A method of flexible wing stiffness measurement

Abstract

The present application belongs to the technical field of flexible body aircraft, and specifically discloses a flexible wing rigidity measuring method, which is realized based on a flexible wing static strength and rigidity measuring platform, and comprises a test bench support frame, a test piece fixing table, a support rod, a pull rope, a range finder and a counterweight loading piece. The rigidity measuring method comprises: test working condition load calculation; flexible wing test piece installation; flexible wing test piece marking; counterweight loading piece design and preparation; test working condition equivalent loading; bending and torsional rigidity boundary measurement; and measurement result post-processing. The measuring method significantly improves the loading precision, can simulate the load under the bending, torsion or bending and torsion combined conditions of the flexible wing, and obtains the rigidity and instability boundary. The measuring method solves the defects of the traditional flexible wing structure rigidity measuring method, which can only roughly load and cannot be overloaded, and can measure the carrying capacity and rigidity of the flexible wing with large aspect ratio and large carrying capacity for special purposes.

Description

Technical Field

[0001] This invention belongs to the field of flexible body aircraft technology, specifically relating to a method for measuring the stiffness of a flexible wing. Background Technology

[0002] Flexible wing aircraft possess significant application value due to their lightweight and retractable characteristics, especially suitable for aircraft with strict space requirements. Compared to traditional rigid wings, flexible wings suffer from lower wing stiffness and uncertain performance, necessitating measurements of their stiffness and static strength.

[0003] While static strength testing methods for rigid wings are well-established, their application to stiffness measurement in flexible wings presents significant challenges, including the inability to accurately apply aerodynamic load distribution, improper loading procedures, and incompatible fixtures. Consequently, they cannot be directly used for performance testing of real flexible wing products. However, to meet the requirements of flight environments, accurate measurement of stiffness and static strength is crucial for the performance finalization of lightweight flexible wing products.

[0004] Therefore, it is necessary to study a precise measurement method for the stiffness and static strength of flexible wings to simulate real load conditions. The measurement accuracy, reliability, and other aspects of this method must meet the testing requirements. Summary of the Invention

[0005] In view of this, the present invention provides a method for measuring the stiffness of a flexible airfoil. This method has high loading accuracy, can standardize and refine the stiffness measurement of the flexible airfoil, and can simulate the load under bending, torsion or combined bending and torsion conditions of the flexible airfoil to obtain the stiffness and instability boundary.

[0006] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0007] In a first aspect, the present invention provides a method for measuring the stiffness of a flexible wing. This method is based on a static strength and stiffness measurement platform for a flexible wing. The platform includes a test bench support frame, a specimen fixing platform, a support rod, a rope, a rangefinder, and a counterweight loading component. The test bench support frame is fixedly installed on the ground. The specimen fixing platform is fixedly installed on the top of the test bench support frame and is used to securely clamp the wing root of the flexible wing specimen, leaving one end of the wingtip suspended. The support rod is vertically positioned, with its bottom end fixedly connected to the top of the test bench support frame. The flexible wing specimen is stiffened using the support rod and the rope. The rangefinder is used to measure the distance between a marked point on the flexible wing specimen and the ground. The counterweight loading component is used to load the flexible wing specimen. The stiffness measurement method includes the following steps: The first step is to calculate the load under test conditions. Step 2: Installation of the flexible wing test component; Third step: Marking the flexible wing test piece; Step 4: Design and fabrication of counterweight loading components; Step 5: Test the equivalent loading of the working conditions; Step 6: Bending and torsional stiffness boundary measurement; The seventh step is post-processing of the measurement results.

[0008] Furthermore, the first step specifically includes: according to the atmospheric environment in which the flexible wing aircraft actually flies, using computational fluid dynamics methods to obtain aerodynamic external load distribution data of the flexible wing under typical operating conditions; dividing the flexible wing into several regions along its span direction, extracting the external pressure distribution of the flexible wing in each region, calculating the equivalent load center position of the external load in the normal direction of the flexible wing surface, and then calculating the equivalent resultant force of each region.

[0009] Furthermore, the second step specifically includes: clamping the wing root of the flexible wing test piece to the test piece fixing platform, suspending one end of the wingtip in the air, attaching a pull rope to the middle and wingtip of the flexible wing test piece, connecting the other end of the pull rope to the top of the support rod, applying a pre-tension force to the pull rope, and connecting the air inlet of the flexible wing test piece to an external inflation device.

[0010] Furthermore, the third step specifically includes: dividing the flexible wing test piece into several regions along its span according to the method of measuring stiffness or static strength, using a three-dimensional scanning level to assist in drawing lines, and marking the lines with a marker pen; the counterweight loading position of each region should avoid the tethering position of the rope and the flexible wing test piece, and marking the points for measurement with a marker pen.

[0011] Furthermore, the fourth step specifically includes: Based on the calculation results of equivalent aerodynamic loads in different regions, the number, placement, and step-by-step loading strategies of counterweight loaders in each loading region along the span of the flexible wing test piece are determined. The counterweight loading components are cylindrical counterweight bags, and the bags are made using a sewing process. Each bag is numbered according to the weight of the counterweight loading components in each area, based on the loading area and loading position.

[0012] Furthermore, the fifth step specifically includes: following the design principle of progressive loading, gradually applying stiffness and static strength tests to each loading area of ​​the flexible wing test piece; using the aforementioned counterweight loading components (iron sandbags or quartz sandbags) on the flexible wing test piece, uniformly applying multi-point loading along the chord direction of the flexible wing test piece; the loading method is the same under different aerodynamic external load conditions; the segment positions of each loading area, the magnitude of the loading load, and the size of the counterweight loading bag under different conditions are all based on the test loading design for each condition; the equivalent loading principle of the test conditions follows that the aerodynamic resultant force, resultant moment, loading position of each loading area of ​​the flexible wing test piece are consistent with the center position of the aerodynamic external load of each area.

[0013] Furthermore, the sixth step specifically includes: based on the equivalent loading strategy formulated according to the external load distribution of the test conditions, measuring the static strength and stiffness of the flexible wing test piece under bending and torsional conditions. During the measurement, the distance from the ground to the marked point of the flexible wing test piece is measured sequentially according to three states: before loading, after loading, and after unloading.

[0014] Furthermore, the seventh step specifically includes: recording the total weight of the counterweight loading components, the tension of the rope, and the change in ground clearance of the flexible wing test piece at different marked points from the wing root to the wingtip under different working conditions; and calculating the equivalent stiffness, static strength, and maximum instability boundary of the flexible wing test piece.

[0015] Secondly, the present invention also provides a static strength and stiffness measurement platform for flexible wings, which is used in the above-mentioned method for measuring the stiffness of flexible wings, and includes a test bench support frame, a specimen fixing table, a support rod, a pull rope, a rangefinder, and a counterweight loading component. The test bench support frame is fixed to the ground; the specimen fixing platform is fixedly installed on the top of the test bench support frame and is used to fix and clamp the wing root of the flexible wing test specimen, so that one end of the wingtip of the flexible wing test specimen is suspended in the air; the support rod is set vertically and its bottom end is fixedly installed on the top of the test bench support frame; the flexible wing test specimen is reinforced with the support rod and the pull rope; the counterweight loading component is used to load the flexible wing test specimen; the rangefinder is used to measure the distance between the marked point of the flexible wing test specimen and the ground.

[0016] Furthermore, the test bench support frame is a truss structure, and its bottom is fixed to the ground by a clamping lock; Multiple pull ropes are attached between the support rod and the flexible wing test piece; one end of each pull rope is attached to the top of the support rod, and the other end is attached to the upper surface of the flexible wing test piece. The specimen fixing platform is a tooling fixture that is fixed to the test platform support frame by bolts; the tooling fixture has a hollow structure, with an installation interface for installing flexible wing test specimens on one end face, and a spaced through groove communicating with the installation interface on the top surface.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. The flexible wing stiffness measurement method of the present invention is highly targeted at testing the stiffness and static strength of highly flexible lightweight wing structures with strut and cable stiffness reinforcement. It establishes a complete flexible wing stiffness testing procedure, standardizes and refines the measurement of flexible wing stiffness, and has universality in the field of flexible wing stiffness and static strength testing. At the same time, the flexible wing static strength and stiffness measurement platform used in this flexible wing stiffness measurement method can also meet the testing requirements of rigid wing stiffness.

[0018] 2. The flexible wing stiffness measurement method of the present invention uses a flexible wing static strength and stiffness measurement platform, which solves the defects of traditional flexible structure stiffness measurement methods that can only be roughly loaded and cannot be heavily loaded. It can measure the load-bearing capacity and stiffness of large aspect ratio, high load-bearing special purpose flexible wings, and can also measure the instability boundary of flexible wings.

[0019] 3. The flexible wing stiffness measurement method of the present invention is designed with a special counterweight loading component. The weight of the counterweight loading component in each area can be customized, and the accuracy can reach 0.1g. Compared with the traditional loading method, the loading accuracy is significantly improved. By flexibly loading the counterweight loading component in position and arrangement, the load under bending, torsion or bending-torsion combination conditions of the flexible wing can be simulated to obtain the stiffness and instability boundary.

[0020] 4. The flexible wing stiffness measurement method in this invention adopts a wing partition loading method and a step-by-step loading strategy. The equivalent loading principle follows that the aerodynamic resultant force, resultant moment, loading position and the center position of the aerodynamic external load in each loading area of ​​the wing are consistent. The aerodynamic load simulation accuracy of the flexible wing under typical working conditions is higher and more scientific than the traditional method.

[0021] Based on the above reasons, the flexible wing stiffness measurement method of the present invention can be widely promoted in the field of flexible body aircraft technology. Attached Figure Description

[0022] Figure 1 A flowchart illustrating the method for measuring the stiffness of a flexible airfoil; Figure 2 This is an overall layout diagram of the static strength and stiffness measurement platform used in the flexible wing stiffness measurement method of the present invention; Figure 3 This is a schematic diagram showing the division of the aerodynamic load loading area for a flexible airfoil. Figure 4This is a schematic diagram of the actual equivalent loading for the stiffness test of the flexible wing structure.

[0023] Figure label: 1-Support rod, 2-Pull rope, 3-Specimen fixing platform, 4-Test platform support frame, 5-Flexible wing test specimen, 6-Distance measuring device, 11-Counterweight loading component. Detailed Implementation

[0024] 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 only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0026] Example 1 This embodiment provides a platform for measuring the static strength and stiffness of a flexible airfoil, such as... Figure 2 , Figure 3 and Figure 4 As shown, the flexible wing static strength and stiffness measurement platform is used in the flexible wing stiffness measurement method, and includes a support rod 1, a tension rope 2, a specimen fixing platform 3, a test platform support frame 4, a rangefinder 6, and a counterweight loading component 11; wherein: The test bench support frame 4 is a truss structure, with its bottom placed on the ground and fixed to the ground by clamping and locking devices. The specimen fixing table 3 is fixedly installed on the top of the test bench support frame 4 and is used to fix and clamp the wing root of the flexible wing test specimen 5, so that one end of the wingtip of the flexible wing test specimen 5 is suspended in the air. The specimen fixing table 3 is a tooling fixture, which is fixed to the test bench support frame 4 by bolts; the tooling fixture has a hollow structure, with an installation interface for installing the flexible wing test specimen 5 on one end face, and a spaced through groove communicating with the installation interface on the top surface. The cross-sectional shape of the mounting interface is the same as the airfoil shape of the flexible wing test piece 5 after inflation and pressurization, so that the flexible wing test piece 5 can be installed in the mounting interface in a shape-fitting manner, and the flexible wing test piece 5 can pass through the mounting interface without obstruction. The upper surface of the specimen fixing table 3 is provided with a spacer groove. When the flexible wing test piece 5 is clamped by a tooling fixture, the inflation nozzle of the flexible wing test piece 5 can pass through the spacer groove, and the inflation nozzle is connected to the inflation device through the air pipe, and the flexible wing test piece 5 is inflated by the inflation device.

[0027] Support rod 1 is installed vertically, and its bottom end is fixed to the top of test bench support frame 4 by bolts; the flexible wing test piece 5 is reinforced with support rod 1 and tension rope 2; such as Figure 2 and Figure 4 As shown, four pull ropes 2 are tied between the support rod 1 and the flexible wing test piece 5. One end of the pull rope 2 is tied to the top of the support rod 1, and the other end is tied to the middle of the upper surface of the flexible wing test piece 5 or the wingtip (the outer end of the flexible wing test piece 5, i.e. the end of the flexible wing test piece 5 away from the test piece fixing platform 3). The pull ropes 2 are pre-tightened according to the actual test requirements.

[0028] The counterweight loading component 11 is used to load the flexible wing test piece 5; the rangefinder 6 is used to measure the distance between the marked points of the flexible wing test piece 5 and the ground. The rangefinder 6 is placed on the ground, and a one-to-one corresponding rangefinder 6 can be set according to the marked points of the flexible wing test piece 5. The counterweight loading component 11 can be a cylindrical counterweight bag filled with iron sand or quartz sand. The bag body is made of non-slip fiber fabric sprayed with an adhesive layer and is formed by sewing. According to the designed weight of the counterweight loading component 11 in each area, the bag body of each counterweight loading component 11 is filled with iron sand or quartz sand, and the counterweight accuracy can reach 0.1g. After completion, the bag opening is sealed by sewing.

[0029] Flexible wings can be configured with multiple airbags or a dot matrix structure, and their load-bearing capacity and stiffness can be measured for special-purpose flexible wings with high aspect ratio and high load capacity.

[0030] Example 2 like Figure 1As shown, this embodiment provides a method for measuring the stiffness of a flexible wing. This stiffness measurement method is based on the aforementioned flexible wing static strength and stiffness measurement platform and includes the following steps: The first step is to calculate the load under test conditions: Based on the atmospheric environment of the actual flight of the flexible wing aircraft, the aerodynamic external load distribution data of the flexible wing under typical operating conditions is obtained using computational fluid dynamics methods; the flexible wing is divided into several regions along the span direction, the external pressure distribution of the flexible wing in each region is extracted, and the equivalent load center position of the external load in the normal direction of the flexible wing surface is calculated, and then the equivalent resultant force of each region is calculated.

[0031] Second step: Installation of flexible wing test piece 5: The wing root of the flexible wing test piece 5 is clamped to the test piece fixing platform 3, and one end of the wingtip is suspended in the air. The middle and wingtip of the flexible wing test piece 5 are tied with a pull rope 2. The other end of the pull rope 2 is connected to the top of the support rod 1. A pre-tightening force is applied to the pull rope 2, and the air inlet of the flexible wing test piece 5 is connected to an external air inflation device.

[0032] Third step: Marking the flexible wing test piece 5: Divide the flexible wing test piece 5 into several areas along its span according to the method of measuring stiffness or static strength. Use a three-dimensional scanning level to draw lines and mark the lines with a marker. The counterweight loading position of each area should avoid the tethering position of the rope 2 and the flexible wing test piece 5. Mark the marking points for measurement with a marker.

[0033] Step 4: Design and fabrication of counterweight loading components 11: Based on the calculation results of equivalent aerodynamic loads in different regions, determine the quantity, placement, and step-by-step loading strategy of counterweight loading components 11 for each loading region along the span of the flexible wing test piece 5; the counterweight loading components 11 are cylindrical counterweight bags, and the bags are made using sewing technology. Based on the designed weight of the counterweight loading components 11 in each region, each bag is numbered according to the loading region and loading position.

[0034] Step 5: Equivalent Loading under Test Conditions: Following the design principle of progressive loading, stiffness and static strength tests are gradually applied to each loading area of ​​the flexible wing test piece 5. The aforementioned counterweight loading component 11 (iron sandbag or quartz sandbag) is used on the flexible wing test piece 5, and multi-point loading is uniformly applied along the chord direction of the flexible wing test piece 5. The loading method is the same under different aerodynamic external load conditions. The segment positions, loading load magnitudes, and counterweight loading bag dimensions of each loading area under different conditions are all based on the test loading design for each condition. The equivalent loading principle of test conditions follows that the aerodynamic resultant force, resultant moment, loading position, and aerodynamic external load center position of each loading area of ​​the flexible wing test piece 5 are consistent with the aerodynamic external load center position of each area.

[0035] Step 6: Bending and Torsional Stiffness Boundary Measurement: Based on the equivalent loading strategy formulated according to the external load distribution of the test conditions, the static strength and stiffness of the flexible wing test piece 5 under bending and torsional conditions are measured. During the measurement, the distance from the ground to the marked point of the flexible wing test piece 5 is measured sequentially according to the three states before loading, after loading, and after unloading.

[0036] Step 7: Post-processing of measurement results: Record the total weight of the counterweight loading component 11, the tension of the rope 2, and the change in ground clearance of the flexible wing test component 5 from the wing root to the wingtip of different marked points under different working conditions. Calculate the equivalent stiffness, static strength, and maximum instability boundary of the flexible wing test component 5.

[0037] Example 3 This embodiment provides a method for measuring the stiffness of a flexible airfoil, the specific steps of which are as follows: The first step is to calculate the load under test conditions: Based on the atmospheric environment of the actual flight of the flexible wing aircraft and the requirements for calculating the ballistic load, the aerodynamic external load distribution data of the flexible wing under typical conditions is obtained using computational fluid dynamics methods; according to the test accuracy requirements, the flexible wing test piece 5 is divided into several regions along the span direction, the external pressure distribution of the flexible wing test piece 5 in each region is extracted, and the equivalent load center position of the external load in the normal direction of the flexible wing surface is calculated, and then the equivalent resultant force of each region is calculated.

[0038] The second step is the installation of the flexible wing test piece 5: The flexible wing test piece 5 is installed on the flexible wing static strength and stiffness measurement platform. The support rod 1 is placed vertically and fixed to the test platform support frame 4 with bolts. One end of the flexible wing test piece 5 is clamped by a tooling fixture. The clamping distance of the flexible wing test piece 5 is generally 200mm~500mm. The tooling fixture is fixed to the test platform support frame 4 with bolts. The flexible wing test piece 5 passes through the tooling fixture. When clamped, the inflation nozzle and air pipe of the flexible wing test piece 5 can extend through the spacer slot to connect to an external inflation device, so as not to be squeezed or bound by the tooling fixture, ensuring the airtightness of the flexible wing test piece 5 and the safety of inflation and pressure holding during the test. The test bench support frame 4 is a truss structure. The bottom of the test bench support frame 4 is placed on the ground and fixed to the ground by clamping and locking devices. One end of the wingtip of the flexible wing test piece 5 is suspended in the air. Its end and middle are connected to the top of the support rod 1 by a pull rope 2, and a pre-tension force is applied to the pull rope 2.

[0039] The third step, marking the flexible wing test piece 5: After the flexible wing test piece 5 is installed, the marking work for the loading position, partitions, etc., is carried out before the stiffness or static strength test of the flexible wing. First, the flexible wing test piece 5 is divided into several areas along its span according to the stiffness or static strength measurement method. A three-dimensional scanning level is used to assist in drawing lines, and the lines are marked with a marker. The counterweight loading position of each area needs special attention. The tethering position between the tension rope 2 and the flexible wing test piece 5 needs to be marked with a marker for measurement and special marking points.

[0040] The fourth step, design and fabrication of the counterweight loading component 11: After the installation and marking of the flexible wing test piece 5, the design and fabrication of the counterweight loading component 11 are carried out. Based on the equivalent aerodynamic load calculation results for different regions, the number, placement, and step-by-step loading strategy of the counterweight loading components 11 for each loading region divided in the spanwise direction of the flexible wing test piece 5 are determined. To simulate the load conditions under typical working conditions of the flexible wing aircraft to the greatest extent, a dedicated counterweight loading component 11 is designed. The counterweight loading component 11 is a cylindrical counterweight bag filled with iron sand or quartz sand. The bag body is made of a non-slip fiber fabric with a sprayed adhesive layer and is formed by sewing. According to the designed weight of the counterweight loading component 11 for each region, the bag body of each counterweight loading component 11 is filled with iron sand or quartz sand and weighed (accuracy 0.1g). After completion, the bag mouth is sealed by sewing, and each bag body is numbered according to the loading region and loading position.

[0041] The fifth step is equivalent loading under test conditions: following the design principle of progressive loading, stiffness and static strength tests are gradually applied to each loading area of ​​the flexible wing test piece 5. For each segment of the flexible wing test piece 5, the aforementioned long strip-shaped counterweight loading component 11 (iron sandbag or quartz sandbag) is used, uniformly loading multiple points along the chord direction of the flexible wing test piece 5. The loading method is the same under different aerodynamic external load conditions. The segment positions, load magnitudes, and counterweight loading bag dimensions of each loading area under different conditions are all based on the test loading design for each condition. The equivalent loading principle for test conditions follows that the aerodynamic resultant force, resultant moment, loading position, and center position of the aerodynamic external load in each loading area of ​​the wing are consistent with the center position of each area.

[0042] The sixth step is to measure the bending and torsional stiffness boundaries: Based on the equivalent loading strategy formulated according to the external load distribution of the test conditions, the static strength and stiffness of the flexible wing test piece 5 under bending and torsional conditions are measured. During the measurement, the distance from the ground to the marked point of the flexible wing test piece 5 is measured sequentially according to the three states before loading, after loading, and after unloading.

[0043] Under typical aerodynamic loads, the flexible wing of an aircraft more closely resembles a complex combination of bending and torsion. Therefore, after equivalent loading with counterweight 11, the flexible wing test piece 5 will exhibit a combination of bending and torsion. The step-by-step loading strategy of the flexible wing stiffness measurement method of this invention can effectively measure the stiffness, strength, and deformation of the flexible wing test piece 5 under typical operating conditions. Furthermore, it can measure the load-bearing capacity limit and instability boundary of the flexible wing test piece 5 through continuous, step-by-step loading beyond the design load.

[0044] In addition to typical operating conditions, by employing a step-by-step loading strategy, and by adjusting the collinearity of the counterweight loading members 11 along the wing span direction in each region, while ensuring that the number and weight of the counterweight test pieces are consistent along the chord direction, the stiffness, static strength, and instability boundary of the flexible wing test piece 5 under near-pure bending conditions can be measured. Using a similar loading method, by adjusting only the spacing of the counterweight loading members 11 along the chord direction in each region along the span direction of the flexible wing test piece 5, and gradually increasing or decreasing this spacing from the wing root to the wingtip, the load-bearing simulation of the flexible wing test piece 5 under torsional conditions can be achieved, and the stiffness, static strength, and instability boundary under torsional conditions can be obtained.

[0045] The seventh step is post-processing of the measurement results: Using the above methods for measuring the stiffness, static strength, and instability boundary of the flexible wing, record the change in ground clearance of the flexible wing test piece 5 from the root to the wingtip of different marked points under different working conditions, record the total weight of the counterweight loading component 11, the tension of the rope 2, etc., and then obtain the equivalent stiffness, static strength (load capacity), and maximum instability boundary of the flexible wing test piece 5 through the corresponding calculation formulas, providing an important basis for the design optimization of the flexible wing.

[0046] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

[0047] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring the stiffness of a flexible airfoil, characterized in that, This stiffness measurement method is based on a flexible wing static strength and stiffness measurement platform. This platform includes a test bench support frame, a specimen fixing platform, a support rod, a tension rope, a rangefinder, and a counterweight loading component. The test bench support frame is fixedly installed on the ground. The specimen fixing platform is fixedly installed on the top of the test bench support frame and is used to securely hold the wing root of the flexible wing specimen, leaving the wingtip suspended. The support rod is vertically positioned, with its bottom end fixedly connected to the top of the test bench support frame. The flexible wing specimen is stiffened using the support rod and the tension rope. The rangefinder is used to measure the distance between a marked point on the flexible wing specimen and the ground. The counterweight loading component is used to load the flexible wing specimen. This stiffness measurement method includes the following steps: The first step is to calculate the load under test conditions, which includes: obtaining the aerodynamic external load distribution data of the flexible wing under typical operating conditions using computational fluid dynamics methods according to the atmospheric environment of the actual flight of the flexible wing aircraft; dividing the flexible wing into several regions along the span direction, extracting the external pressure distribution of the flexible wing in each region, calculating the equivalent load center position of the external load in the normal direction of the flexible wing surface, and then calculating the equivalent resultant force in each region. The second step: installation of the flexible wing test piece, specifically including: clamping the wing root of the flexible wing test piece to the test piece fixing platform, suspending one end of the wingtip in the air, leaving a pull rope in the middle and wingtip of the flexible wing test piece, connecting the other end of the pull rope to the top of the support rod, applying a pre-tightening force to the pull rope, and connecting the air inlet of the flexible wing test piece to an external inflation device. Third step: Marking the flexible wing test piece; Step 4: Design and fabrication of counterweight loading components; Step 5: Test the equivalent loading of the working conditions; Step 6: Bending and torsional stiffness boundary measurement; Step 7: Post-processing of measurement results.

2. The method for measuring the stiffness of a flexible wing as described in claim 1, characterized in that, The third step specifically includes: dividing the flexible wing test piece into several regions along its span according to the method of measuring stiffness or static strength, using a three-dimensional scanning level to assist in drawing lines, and marking the lines with a marker pen; the counterweight loading position of each region should avoid the tethering position of the rope and the flexible wing test piece, and marking the points for measurement with a marker pen.

3. The method for measuring the stiffness of a flexible wing as described in claim 2, characterized in that, The fourth step specifically includes: Based on the calculation results of equivalent aerodynamic loads in different regions, the number, placement, and step-by-step loading strategies of counterweight loaders in each loading region along the span of the flexible wing test piece are determined. The counterweight loading components are cylindrical counterweight bags, and the bags are made using a sewing process. Each bag is numbered according to the weight of the counterweight loading components in each area, based on the loading area and loading position.

4. The method for measuring the stiffness of a flexible wing as described in claim 3, characterized in that, The fifth step specifically includes: following the design principle of progressive loading, gradually applying stiffness and static strength tests to each loading area of ​​the flexible wing test piece; using the aforementioned counterweight loading device on the flexible wing test piece, uniformly applying multi-point loading along the chord direction of the flexible wing test piece; using the aforementioned multi-point loading method of the counterweight loading device under different aerodynamic external load conditions; the segment positions of each loading area, the magnitude of the loading load, and the size of the counterweight loading bag under different conditions are all based on the test loading design for each condition; the equivalent loading principle of the test conditions follows that the aerodynamic resultant force, resultant moment, loading position of each loading area of ​​the flexible wing test piece are consistent with the aerodynamic external load center position of each area.

5. The method for measuring the stiffness of a flexible wing as described in claim 4, characterized in that, The sixth step specifically includes: based on the equivalent loading strategy formulated according to the external load distribution of the test conditions, measuring the static strength and stiffness of the flexible wing test piece under bending and torsional conditions. During the measurement, the distance from the ground to the marked point of the flexible wing test piece is measured sequentially according to the three states before loading, after loading, and after unloading.

6. The method for measuring the stiffness of a flexible wing as described in claim 5, characterized in that, The seventh step specifically includes: recording the total weight of the counterweight loading component, the tension of the rope, and the change in ground clearance of the flexible wing test component from the wing root to the wingtip at different marked positions under different working conditions; and calculating the equivalent stiffness, static strength, and maximum instability boundary of the flexible wing test component.

7. A platform for measuring the static strength and stiffness of a flexible airfoil, characterized in that, In the flexible wing stiffness measurement method according to any one of claims 1-6, the flexible wing static strength and stiffness measurement platform includes a test bench support frame, a specimen fixing table, a support rod, a pull rope, a rangefinder, and a counterweight loading component; The test bench support frame is fixed to the ground; the specimen fixing platform is fixedly installed on the top of the test bench support frame and is used to fix and clamp the wing root of the flexible wing test specimen, so that one end of the wingtip of the flexible wing test specimen is suspended in the air; the support rod is set vertically and its bottom end is fixedly installed on the top of the test bench support frame; the flexible wing test specimen is reinforced with the support rod and the pull rope; the counterweight loading component is used to load the flexible wing test specimen; the rangefinder is used to measure the distance between the marked point of the flexible wing test specimen and the ground.

8. The flexible wing static strength and stiffness measurement platform as described in claim 7, characterized in that, The test bench support frame is a truss structure, and its bottom is fixed to the ground by a clamping lock. Multiple pull ropes are attached between the support rod and the flexible wing test piece; one end of each pull rope is attached to the top of the support rod, and the other end is attached to the upper surface of the flexible wing test piece. The specimen fixing platform is a tooling fixture that is fixed to the test platform support frame by bolts; the tooling fixture has a hollow structure, with an installation interface for installing flexible wing test specimens on one end face, and a spaced through groove communicating with the installation interface on the top surface.

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