Variable bending moment loading device for wind power blade trailing edge buckling test and bending moment calculation method

Abstract

The invention belongs to the field of wind power blade part testing, and particularly relates to a variable bending moment loading device for a wind power blade trailing edge buckling test and a bending moment calculation method. The trailing edge buckling loading device is characterized by comprising a cast iron platform, a force application device, a steel structure tool, a clamping device, a control system and a data acquisition system. The section of the wind power blade is fixed to a loading force arm of the steel structure tool through a wood clamping plate, the hydraulic cylinders on the two sides drive the corresponding cantilevers to apply bending moments to the two sides of a sample piece under the action of a control system, and finally the section generates preset buckling failure at the preset position of the rear edge area of the section. And the data acquisition system records bending moment force, deformation and surface strain data of the sample piece, so that the buckling resistance of the section of the wind power blade is analyzed. By using the loading device and the bending moment calculation method provided by the invention, the mechanical property of the section of the wind power blade can be accurately measured, and the bearing capacity of the section on the complete blade can be calculated.

Description

Technical Field

[0001] The invention belongs to the field of static loading test of wind turbine blades, and in particular relates to a loading device and a bending moment calculation method for component-level trailing edge buckling test of wind turbine blades. Background Art

[0002] Wind turbine blades are the main components for converting wind energy into electricity. The use of composite materials and optimized structural design play a great role in their stable operation. At present, the phenomenon of trailing edge buckling failure is one of the main reasons for the collapse of blade structures on land and at sea, and the swing load caused by the blade's own weight and torsional bending moment is the most important factor. In full-scale tests, when swing loading is performed, the damage to blade components is mostly concentrated in the middle and rear sections of the blade. Therefore, the structural performance of the trailing edge section represents the structural strength of the entire blade to a certain extent. However, the full-scale test has a long test cycle, high manpower and cost costs, and the full-scale test tests the structure of the entire blade rather than a specific failure type, making it difficult to conduct a deeper failure mechanism study on the buckling performance of the blade trailing edge. Therefore, the present invention designs a variable bending moment loading device and a bending moment calculation method for the buckling test of the trailing edge of a wind turbine blade, and selects the dangerous part of the entire blade. Through precise torque control, the cross-sectional section of the wind turbine blade is buckled and failed at a predetermined position, and its ultimate bearing capacity and failure characteristics are collected to further infer its failure mechanism. For the design of wind turbine blades, the use of the loading device and the bending moment calculation method proposed in the present invention can accurately set the failure position of the cross-section segment and control the failure mode of the cross-section segment. The test results can provide a reference basis for the structural design of the blades. Summary of the invention

[0003] In view of the deficiencies of existing testing equipment and technology for the buckling test of the trailing edge of wind turbine blades, the present invention proposes a variable bending moment loading device and a bending moment calculation method for the buckling test of the trailing edge of wind turbine blades, which can effectively calculate the bending moment exerted on the cross-section segment, and through precise torque control, the cross-section segment of the wind turbine blade can be made to buckle and fail at a predetermined position, so as to obtain its ultimate bearing capacity and failure characteristics, thereby analyzing the anti-buckling performance of the cross-section segment of the wind turbine blade.

[0004] The present invention is implemented by the following technical scheme: a variable moment loading device and a moment calculation method for the trailing edge buckling test of a wind turbine blade, wherein the loading device has a structure as follows: Figure 1 As shown, the shaft assembly structure is as follows Figure 2 shown.

[0005] The loading device consists of a cast iron platform, a steel structure tooling, a loading device, a clamping device, a loading control system and a data acquisition system. Figure 1 and Figure 2The components are described as follows: 1 is a cast iron platform; 21 is a hydraulic cylinder fixing seat; 22 is a left hydraulic cylinder; 23 is a cantilever; 24 is a right hydraulic cylinder; 3 is a rotating shaft assembly; 31 is a loading arm; 32 is a column; 33 is a column end shaft seat; 34 is a force arm end shaft seat; 35 is a copper sleeve; 36 is a rotating shaft; 41 is a wooden plywood; 42 is a wooden plywood reinforcement plate; 43 is a wind turbine blade trailing edge buckling sample: (1) The steel structure tooling is composed of a loading arm, a column and a rotating shaft, wherein the rotating shaft assembly is composed of a column end shaft seat, a force arm end shaft seat, a copper sleeve and a rotating shaft; (2) There is a loading arm on each side of the loading device, and there is a column on each side of each loading arm, and the rotating shaft assembly is distributed between the column and the loading arm; (3) The cast iron platform is the foundation of the loading device. The bottom of the column is connected to the cast iron platform by T-type bolts and nuts. The cast iron platform is provided with a well-shaped T-slot every 200 mm. The column can be adjusted in two directions along the T-slot to adapt to different cross-sectional sizes of wind turbine blades. (4) A rotating shaft assembly is provided on both sides of the steel structure tooling, and the loading arm is located in the middle of the column. The loading arm and the column are hingedly connected through the rotating shaft assembly. The loading arm can rotate around the axis of the rotating shaft assembly to apply a bending moment force to the cross-section of the wind turbine blade; (5) The shaft seat at the column end of the rotating shaft assembly is connected to the column through bolts and the internal threaded holes of the column, and the shaft seat at the force arm end of the rotating shaft assembly is connected to the loading force arm through bolts and the internal threaded holes of the loading force arm. A round hole is provided on the lower side of the loading force arm, and the entire rotating shaft passes through the loading force arm. A copper sleeve is provided on the outer side of the rotating shaft to reduce the friction between the shaft seat at the column end and the shaft seat at the force arm end when they rotate around the rotating shaft; (6) The loading device consists of a hydraulic cylinder fixing seat, a cantilever and a hydraulic cylinder; (7) The hydraulic cylinder fixing seat is connected to the cast iron platform by T-type bolts and nuts. The hydraulic cylinder fixing seat can be adjusted in two directions along the grid of the cast iron platform to meet different loading requirements; (8) The hydraulic cylinder fixing seat is hingedly connected to the lifting lug at the bottom of the hydraulic cylinder through a pin shaft. When the hydraulic cylinder is extended or retracted, the rotation of the hydraulic cylinder around the hinge shaft can adapt it to different deformation postures of the cross-section of the wind turbine blade; (9) The lifting lug at the top of the hydraulic cylinder is hingedly connected to the cantilever through a pin shaft, and the cantilever and the loading arm are connected through bolts and nuts. When the hydraulic cylinder is extended and retracted, the loading arm can rotate around the rotating shaft under the action of the cantilever, thereby applying a bending moment force to the trailing edge of the cross-section of the wind turbine blade; (10) The loading device is equipped with two hydraulic cylinders. The hydraulic cylinders on both sides can freely adjust the opening and closing of the cantilever and the loading arm according to the test requirements, and apply different bending moments to the sample respectively; (11) The cross-section of the wind turbine blade is fixed to the steel structure tooling through a clamping device, and the clamping device is composed of a wooden plywood and a wooden plywood fixing plate; (12) Plywood is a combination of multiple layers of wood boards with a thickness of 10 to 100 mm and a total thickness of 100 to 500 mm, or a one-piece wooden block made from a single layer of solid wood core with a thickness of 100 to 500 mm; (13) The wooden plywood is located between the wooden plywood fixing plate and the loading force arm. The three are connected and clamped by bolts and nuts. The wooden plywood fixing plate is used to improve the stress performance of the wooden plywood. (14) The wooden plywood and the cross-section of the wind turbine blade are in contact connection, and the position between the two is not absolutely fixed. The wooden plywood only limits the relative position of the cross-section of the wind turbine blade in the length direction; (15) The data acquisition system collects the bending moment, deformation and material strain of the cross-section of the wind turbine blade to analyze the buckling performance of the trailing edge of the wind turbine blade; (16) The loading control system controls the telescopic cylinder of the hydraulic cylinder through the hydraulic servo system, and uses the signal of the data acquisition system as feedback to form a closed loop to achieve precise control of bending moment and deformation.

[0006] right Figure 3 The components are described as follows: 5 is the blade torsion center; (1) The calculation method of bending moment is based on the position of the torsion center of the wind turbine blade section, the thrust of the hydraulic cylinders on both sides, the arm size and the cantilever size: (2) First, select the position of the torsion center of the wind turbine blade cross section and determine the lengths L1 and L2 of the torsion arm; (3) The product of the torque arm and the hydraulic cylinder thrust S The torsional force on both sides of the cross-section of the wind turbine blade is expressed as follows: (1) (4) According to formula (1), the proportional relationship of the thrust of the hydraulic cylinders on both sides is determined as follows: (2) (5) At the same time, by controlling the ratio of the loading force F on both sides a , the size ratio of the torsion arm can be controlled, and then the position of the torsion center can be controlled, see formula (3): (3) (6) When the control system accurately controls the thrust F of the hydraulic cylinder, the cross-section of the wind turbine blade can buckle and fail at a predetermined position. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The overall structure diagram of the loading device Figure 2 This is a schematic diagram of the overall structure of the shaft assembly. Figure 3 Schematic diagram of the parameters and methods used for bending moment calculation Figure 4 It is a specific implementation flow chart Figure 5 It is the control logic diagram of the control system DETAILED DESCRIPTION

[0008] A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test, wherein the loading method comprises the following steps: (1) Adjust the position of the column and hydraulic cylinder fixing seat according to the cross-sectional size of the wind turbine blade in the trailing edge buckling test; (2) Arrange the control system. The hydraulic cylinders on both sides are kept in position under the control of the control system, so that the loading arm remains in a vertical position and is stationary, so as to facilitate the installation of the sample; (3) The cross-section of the wind turbine blade is fixed to the wooden plywood by hoisting. At this time, the wooden plywood is in a raised state relative to the cross-section, rather than a relatively fixed state; (4) The wind turbine blade section and the wooden plywood assembly are hoisted and installed between the loading arms, and are fixed with bolts and nuts; (5) Determine the bending moment of the cross-section before the test, determine the force and ratio of the hydraulic cylinders on both sides according to the bending moment calculation method, and then arrange the signal acquisition system; (6) Under the control of the control system, the corresponding hydraulic cylinders are driven to apply variable bending moments to both sides of the sample, which eventually causes the cross-section to buckle and fail at a predetermined position in the trailing edge area. The data acquisition system records the bending moment, deformation, and surface strain data of the sample, thereby analyzing the anti-buckling performance of the wind turbine blade cross-section.

Claims

1. A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test, characterized in that: The loading device consists of a cast iron platform, a steel structure tooling, a loading device, a clamping device, a loading control system and a data acquisition system. The cast iron platform is the basis of the loading device. A rotating shaft assembly is set on both sides of the steel structure tooling. The cross-section of the wind turbine blade is fixed to the steel structure tooling through a clamping device. Under the action of the control system, the loading devices on both sides provide variable bending moments for the steel structure tooling and transmit them to the cross-section of the wind turbine blade, causing the trailing edge of the cross-section to buckle and fail until the structure collapses. The data acquisition system collects various data to analyze the blade performance after the test.

2. A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test according to claim 1, characterized in that: The steel structure tooling is composed of a loading arm, a column and a rotating shaft. The rotating shaft assembly is composed of a column end shaft seat, a force arm end shaft seat, a copper sleeve and a rotating shaft. (1) There is a loading arm on each side of the loading device, and there is a column on each side of each loading arm, and the rotating shaft assembly is distributed between the column and the loading arm; (2) The bottom of the column is connected to the cast iron platform by T-type bolts and nuts. The cast iron platform is provided with a well-shaped T-slot every 200 mm. The column can be adjusted in two directions along the T-slot to adapt to different cross-sectional sizes of wind turbine blades; (3) The loading arm is located in the middle of the column. The loading arm and the column are hingedly connected by a rotating shaft assembly. The loading arm can rotate around the axis of the rotating shaft assembly to apply a bending moment force to the cross-section of the wind turbine blade; (4) The shaft seat at the column end of the rotating shaft assembly is connected to the column through bolts and the internal threaded holes of the column. The shaft seat at the force arm end of the rotating shaft assembly is connected to the loading force arm through bolts and the internal threaded holes of the loading force arm. A round hole is provided on the lower side of the loading force arm. The entire rotating shaft passes through the loading force arm. A copper sleeve is provided on the outer side of the rotating shaft to reduce the friction between the shaft seat at the column end and the shaft seat at the force arm end when they rotate around the rotating shaft.

3. A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test as described in claims 1-2, characterized in that: The loading device consists of a hydraulic cylinder fixing seat, a cantilever and a hydraulic cylinder. (1) The hydraulic cylinder fixing seat is connected to the cast iron platform by T-type bolts and nuts. The hydraulic cylinder fixing seat can be adjusted in two directions along the grid of the cast iron platform to meet different loading requirements; (2) The hydraulic cylinder fixing seat and the lifting lug at the bottom of the hydraulic cylinder are hingedly connected by a pin shaft. When the hydraulic cylinder is extended or retracted, the rotation of the hydraulic cylinder around the hinge axis can adapt it to different deformation postures of the cross-section of the wind turbine blade; (3) The lifting lug at the top of the hydraulic cylinder is hingedly connected to the cantilever through a pin shaft, and the cantilever and the loading arm are connected through bolts and nuts. When the hydraulic cylinder is extended or retracted, the loading arm can rotate around the rotating shaft under the action of the cantilever, thereby applying a bending moment force to the trailing edge of the cross-section of the wind turbine blade; (4) The loading device is equipped with two hydraulic cylinders. The hydraulic cylinders on both sides can freely adjust the opening and closing of the cantilever and the loading arm according to the test requirements, and apply different bending moments to the sample.

4. A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test as described in claims 1-3, characterized in that: The clamping device consists of a wooden plywood and a wooden plywood fixing plate. (1) Plywood is a combination of multiple layers of wood boards with a thickness of 10 to 100 mm and a total thickness of 100 to 500 mm, or a one-piece wooden block made from a single layer of solid wood core with a thickness of 100 to 500 mm; (2) The wooden plywood is located between the wooden plywood fixing plate and the loading force arm. The three are connected and clamped by bolts and nuts. The wooden plywood fixing plate is used to improve the stress performance of the wooden plywood; (3) The wooden plywood and the cross-section of the wind turbine blade are in contact connection, and the position between the two is not absolutely fixed. The wooden plywood only limits the relative position of the cross-section of the wind turbine blade in the length direction.

5. A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test according to claim 1, characterized in that: The data acquisition system collects the bending moment, deformation and material strain of the cross-section of the wind turbine blade to analyze the buckling performance of the trailing edge of the wind turbine blade. The loading control system controls the telescopic cylinder of the hydraulic cylinder through the hydraulic servo system, and uses the signal of the data acquisition system as feedback to form a closed loop to achieve precise control of bending moment and deformation.

6. A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test as claimed in claims 1 to 5, characterized in that: (1) The calculation method of bending moment is based on the position of the torsion center of the wind turbine blade cross section, the thrust of the hydraulic cylinders on both sides, the arm size and the cantilever size; (2) First, select the position of the torsion center of the wind turbine blade cross section and determine the lengths of the torsion arm L1 and L 2; (3) The product of the torque arm and the hydraulic cylinder thrust S The torsional force on both sides of the cross-section of the wind turbine blade is expressed as follows: （1） (4) According to formula (1), the proportional relationship of the thrust of the hydraulic cylinders on both sides is determined as follows: （2） (5) At the same time, by controlling the ratio of the loading force F on both sides a , the size ratio of the torsion arm can be controlled, and then the position of the torsion center can be controlled, see formula (3): （3） (6) When the control system accurately controls the thrust F of the hydraulic cylinder, the cross-section of the wind turbine blade can buckle and fail at a predetermined position.

7. A variable moment loading device and moment calculation method for a wind turbine blade trailing edge buckling test as claimed in claims 1 to 6, wherein the loading method comprises the following steps: (1) Adjust the position of the column and hydraulic cylinder fixing seat according to the cross-sectional size of the wind turbine blade in the trailing edge buckling test; (2) Arrange the control system. The hydraulic cylinders on both sides are kept in position under the control of the control system, so that the loading arm remains in a vertical position and is stationary, so as to facilitate the installation of the sample; (3) The cross-section of the wind turbine blade is fixed to the wooden plywood by hoisting. At this time, the wooden plywood is in a raised state relative to the cross-section, rather than a relatively fixed state; (4) The wind turbine blade section and the wooden plywood assembly are hoisted and installed between the loading arms, and are fixed with bolts and nuts; (5) Determine the bending moment of the cross-section before the test, determine the force and ratio of the hydraulic cylinders on both sides according to the bending moment calculation method, and then arrange the signal acquisition system; (6) Under the control of the control system, the corresponding hydraulic cylinders are driven to apply variable bending moments to both sides of the sample, which eventually causes the cross-section to buckle and fail at a predetermined position in the trailing edge area. The data acquisition system records the bending moment, deformation, and surface strain data of the sample, thereby analyzing the anti-buckling performance of the wind turbine blade cross-section.

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