A method and test fixture for testing the bending stiffness of a vehicle door

Abstract

The application discloses a vehicle door bending rigidity test method and a test tool, and solves the technical problem that the prior art cannot apply Z-direction torque to the door lock position of a vehicle door through physical testing and cannot understand the performance of the physical object. The test method comprises the following steps: installing a vehicle door assembly on a test bench with a limiting mechanism in the mounting posture of the vehicle door assembly on a vehicle, and installing a force transmission connecting piece at the door lock of the vehicle door assembly; applying Z-direction torque to the force transmission connecting piece so that the Z-direction torque acts on the vehicle door assembly through the force transmission connecting piece; and recording the maximum displacement of a test point on the vehicle door assembly, the test point being a sheet metal weak point obtained through CAE analysis. By applying Z-direction torque to the force transmission connecting piece, the Z-direction torque acts on the vehicle door assembly through the force transmission connecting piece, so that the application of Z-direction torque to the door lock of the vehicle door assembly in physical testing can be simulated, and the results of physical testing demonstration can be obtained.

Description

Technical Field

[0001] This application belongs to the field of vehicle door bending rigidity testing technology, specifically relating to a vehicle door bending rigidity testing method and testing fixture. Background Technology

[0002] The bending stiffness of car doors is generally simulated and calculated using CAE (Computer Aided Engineering). This involves simulating the fixed hinge side and lock side of the car door, releasing the X-axis movement and Z-axis rotation of the lock position, applying a specific torque value at the lock position, and analyzing the maximum deformation of the car door sheet metal. However, since it is impossible to apply Z-axis torque at the lock position, there is no relevant physical testing method, and it is impossible to understand the actual performance of this property. Summary of the Invention

[0003] To address the aforementioned technical problems, this application provides a method and fixture for testing the bending stiffness of a car door, which solves the technical problem in the prior art that it is impossible to apply Z-axis torque at the door lock position through physical testing, thus making it impossible to understand the performance of this property of the actual object.

[0004] The technical solution adopted to achieve the purpose of this application is as follows:

[0005] A method for testing the bending stiffness of a car door includes the following steps:

[0006] The door assembly is installed on a test bench with a limiting mechanism in the same mounting position as the vehicle assembly, and the limiting mechanism limits the door assembly; a force-transmitting connector is installed at the door lock of the door assembly.

[0007] A Z-axis torque is applied to the force transmission connector so that the Z-axis torque acts on the door assembly through the force transmission connector;

[0008] The deformation of the test points on the door assembly is obtained, and the test points are the sheet metal weak points obtained by CAE analysis.

[0009] Furthermore, before obtaining the deformation at the test points on the door assembly, the door bending stiffness test method further includes:

[0010] Install dial indicators on the test bench in the same number as the number of test points. Adjust the position of the dial indicators so that the position of the dial indicator corresponds one-to-one with the position of the test point, and the front end of the dial indicator contacts the corresponding test point.

[0011] Furthermore, the sheet metal weak points identified through CAE analysis specifically include:

[0012] CAE analysis was performed on the door assembly to obtain the test results;

[0013] The sheet metal deformation points that meet the preset conditions in the CAE analysis results are taken as the sheet metal weak points.

[0014] Furthermore, applying a Z-axis torque to the force-transmitting connector specifically includes:

[0015] Connect the force-applying component to the force-transmitting connector, and rotate the force-applying end of the force-applying component to generate a Z-axis torque.

[0016] Based on the same inventive concept, this application also provides a test fixture for the above-mentioned vehicle door bending stiffness test method, comprising:

[0017] The force transmission connector includes a cantilever, a force-bearing nut, and a connecting plate for connecting the door lock of the vehicle door assembly; the cantilever is horizontally disposed on one side of the connecting plate and perpendicular to the connecting plate; the force-bearing nut is fixedly disposed on the cantilever and is used to mate with the force-applying component to apply the Z-axis torque;

[0018] The test bench includes a base, a door fixing column for mounting the door assembly, and a door support column for supporting the door assembly. The door fixing column and the door support column are arranged side by side and are both mounted on the base. The door support column is provided with a limiting mechanism for limiting the door assembly.

[0019] Furthermore, the test bench is also equipped with a mounting column for mounting a dial indicator; the mounting column, the door fixing column, and the door support column are all detachably connected to the base.

[0020] Furthermore, the limiting mechanism is a limiting groove for accommodating the bottom of the door assembly.

[0021] Furthermore, the distance between the central axis of the force-bearing nut and the connecting plate is greater than the maximum rotation radius required for the end of the force-applying member to be closer to the connecting plate.

[0022] Furthermore, the connecting plate has at least two connecting holes, and the positions of the connecting holes correspond one-to-one with the mounting holes of the door assembly.

[0023] Furthermore, the number of connecting holes is three; the connecting plate has a triangular structure, and the three connecting holes are respectively located at the three corners of the connecting plate; all three corners of the connecting plate are chamfered.

[0024] As can be seen from the above technical solution, the door bending rigidity test method provided in this application involves installing the door assembly on a test bench with a limiting mechanism in the same mounting posture as the vehicle, and limiting the door assembly by the limiting mechanism; installing a force-transmitting connector at the door lock of the door assembly; applying a Z-axis torque to the force-transmitting connector so that the Z-axis torque acts on the door assembly through the force-transmitting connector; and obtaining the deformation amount at a test point on the door assembly, where the test point is a sheet metal weak point obtained through CAE analysis. By applying a Z-axis torque to the force-transmitting connector so that the Z-axis torque acts on the door assembly through the force-transmitting connector, the application of a Z-axis torque at the door lock of the door assembly in a physical test can be simulated, obtaining the results of the physical test. By analyzing and comparing the sheet metal deformation amount obtained from the physical test with the sheet metal deformation amount obtained from the CAE analysis, the CAE analysis method can be continuously optimized, and the accuracy of the CAE analysis can be improved.

[0025] The test fixture provided in this application for the above-mentioned door bending rigidity test method simulates the application of Z-axis torque at the door lock of the door assembly by installing a force-transmitting connector at the door lock of the door assembly and applying force to the force-bearing nut through a force-applying component. Then, the door assembly is installed on the test bench to conduct the door bending rigidity test, which solves the technical problem in the prior art that it is impossible to apply Z-axis torque at the door lock position through physical testing and thus cannot understand the performance of this property of the actual object. Attached Figure Description

[0026] Figure 1 This is a flowchart of the door bending rigidity test method in Embodiment 1 of this application.

[0027] Figure 2 This is a schematic diagram of the structure of the test fixture in Embodiment 2 of this application after it is assembled with the door assembly during the door bending rigidity test, from a certain perspective.

[0028] Figure 3 This is a schematic diagram of the force transmission connector in the embodiments of this application.

[0029] Figure 4 This is a schematic diagram of the test fixture in Embodiment 2 of this application after it is assembled with the door assembly during the door bending rigidity test, viewed from another angle.

[0030] Figure 5 for Figure 4 A magnified structural diagram of point A in the middle.

[0031] Figure 6 for Figure 4 A magnified structural diagram at point B in the middle.

[0032] Figure 7This is a schematic diagram of the force-applying component used in the door bending rigidity test method in the embodiments of this application.

[0033] Figure 8 This is a front view of the force transmission connector of the test fixture in this embodiment after it is assembled with the door assembly.

[0034] Figure 9 for Figure 8 Enlarged structural diagram at point C.

[0035] Figure 10 This is a side view of the force-transmitting connector of the test fixture in this embodiment after it is assembled with the door assembly.

[0036] Figure 11 For this application Figure 10 Enlarged structural diagram at point D.

[0037] Explanation of reference numerals in the attached drawings: 1-Door assembly; 2-Test bench; 21-Door fixing column; 22-Door support column; 23-Dial indicator mounting column; 24-Dial indicator; 25-Force application component; 251-Head; 252-Handle; 26-Limiting mechanism; 3-Force transmission connector; 31-Connecting plate; 32-Cantilever; 33-Force-bearing nut; 34-Connecting hole. Detailed Implementation

[0038] To enable those skilled in the art to better understand this application, the technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] During vehicle use, passengers need to enter or exit the vehicle by opening and closing the doors. When closing the door, the stress point of the door assembly is mainly concentrated at the door lock. Therefore, after several closings, it is equivalent to applying force to the door lock several times, which will have a certain impact on the door assembly and cause the door to bend and deform. In existing technologies, CAE analysis is generally used to simulate the force acting on the door lock and obtain the deformation point of the door sheet metal. The design of the door assembly is then continuously improved based on the results of the analysis and simulation. However, the accuracy of CAE analysis methods cannot be verified by physical testing methods, which may introduce certain errors and pose certain design risks to the later product design.

[0040] To address the technical problem in existing technologies where it is impossible to apply Z-axis torque to the door lock position through physical testing, thus hindering understanding of this performance characteristic of the actual vehicle, this application provides a method and fixture for testing the bending stiffness of a vehicle door. By installing a force-transmitting connector at the door lock and applying Z-axis torque at the connector through a force-applying component, the problem of the lack of a physical testing method in existing technologies can be solved, achieving the goal of obtaining results for verification through physical testing. The content and effects of this application will be described in detail below through specific embodiments:

[0041] Example 1:

[0042] This application provides a method for testing the bending stiffness of a car door, see Appendix. Figure 1 The process includes the following steps: mounting the door assembly onto a test bench with a limiting mechanism in the same orientation as the vehicle assembly, and limiting the door assembly by the limiting mechanism; installing a force-transmitting connector at the door lock of the door assembly; applying a Z-axis torque to the force-transmitting connector so that the Z-axis torque acts on the door assembly through the force-transmitting connector; and obtaining the deformation of test points on the door assembly, wherein the test points are sheet metal weak points obtained through CAE analysis.

[0043] By installing corresponding force-transmitting connectors at the door lock of the door assembly, the Z-axis torque can be applied to the door assembly during the door bending rigidity test. This simulates the Z-axis torque applied at the door lock during the actual test, allowing for verification of the results from the actual test. By comparing the sheet metal deformation obtained from the actual test with the sheet metal deformation obtained from CAE analysis, the CAE analysis method can be continuously optimized, improving its accuracy.

[0044] In some embodiments, before obtaining the deformation of the test points on the door assembly, the door bending stiffness test method further includes: installing dial indicators on the test bench in the same number as the test points, adjusting the position of the dial indicators so that the position of the dial indicators corresponds one-to-one with the position of the test points, and the front end of the dial indicator contacts the corresponding test point. A dial indicator is a length measuring instrument that converts general linear displacement or linear motion into pointer rotational motion through gears or levers, and then takes a reading on a scale. It is mainly used to check the shape and position errors of workpieces, such as roundness, flatness, perpendicularity, and circular runout, and is also commonly used for precision alignment of workpieces.

[0045] In some embodiments, the number of dial gauges is determined based on the number of sheet metal weak points obtained from the CAE analysis. The number of dial gauges can be equal to the number of sheet metal weak points (one, two, or more), and their positions correspond one-to-one with the test points. By conducting physical experiments at the corresponding test points, the data results of the physical experiments can be compared with the CAE analysis data to analyze the differences. Subsequently, the CAE analysis method can be optimized based on these differences to improve the accuracy of the CAE analysis, thereby enhancing the accuracy of the early data design stage and reducing later analysis errors to some extent.

[0046] In some embodiments, the sheet metal weak points obtained through CAE analysis specifically include: performing CAE analysis on the door assembly to obtain test results; where CAE (Computer Aided Engineering) refers to computer-aided engineering in engineering design, which refers to using computers to help solve and analyze the structural mechanical properties of complex engineering projects and products, as well as optimize structural performance, etc., organically organizing the various aspects of the product. Its key is to integrate relevant information so that it is generated and exists throughout the product's entire life cycle. CAE software can perform static structural analysis, dynamic analysis; study linear and nonlinear problems; and analyze structures, fluids, electromagnetics, etc. Performing CAE analysis on the door assembly, for example, simulating the application of a Z-axis torque of 100 N.M at the door lock of the door assembly, and obtaining the coordinates and deformation amounts of several deformation points on the door assembly through CAE analysis.

[0047] The sheet metal deformation points that meet the preset conditions in the CAE analysis results are designated as sheet metal weak points. In some embodiments, the preset condition is that, under the condition of simulating a Z-axis torque of 100 N.M at the door lock of the door assembly, sheet metal deformation points with a deformation amount greater than 3.5 mm are designated as sheet metal weak points. The coordinates of the corresponding sheet metal weak points are obtained. In some embodiments, there may be one, two, or more sheet metal weak points. A dial indicator is installed at the corresponding sheet metal weak point location for subsequent physical testing. The sheet metal deformation amount obtained from the physical testing is analyzed and compared with the sheet metal deformation amount obtained from the CAE analysis, thereby continuously optimizing the CAE analysis method and improving the accuracy of CAE analysis.

[0048] In some embodiments, applying a Z-axis torque to the force transmission connector specifically includes: connecting the force-applying member to the force transmission connector and rotating the force-applying end of the force-applying member to generate a Z-axis torque.

[0049] To improve the accuracy of force application, in some embodiments, the force-applying component is a torque wrench, also known as a torque-adjustable wrench, which is a type of wrench. Using a torque wrench allows the operator to apply a specific torque value. That is, a specific torque value can be applied according to the actual test conditions, such as a specific torque value within the range of 100 N.M-150 N.M, which can be 100 N.M, 125 N.M, or 150 N.M, etc. This torque value corresponds to the torque value selected through CAE analysis, ensuring the accuracy of the comparison between the physical test data and the CAE analysis test data.

[0050] Example 2

[0051] Based on the same inventive concept, see Appendix Figure 2 To be continued Figure 5 This application also provides a test fixture for implementing the above-mentioned door bending stiffness test method, including: a force transmission connector 3, including a cantilever 32, a force-bearing nut 33, and a connecting plate 31 for connecting the door lock of the door assembly; the cantilever 32 is horizontally arranged on one side of the connecting plate 31 and perpendicular to the connecting plate 31; the force-bearing nut 33 is fixedly arranged on the cantilever 32 and is used to connect with the force-applying component to apply the Z-direction torque; a test bench 2, including a base, a door fixing column 21 for mounting the door assembly, and a door support column 22 for supporting the door assembly; the door fixing column 21 and the door support column 22 are arranged side by side and are both installed on the base; the door support column 22 is provided with a limiting mechanism for limiting the door assembly 1.

[0052] Before conducting the physical test of the door bending rigidity, the door assembly 1 needs to be fixed on the test bench 2 according to the vehicle posture. In some embodiments, the distance between the door fixing column 21 and the door support column 22 can be adjusted according to the lateral length of the door assembly 1. The hinge of the door assembly 1 is installed on the door fixing column 21, and the door lock end of the door assembly 1 is placed on the door support column 22. The door lock end of the door assembly 1 is limited by the limiting mechanism 26. Limiting by the limiting mechanism 26 can reduce the risk of the door assembly 1 rotating during the physical test, reduce the misalignment of the door assembly 1, and improve the accuracy of the subsequent test results. Install the force transmission connector 3 at the door lock of the door assembly 1, and install the connecting plate 31 against the side wall of the door lock of the door assembly 1. The connecting plate 31 can be installed on the side wall of the door lock of the door assembly 1 using bolt fasteners. Different connecting plates 31 can be selected according to different models to meet the requirements of the connecting holes 34 on the connecting plate 31 to meet the installation hole requirements of the door lock of the door assembly 1 on different models.

[0053] To facilitate the setup of corresponding dial gauges 24 according to actual test points in practical experiments, please refer to the appendix. Figure 6 In some embodiments, the test bench 2 is also provided with mounting columns 23 for mounting dial gauges 24. The position of the dial gauges 24 is determined by the test points, and the mounting columns 23 are then mounted on the base. This allows for the convenient arrangement of the appropriate number of dial gauges 24 according to the actual test points, mounting the dial gauges 24 on the mounting columns 23, and placing the front end of the dial gauges 24 in contact with the test points to obtain the deformation of the test points.

[0054] In some embodiments, the mounting column 23, the door fixing column 21, and the door support column 22 are all detachably connected to the base. In some embodiments, the mounting column 23, the door fixing column 21, and the door support column 22 can all be detachably connected to the base by bolts or fasteners, which facilitates adjusting the position of the mounting column 23, the door fixing column 21, and the door support column 23 on the base. The detachable connection between the door fixing column 21 and the door support column 22 and the base can meet the needs of connecting and installing multi-size door assemblies with the door fixing column 21 and the door support column 22. The detachable connection between the mounting column 23 and the base can adjust the position of the dial indicator 24 according to different test points to meet the needs of door bending rigidity testing.

[0055] To ensure that the physical test corresponds to the test points of the CAE analysis, one or more mounting columns 23 can be set, and dial gauges 24 are installed on the mounting columns 23. In some embodiments, one or more dial gauges 24 can be installed on one mounting column 23. If two test points are on a vertical line, two dial gauges 24 used for testing can be installed on the same mounting column 23 at the positions of the test points. The mounting column 23 is connected to the base with bolts and fasteners according to the actual test point position. After the front end of the dial gauge 24 contacts the test point, the sheet metal deformation of the test point is obtained.

[0056] In some embodiments, if the two test points are not on a vertical line, two dial indicators 24 for testing can be installed on the mounting column 23 corresponding to the positions of the test points. The two mounting columns 23 are connected to the base with bolts according to the actual positions of the test points. The sheet metal deformation of the test point is obtained after the front end of the dial indicator 24 contacts the test point.

[0057] To further improve the accuracy of experimental data in physical tests, after applying a Z-axis torque at the lock position of the door assembly 1, the door assembly 1 is prevented from rotating, reducing the impact of misalignment on the physical test of door bending rigidity. In some embodiments, the limiting mechanism 26 is a limiting groove for accommodating the bottom of the lock end of the door assembly 1. This limiting groove can be a V-shaped groove, a U-shaped groove, or a D-shaped groove. In some embodiments, after applying a Z-axis torque at the lock position of the door assembly 1, the limiting groove can limit the bottom of the lock end of the door assembly 1, preventing the door assembly 1 from rotating. To a certain extent, this can eliminate the error caused by the rotation of the door assembly 1 on the physical test results.

[0058] To ensure the accuracy of torque test results, in some embodiments, the distance between the central axis of the stressed nut 33 and the connecting plate 31 is greater than the maximum radius of rotation required for the end of the force-applying member closest to the connecting plate 31. (See Appendix) Figure 7 Taking the torque wrench with the force-applying component 25 as an example, the torque wrench is divided into a head 251 and a handle 252. During use, the head 251 is applied to the force-bearing nut 33 with a preset torque value, such as 100 N.M, 125 N.M, or 150 N.M. After the torque wrench applies torque, the head 251 will generate a rotation radius r, and the handle will generate a rotation radius R. In order to ensure that the torque wrench can be used normally on the force transmission connector 3, that is, the torque wrench can apply the corresponding torque to the force-bearing nut 33, the distance between the central axis of the force-bearing nut 33 and the connecting plate 31 is greater than the maximum rotation radius required by the force-applying component 25, that is, it must be greater than the rotation radius r generated by the torque wrench head after the torque is applied normally. While ensuring the normal use of the torque wrench, the accuracy of the test results after the torque wrench applies torque to the force-bearing nut 33 is improved.

[0059] In some embodiments, see Appendix Figures 8 to 11 The connecting plate 31 has at least two connecting holes 34, and the positions of the connecting holes 34 correspond one-to-one with the mounting holes of the door assembly 1. When the door assembly 1 has two mounting holes, the connecting plate 31 has two connecting holes 34, and the positions of the two connecting holes 34 correspond to the positions of the mounting holes of the door assembly 1, which facilitates installation by bolt fasteners after aligning the positions of the connecting plate 31 with the mounting holes of the door assembly 1.

[0060] In other embodiments, when the number of mounting holes in the door assembly 1 is 3, the connecting plate 31 is provided with 3 connecting holes 34, and the positions of the 3 connecting holes 34 correspond to the positions of the mounting holes in the door assembly 1, so that the connecting plate 31 can be installed by bolt fasteners after the positions of the mounting holes in the door assembly 1 are aligned.

[0061] To ensure the connection stability of the force transmission connector 3 during testing, in some embodiments, the number of connecting holes 34 is three, and the connecting plate 31 has a triangular structure. The three connecting holes 34 are respectively located at the three corners of the connecting plate; all three corners of the connecting plate are chamfered. The triangular structure formed by the three connecting holes 34 provides greater stability than the straight line formed by two connecting holes 34. Furthermore, the chamfering at the three vertices of the connecting plate 31 not only facilitates installation and prevents hand injuries during installation, but also enhances the aesthetics after installation.

[0062] Through the above embodiments, this application has the following beneficial effects or advantages:

[0063] 1) By installing corresponding force-transmitting connectors at the door lock of the door assembly, it is ensured that in actual tests, a Z-axis torque is applied to the force-transmitting connectors so that the Z-axis torque acts on the door assembly through the force-transmitting connectors. This simulates the application of a Z-axis torque at the door lock of the door assembly in the actual test, and obtains the results of the actual test. The sheet metal deformation obtained from the actual test is analyzed and compared with the sheet metal deformation obtained from CAE analysis, so as to continuously optimize the CAE analysis method and improve the accuracy of CAE analysis.

[0064] 2) When conducting the door bending rigidity test, the door assembly is fixed on the test bench according to the vehicle's posture. The distance between the door fixing column and the door support column is adjusted according to the lateral length of the door assembly. The hinge of the door assembly is installed on the door fixing column, and the door lock end of the door assembly is placed on the door support column. The door lock end of the door assembly is limited by a limiting mechanism. Limiting by the limiting mechanism can reduce the rotation of the door assembly during the test, which could cause the door assembly to be misaligned and affect the subsequent test results.

[0065] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0066] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for testing the bending stiffness of a car door, characterized in that, Includes the following steps: The door assembly is mounted on a test bench with a limiting mechanism in the same mounting position as the vehicle assembly, and the limiting mechanism limits the door assembly. A force-transmitting connector is installed at the door lock of the door assembly. The force-transmitting connector includes a cantilever, a force-bearing nut, and a connecting plate for connecting the door lock of the door assembly. The cantilever is horizontally arranged on one side of the connecting plate and perpendicular to the connecting plate. The force-bearing nut is fixedly arranged on the cantilever and is used to mate with the force-applying component to apply Z-axis torque. A Z-axis torque is applied to the force transmission connector so that the Z-axis torque acts on the door assembly through the force transmission connector; The deformation of the test points on the door assembly is obtained, and the test points are the sheet metal weak points obtained by CAE analysis.

2. The door bending stiffness test method as described in claim 1, characterized in that, Before obtaining the deformation at the test points on the door assembly, the door bending stiffness test method further includes: Install dial indicators on the test bench in the same number as the number of test points. Adjust the position of the dial indicators so that the position of the dial indicator corresponds one-to-one with the position of the test point, and the front end of the dial indicator contacts the corresponding test point.

3. The door bending stiffness test method as described in claim 1, characterized in that, Sheet metal weak points identified through CAE analysis specifically include: CAE analysis was performed on the door assembly to obtain the test results; The sheet metal deformation points that meet the preset conditions in the CAE analysis results are taken as the sheet metal weak points.

4. The method for testing the bending stiffness of a car door as described in any one of claims 1-3, characterized in that, Applying a Z-axis torque to the force-transmitting connector specifically includes: Connect the force-applying component to the force-transmitting connector, and rotate the force-applying end of the force-applying component to generate a Z-axis torque.

5. A test fixture for implementing the door bending stiffness test method according to any one of claims 1-4, characterized in that, include: The force-transmitting connector, wherein the force-receiving nut of the force-transmitting connector is used to mate with the force-applying component to apply the Z-axis torque; The test bench includes a base, a door fixing column for mounting the door assembly, and a door support column for supporting the door assembly. The door fixing column and the door support column are arranged side by side and are both mounted on the base. The door support column is provided with a limiting mechanism for limiting the door assembly.

6. The door bending rigidity testing fixture as described in claim 5, characterized in that, The test bench is also equipped with a mounting column for mounting a dial indicator; the mounting column, the door fixing column, and the door support column are all detachably connected to the base.

7. The door bending rigidity testing fixture as described in claim 6, characterized in that, The limiting mechanism is a limiting groove for accommodating the bottom of the door assembly.

8. The door bending rigidity testing fixture as described in any one of claims 5-7, characterized in that, The distance between the central axis of the stressed nut and the connecting plate is greater than the maximum rotation radius required for the force-applying component to be closer to the end of the connecting plate.

9. The door bending rigidity testing fixture as described in any one of claims 5-7, characterized in that, The connecting plate has at least two connecting holes, and the positions of the connecting holes correspond one-to-one with the mounting holes of the door assembly.

10. The door bending rigidity testing fixture as described in claim 9, characterized in that, The number of connecting holes is 3; the connecting plate has a triangular structure, and the 3 connecting holes are respectively located at the three corners of the connecting plate; all three corners of the connecting plate are chamfered.

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