mounted on a column and drives the second pulley, thereby moving the adjusting pulley assembly along the horizontal slide rail.

[0015] Furthermore, the loading pulley assembly includes a third pulley and a third bracket. The third bracket has an inverted U-shaped structure. The third pulley is mounted on the third bracket via a pin. The outer circumferential surface of the third pulley is machined with a groove for limiting the traction rope. The top of the third bracket is machined with a mounting position for mounting a force sensor.

[0016] Furthermore, a rail brace is provided at the bottom of the horizontal slide rail, with one end of the rail brace connected to the horizontal slide rail and the other end connected to the column.

[0017] Furthermore, detection marks are respectively set on the vertical sections of the traction rope between the loading pulley group and the adjusting pulley group, the vertical sections between the loading pulley group and the arc-shaped guide rail assembly, and the vertical sections between the adjusting pulley group and the arc-shaped guide rail assembly. The perpendicularity of the corresponding section of the traction rope to the ground is calculated by measuring the coordinate values ​​of the detection marks.

[0018] Another objective of this invention is achieved through the following technical solution:

[0019] A method for testing the torsional stiffness of wind turbine blades, using the aforementioned testing fixture, includes the following steps.

[0020] S1. Make the chord length of the blade to be tested vertical, fix the root of the blade to be tested on the test table, and fix the loading section of the blade to be tested on the clamping assembly.

[0021] S2. Marking points are set at equal intervals on the center line of the main beam of the blade to be tested, and an inclinometer is installed at each marking point. Detection marks are set on the vertical part of the traction rope between the loading pulley group and the adjusting pulley group, the vertical part between the loading pulley group and the arc guide rail assembly, and the vertical part between the adjusting pulley group and the arc guide rail assembly.

[0022] S3. In the initial state, the loading pulley block and loading device are located on the left side of the clamping assembly. All force sensors are zeroed in the initial equilibrium state. The loading device applies an upward pulling force, and the traction rope drives the blade to be tested to rotate clockwise. The loading device loads in multiple stages according to the preset ratio of the target torque. After each stage of loading, the coordinates of three sets of detection marks are detected, and the verticality of the three vertical parts of the traction rope relative to the ground is calculated. The pulley block is adjusted to move horizontally through two drive devices to keep the vertical parts of the traction rope vertical. Then, it is kept vertical for a preset time, and the pulling force F applied by the loading device and the arc difference θ between two adjacent mark points are recorded.

[0023] S4. Repeat step S3 to load the preset number of times to obtain multiple sets of tension F and radii θ data under clockwise loading test of the blade under test.

[0024] S5. Adjust the traction rope, loading pulley block and loading device. Set the loading pulley block and loading device to the right side of the clamping assembly. Zero all sensors in the initial equilibrium state. Apply an upward pulling force using the loading device. The traction rope drives the blade to be tested to rotate counterclockwise. The loading device loads in multiple stages according to the preset ratio of the target torque. After each stage of loading, detect the coordinates of three sets of detection marks and calculate the verticality of the three vertical parts of the traction rope relative to the ground. Use two drive devices to pull and adjust the pulley block to move horizontally so that the vertical parts of the traction rope remain vertical. Then maintain the verticality for a preset time and record the pulling force F′ applied by the loading device and the arc difference θ′ between two adjacent mark points.

[0025] S6. Repeat step S5 to load the preset number of times to obtain multiple sets of tension F′ and radian difference θ′ data under counterclockwise loading test of the blade under test;

[0026] S7. Calculate the torsional stiffness G of the blade segment between two adjacent marked points under clockwise loading test based on the data recorded in step S4. j Based on the data recorded in step S6, calculate the torsional stiffness G′ of the blade segment between two adjacent marked points under counterclockwise loading test. j The torsional stiffness G of each leaf segment j and torsional stiffness G′ j The average value is taken as the final torsional stiffness of the leaf segment.

[0027] Furthermore, based on the data recorded in step S4, the torsional stiffness G of the blade segment between two adjacent marked points under clockwise loading test is calculated. j ,

[0028]

[0029] Where F is the tensile force applied by the loading device under clockwise loading test, R is the radius of the arc structure of the arc guide rail assembly, L is the distance between the two marking points, and θ is the difference in radii between two adjacent marking points on the blade under test.

[0030] Based on the data recorded in step S6, calculate the torsional stiffness G′ of the blade segment between any two adjacent marked points under counterclockwise loading test. j ,

[0031]

[0032] Where F′ is the tensile force applied by the loading device under counterclockwise loading test, R is the radius of the arc structure of the arc guide rail assembly, L is the distance between the two marking points, and θ′ is the difference in radii between two adjacent marking points on the blade under test;

[0033] The torsional stiffness G of each leaf segment j and torsional stiffness G′ j The average value is taken as the final torsional stiffness of the leaf segment.

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

[0035] 1. When the test fixture of the present invention is used, the traction rope is restricted by the groove of the arc-shaped guide rail when the blade loading section is rotated by torque, and is always tangent to the arc structure of the arc-shaped guide rail. The distance from the tangent point to the center of the arc structure is the lever arm. This lever arm will not change with the rotation of the loading section, which can effectively improve the accuracy of the torsional stiffness test of wind turbine blades.

[0036] 2. Using the test fixture of the present invention, the forces on the traction ropes on both sides of the loading pulley block are equal, and the forces transmitted by the traction ropes to the arc-shaped guide rails on the left and right sides of the test fixture are equal (the loading forces on both sides of the test fixture are equal), thus avoiding the introduction of other loads.

[0037] 3. The test fixture of the present invention applies torque to the blade only through a flexible traction rope, and does not restrict the movement of the blade loading section in other directions in space.

[0038] 4. The test fixture of the present invention is lightweight, easy to install and disassemble, and has good versatility. When it is necessary to test other cross-sectional positions of the blade, only the clamping component needs to be replaced. Then, by adjusting the mounting hole combination of the arc guide rail, the first inclined brace, and the second inclined brace, the arc guide rail component is connected to the clamping component and the load test is performed. It is highly practical. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the test fixture of the present invention.

[0040] Figure 2 This is a schematic diagram of the clamping assembly of the present invention.

[0041] Figure 3 This is a schematic diagram of the arc-shaped guide rail assembly of the present invention.

[0042] Figure 4 This is a schematic diagram of the arc-shaped guide rail of the present invention.

[0043] Figure 5 This is a schematic diagram of the structure of the first diagonal brace of the present invention.

[0044] Figure 6 This is a schematic diagram of the structure of the second diagonal brace of the present invention.

[0045] Figure 7 This is a schematic diagram of the adjusting pulley system of the present invention.

[0046] Figure 8 This is a schematic diagram of the loading pulley system of the present invention.

[0047] Figure 9 This is a schematic diagram of a torsional stiffness test performed using the test fixture of the present invention.

[0048] Figure 10This is a schematic diagram of a counterclockwise loading test performed using the test fixture of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0050] Example 1:

[0051] like Figure 1 As shown, this embodiment provides a testing fixture for the torsional stiffness of a wind turbine blade, including a column 1, a horizontal slide rail 2, an adjusting pulley block 3, a clamping assembly 4, an arc-shaped guide rail assembly 5, a loading pulley block 6, a loading device 7, a force sensor 8, a traction rope 9, and a driving device 10. There are two columns 1, symmetrically arranged on the left and right sides of the blade 12 to be tested. A horizontal slide rail 2 is vertically connected to the opposite sides of each column 1. An adjusting pulley block 3 is installed on each horizontal slide rail 2. The clamping assembly 4 is located above the space between the two columns 1, used to clamp the blade 12 to be tested, and can be replaced according to the different loading sections of the blade. Two arc-shaped guide rail assemblies 5 are symmetrically connected to the left and right sides of the clamping assembly 4. The arc structures 502 of the two arc-shaped guide rail assemblies 5 are concentric, and the two arc-shaped guide rail assemblies 5 are respectively located above the two adjusting pulley blocks 3. The loading pulley block 6 is arranged on the left side of the clamping assembly 4 according to the loading direction requirements. The loading device 7 is located on the side or right side, and directly above the left or right adjusting pulley group 3. It is connected to the loading pulley group 6 and is used to apply an upward pulling force. The loading device 7 can be a crane, hoist, or other device. A force sensor 8 is set between the loading device 7 and the loading pulley group 6 to record the pulling force value applied by the loading device 7. The traction rope 9 is set on the loading pulley group 6, with its two ends extending vertically downward. One end is connected to the bottom end of the lower arc-shaped guide rail assembly 5, and the other end passes around two adjusting pulley groups 3 in sequence and is connected to the top end of another arc-shaped guide rail assembly 5. The tension on the traction rope 9 is converted into a tangential load through the two arc-shaped guide rail assemblies 5, forming a pair of force couples on both sides of the blade 12 to be tested. Each adjusting pulley group 3 is connected to a driving device 10. The driving device 10 drives the corresponding adjusting pulley group 3 to move horizontally along the horizontal slide rail 2 to adjust the verticality of the vertical part of the traction rope 9 to the ground.

[0052] like Figure 2As shown, the clamping assembly 4 includes a left pad 401, a right pad 402, a left bracket 403, a right bracket 404, an upper bracket 405, a lower bracket 406, and a long bolt 407. The left bracket 403 and the right bracket 404 are arranged symmetrically from left to right. The top and bottom of the left bracket 403 and the right bracket 404 are connected by the long bolt 407. The left pad 401 is bolted to the left bracket 403, and the right pad 402 is bolted to the right bracket 404. The opposite sides of the left pad 401 and the right pad 402 are respectively formed with a loading cross section corresponding to the blade 12 to be tested. The upper bracket 405 is bolted to the top of the left bracket 403 and the right bracket 404, and the lower bracket 406 is bolted to the bottom of the left bracket 403 and the right bracket 404. The upper bracket 405 and the lower bracket 406 are respectively machined with multiple adjustment holes 408 for connecting with the arc-shaped guide rail assembly 5 on the left and right sides. The hole spacing T of the adjustment holes 408 on the left and right sides of each bracket is greater than the thickness of the loading section of the blade 12 to be tested. The hole spacing H between the adjustment holes 408 on the same side of the two brackets is greater than the chord length of the loading section of the blade 12 to be tested.

[0053] like Figures 3 to 6 As shown, the arc-shaped guide rail assembly 5 includes an arc-shaped guide rail 501 and two inclined support assemblies. Multiple inclined support adjustment holes 5011 for connecting to the inclined support assemblies are machined on the upper and lower sides of the arc-shaped guide rail 501. The two inclined support assemblies are symmetrically arranged on the upper and lower sides of the arc-shaped guide rail 501. The outer surface of the arc-shaped guide rail 501 is an arc structure 502. Fixing holes 5021 for installing the traction rope 9 are respectively provided at the top and bottom ends of the arc structure 502. A groove 5022 for limiting the traction rope 9 is provided on the arc structure 502 and between the two fixing holes 5021. The inclined support assembly includes a first inclined support 503 and a second inclined support 504. Multiple first adjustment holes 5031 are machined at both ends of the first inclined support 503. A first inclined brace 503 is connected to the clamping assembly 4 and the arc-shaped guide rail 501 respectively through the first adjustment holes 5031 at both ends. The second inclined brace 504 has multiple second adjustment holes 5041 machined at both ends. The second inclined brace 504 is connected to the first inclined brace 503 and the arc-shaped guide rail 501 respectively through the second adjustment holes 5041 at both ends. The second inclined brace 504 restricts the relative rotation between the arc-shaped guide rail 501 and the first inclined brace 503 to prevent deformation of the test fixture. At the same time, by adjusting the installation combination of the first adjustment hole 5031, the second adjustment hole 5041 and the inclined brace adjustment hole 5011, the hole spacing H1 between the two first inclined braces 503 can be changed, so that the arc-shaped guide rail assembly 5 can be installed on the clamping assembly 4 at different heights.

[0054] Furthermore, the diameter of the arc structure 502 is greater than the maximum thickness of the blade loading section profile, and the angle α between its upper and lower ends and the line connecting the center O of the arc structure 502 is about 20° to 30°, so as to ensure that when the blade loading section rotates within a range of ±10°, the traction rope 9 can be confined inside the groove 5022 and remain tangent to the arc structure 502.

[0055] like Figure 7 As shown, the adjusting pulley assembly 3 includes a first bracket 301, a first pulley 302, a second bracket 303, and a second pulley 304. The first bracket 301 has an H-shaped structure. The first pulley 302 and the second pulley 304 are respectively mounted on the upper and lower sides of the first bracket 301 by pins. The first pulley 302 is set on the horizontal slide rail 2, and a groove 3021 for limiting the traction rope 9 is machined on the outer circumference of the first pulley 302. The second bracket 303 has a Y-shaped structure. One end of its structure is connected to the bottom of the first bracket 301, and the other end is connected to the drive device 10. The drive device 10 is mounted on the column 1. The drive device 10 drives the second pulley 304 and drives the adjusting pulley assembly 3 to move along the horizontal slide rail 2.

[0056] like Figure 8 As shown, the loading pulley block 6 includes a third pulley 601 and a third bracket 602. The third bracket 602 has an inverted U-shaped structure. The third pulley 601 is mounted on the third bracket 602 by a pin. The outer circumferential surface of the third pulley 601 is machined with a groove 6011 for limiting the traction rope 9. The top of the third bracket 602 is machined with a mounting position 603 for mounting the force sensor 8.

[0057] The bottom of the horizontal slide rail 2 is provided with a slide rail brace 11. One end of the slide rail brace 11 is connected to the horizontal slide rail 2, and the other end is connected to the column 1. The column 1, the horizontal slide rail 2 and the slide rail brace 11 form a stable triangle, which can reduce the deformation of the slide rail under stress.

[0058] The traction rope 9 is equipped with detection marks on the vertical sections I-II between the loading pulley block 6 and the adjusting pulley block 3, the vertical sections III-IV between the loading pulley block 6 and the arc-shaped guide rail assembly 5, and the vertical sections V-VI between the adjusting pulley block 3 and the arc-shaped guide rail assembly 5. The coordinates of the detection marks can be detected by optical equipment such as a total station. The perpendicularity of the corresponding section of the traction rope 9 to the ground is calculated by measuring the coordinate values ​​of the detection marks.

[0059] Example 2:

[0060] like Figure 9 As shown, this embodiment provides a method for testing the torsional stiffness of wind turbine blades, using the wind turbine blade torsional stiffness testing fixture described in Embodiment 1, including the following steps:

[0061] S1. Make the chord length of the blade to be tested 12 vertical, fix the root of the blade to be tested 12 on the test bench 13, and fix the loading section of the blade to be tested on the clamping assembly 4.

[0062] S2. Marking points A, B, C, D, and E are set at equal intervals on the center line 14 of the main beam of the blade to be tested, and an inclinometer 15 is installed at each marking point. The distance L between two marking points is 4 to 5 meters. Detection marks are set on the vertical sections I-II between the loading pulley group and the adjusting pulley group, the vertical sections III-IV between the loading pulley group and the arc-shaped guide rail assembly, and the vertical sections V-VI between the adjusting pulley group and the arc-shaped guide rail assembly, respectively.

[0063] S3. In the initial state, the loading pulley block and loading device are located on the left side of the clamping assembly. All force sensors are zeroed in the initial equilibrium state. The loading device applies an upward pulling force, and the traction rope drives the blade to be tested to rotate clockwise. The loading device loads in three levels according to 50%, 80%, and 100% of the target torque. After each level of loading, the coordinates of three sets of detection marks are detected, and the verticality of the three vertical parts of the traction rope relative to the ground is calculated. The pulley block is adjusted to move horizontally through two drive devices to keep the vertical parts of the traction rope vertical. Then, it is kept for 5 to 10 minutes to stabilize the values ​​of the force sensor and inclinometer. The pulling force F applied by the loading device and the arc difference θ between two adjacent marks are recorded, namely the arc difference between marks A and B, marks B and C, marks C and D, and marks D and E.

[0064] S4. Repeat step S3 three times to obtain multiple sets of tension F and radii θ data under clockwise loading test of the blade under test.

[0065] S5, such as Figure 10 As shown, adjust the traction rope, loading pulley group, and loading device. Set the loading pulley group and loading device to the right side of the clamping assembly. Zero all sensors in the initial equilibrium state. Apply an upward pulling force using the loading device. The traction rope drives the blade to be tested to rotate counterclockwise. The loading device loads in multiple stages according to the preset ratio of the target torque. After each stage of loading, detect the coordinates of three sets of detection marks and calculate the verticality of the three vertical parts of the traction rope relative to the ground. Move the adjusting pulley group horizontally through two drive devices to keep the vertical parts of the traction rope vertical. Then maintain this position for 5 to 10 minutes to stabilize the values ​​of the force sensor and inclinometer. Record the pulling force F′ applied by the loading device and the arc difference θ′ between any two adjacent marks, i.e., the arc difference between mark point A and mark point B, the arc difference between mark point B and mark point C, the arc difference between mark point C and mark point D, and the arc difference between mark point D and mark point E.

[0066] S6. Repeat step S5 three times to obtain multiple sets of tension F′ and radian difference θ′ data under counterclockwise loading test of the blade under test.

[0067] S7. Calculate the torsional stiffness G of the blade segments (i.e., segments AB, BC, CD, and DE) between adjacent marked points under clockwise loading test based on the data recorded in step S4. j ,

[0068]

[0069] Where F is the tensile force applied by the loading device under clockwise loading test, R is the radius of the arc structure of the arc guide rail assembly, L is the distance between the two marking points, and θ is the difference in radii between two adjacent marking points on the blade under test.

[0070] Based on the data recorded in step S6, calculate the torsional stiffness G′ of the blade segments (i.e., segments AB, BC, CD, and DE) between two adjacent marked points under counterclockwise loading test. j ,

[0071]

[0072] Where F′ is the tensile force applied by the loading device under counterclockwise loading test, R is the radius of the arc structure of the arc guide rail assembly, L is the distance between the two marking points, and θ′ is the difference in radii between two adjacent marking points on the blade under test;

[0073] The torsional stiffness G of each leaf segment j and torsional stiffness G′ j The average value is taken as the final torsional stiffness of the leaf segment.

[0074] When it is necessary to test other loading section positions of the blade, simply replace the clamping component with one suitable for the loading section surface, clamp the clamping component at the loading section position, and repeat the above steps S1 to S7 to complete the calculation of the blade torsional stiffness.

[0075] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A method for testing the torsional stiffness of wind turbine blades, characterized in that: A torsional stiffness testing fixture for wind turbine blades is used. The fixture includes columns, horizontal slide rails, adjusting pulley blocks, clamping components, arc-shaped guide rail components, loading pulley blocks, a loading device, a force sensor, a traction rope, and a drive device. Two columns are symmetrically positioned on the left and right sides of the blade under test. A horizontal slide rail is vertically connected to the opposite sides of each column, and an adjusting pulley block is mounted on each horizontal slide rail. The clamping component is positioned above the two columns to clamp the blade under test and can be replaced according to the different loading sections of the blade. Two arc-shaped guide rail components are symmetrically connected to the left and right sides of the clamping component. The arc structures of the two arc-shaped guide rail components are concentric, and each arc-shaped guide rail component is located above two adjusting pulley blocks. The loading pulley blocks are positioned according to the loading direction requirements. The loading device is located on the left or right side of the component and directly above the left or right adjusting pulley group. The loading device is connected to the loading pulley group to apply an upward pulling force. A force sensor is set between the loading device and the loading pulley group to record the pulling force value applied by the loading device. The traction rope is set on the loading pulley group, with its two ends extending vertically downward. One end is connected to the bottom end of the lower arc-shaped guide rail component, and the other end passes around two adjusting pulley groups in sequence and is connected to the top end of another arc-shaped guide rail component. The two arc-shaped guide rail components convert the tension on the traction rope into a tangential load, forming a pair of force couples on both sides of the blade to be tested. Each adjusting pulley group is connected to a driving device, which drives the corresponding adjusting pulley group to move horizontally along the horizontal slide rail to adjust the verticality of the vertical part of the traction rope to the ground. The test method includes the following steps: S1. Make the chord of the blade to be tested vertical, fix the root of the blade to be tested on the test table, and fix the loading section of the blade to be tested on the clamping assembly. S2. Marking points are set at equal intervals on the center line of the main beam of the blade to be tested, and an inclinometer is installed at each marking point. Detection marks are set on the vertical part of the traction rope between the loading pulley group and the adjusting pulley group, the vertical part between the loading pulley group and the arc guide rail assembly, and the vertical part between the adjusting pulley group and the arc guide rail assembly. S3. In the initial state, the loading pulley block and loading device are located on the left side of the clamping assembly. All force sensors are zeroed in the initial equilibrium state. The loading device applies an upward pulling force, and the traction rope drives the blade to be tested to rotate clockwise. The loading device loads in multiple stages according to the preset ratio of the target torque. After each stage of loading, the coordinates of three sets of detection marks are detected, and the verticality of the three vertical parts of the traction rope relative to the ground is calculated. The pulley block is adjusted to move horizontally through two drive devices to keep the vertical parts of the traction rope vertical. Then, it is kept vertical for a preset time, and the pulling force F applied by the loading device and the arc difference θ between two adjacent mark points are recorded. S4. Repeat step S3 to load the preset number of times to obtain multiple sets of tension F and radii θ data under clockwise loading test of the blade under test. S5. Adjust the traction rope, loading pulley block and loading device. Set the loading pulley block and loading device to the right side of the clamping assembly. Zero all sensors in the initial equilibrium state. Apply an upward pulling force using the loading device. The traction rope drives the blade to be tested to rotate counterclockwise. The loading device loads in multiple stages according to the preset ratio of the target torque. After each stage of loading, detect the coordinates of three sets of detection marks and calculate the verticality of the three vertical parts of the traction rope relative to the ground. Use two drive devices to pull and adjust the pulley block to move horizontally so that the vertical parts of the traction rope remain vertical. Then maintain the verticality for a preset time and record the pulling force F′ applied by the loading device and the arc difference θ′ between two adjacent mark points. S6. Repeat step S5 to load the preset number of times to obtain multiple sets of tension F′ and radian difference θ′ data under counterclockwise loading test of the blade under test; S7. Calculate the torsional stiffness G of the blade segment between two adjacent marked points under clockwise loading test based on the data recorded in step S4. j Based on the data recorded in step S6, calculate the torsional stiffness G′ of the blade segment between two adjacent marked points under counterclockwise loading test. j The torsional stiffness G of each leaf segment j and torsional stiffness G′ j The average value is taken as the final torsional stiffness of the leaf segment.

2. The method for testing the torsional stiffness of wind turbine blades according to claim 1, characterized in that: The clamping assembly includes a left pad, a right pad, a left bracket, a right bracket, an upper bracket, a lower bracket, and long bolts. The left and right brackets are symmetrically arranged, and their tops and bottoms are connected by long bolts. The left pad is bolted to the left bracket, and the right pad is bolted to the right bracket. The opposite sides of the left and right pads each have curved surfaces adapted to the loading cross-section of the blade under test. The upper bracket is bolted to the top of the left and right brackets, and the lower bracket is bolted to the bottom of the left and right brackets. Multiple adjustment holes for connecting to the arc-shaped guide rail assembly are machined on the left and right sides of each bracket. The spacing between the adjustment holes on the left and right sides of each bracket is greater than the thickness of the loading cross-section of the blade under test, and the spacing between the adjustment holes on the same side of the two brackets is greater than the chord length of the loading cross-section of the blade under test.

3. The method for testing the torsional stiffness of wind turbine blades according to claim 1, characterized in that: The arc-shaped guide rail assembly includes an arc-shaped guide rail and two diagonal brace assemblies. The upper and lower sides of the arc-shaped guide rail are respectively machined with multiple diagonal brace adjustment holes for connection with the diagonal brace assemblies. The two diagonal brace assemblies are symmetrically arranged on the upper and lower sides of the arc-shaped guide rail. The outer surface of the arc-shaped guide rail is an arc structure. The top and bottom ends of the arc structure are respectively provided with fixing holes for installing traction ropes. A groove for limiting the traction rope is provided on the arc structure between the two fixing holes. The diagonal brace assembly includes a first diagonal brace and a second diagonal brace. Multiple first diagonal brace adjustment holes are machined at both ends of the first diagonal brace. The first diagonal brace is connected to the clamping assembly and the arc-shaped guide rail respectively through the first adjustment holes at both ends. The second diagonal brace has multiple second adjustment holes at both ends. The second diagonal brace is connected to the first diagonal brace and the arc-shaped guide rail respectively through the second adjustment holes at both ends. The second diagonal brace restricts the relative rotation between the arc-shaped guide rail and the first diagonal brace to prevent deformation of the test fixture. At the same time, by adjusting the installation combination of the first adjustment holes, the second adjustment holes and the diagonal brace adjustment holes, the hole spacing between the two first diagonal braces can be changed, so that the arc-shaped guide rail assembly can be installed on the clamping assembly at different heights.

4. The method for testing the torsional stiffness of wind turbine blades according to claim 3, characterized in that: The diameter of the arc structure is greater than the maximum thickness of the blade loading section profile. The angle between the upper and lower ends of the arc structure and the center of the arc structure is 20° to 30°, so as to ensure that when the blade loading section rotates within a range of ±10°, the traction rope can be limited inside the groove and remain tangent to the arc structure.

5. The method for testing the torsional stiffness of wind turbine blades according to claim 1, characterized in that: The adjusting pulley assembly includes a first bracket, a first pulley, a second bracket, and a second pulley. The first bracket has an H-shaped structure. The first pulley and the second pulley are respectively mounted on the upper and lower sides of the first bracket via pins. The first pulley is mounted on a horizontal slide rail, and a groove for limiting the traction rope is machined on the outer circumference of the first pulley. The second bracket has a Y-shaped structure, with one end connected to the bottom of the first bracket and the other end connected to a driving device. The driving device is mounted on a column and drives the second pulley, thereby moving the adjusting pulley assembly along the horizontal slide rail.

6. The method for testing the torsional stiffness of wind turbine blades according to claim 1, characterized in that: The loading pulley assembly includes a third pulley and a third bracket. The third bracket has an inverted U-shaped structure. The third pulley is mounted on the third bracket by a pin. The outer circumferential surface of the third pulley is machined with a groove for limiting the traction rope. The top of the third bracket is machined with a mounting position for mounting a force sensor.

7. The method for testing the torsional stiffness of wind turbine blades according to claim 1, characterized in that: The bottom of the horizontal slide rail is provided with a slide rail brace, one end of which is connected to the horizontal slide rail and the other end is connected to the column.

8. The method for testing the torsional stiffness of wind turbine blades according to claim 1, characterized in that: The traction rope is equipped with detection marks on the vertical sections between the loading pulley group and the adjusting pulley group, the vertical sections between the loading pulley group and the arc-shaped guide rail assembly, and the vertical sections between the adjusting pulley group and the arc-shaped guide rail assembly. The perpendicularity of the corresponding section of the traction rope to the ground is calculated by measuring the coordinate values ​​of the detection marks.

9. The method for testing the torsional stiffness of wind turbine blades according to claim 1, characterized in that, Based on the data recorded in step S4, calculate the torsional stiffness G of the blade segment between any two adjacent marked points under clockwise loading test. j , Where F is the tensile force applied by the loading device under clockwise loading test, R is the radius of the arc structure of the arc guide rail assembly, L is the distance between the two marking points, and θ is the difference in radii between two adjacent marking points on the blade under test. Based on the data recorded in step S6, calculate the torsional stiffness G′ of the blade segment between any two adjacent marked points under counterclockwise loading test. j , Where F′ is the tensile force applied by the loading device under counterclockwise loading test, R is the radius of the arc structure of the arc guide rail assembly, L is the distance between the two marking points, and θ′ is the difference in radii between two adjacent marking points on the blade under test; The torsional stiffness G of each leaf segment j and torsional stiffness G′ j The average value is taken as the final torsional stiffness of the leaf segment.

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