Vehicle body structure reinforcing member rigidity test bench, test system and test method

Abstract

The invention belongs to the field of vehicle body structure design, and discloses a vehicle body structure reinforcement rigidity test bench, test system and test method.The vehicle body structure reinforcement rigidity test bench comprises a rigid bench, a load applying device and a displacement measuring device, the load applying device and the displacement measuring device are both arranged on the rigid bench, and the load applying device is used for applying a load to a test piece; and the displacement measuring device is used for measuring a displacement value generated by the test piece under the action of the applied load. According to the invention, a test object is converted from a whole body in white into a combination of a single reinforcement and a substrate through a simple vehicle body structure reinforcement rigidity test bench and a quantitative index, the index of rigidity contribution degree is introduced, the rigidity contribution degree of the reinforcement can be rapidly and accurately evaluated through comparison test and calculation, the method is visual and easy to implement, and the method is suitable for large-scale popularization and application. A key basis is provided for early-stage design optimization and quality control, the rigidity improvement effect of the reinforcement part on the local structure of the vehicle body is accurately quantified, meanwhile, the development period is greatly shortened, and the research and development cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of vehicle body structure design, and particularly relates to a vehicle body structure reinforcement rigidity test bench, a test system and a test method. BACKGROUND

[0002] In recent years, with the increasing requirements of the automobile industry for lightweight, safety and energy consumption, high-strength steel, aluminum alloy and other materials are increasingly widely used in vehicle body manufacturing, and the structure design is becoming more and more complex. In order to achieve higher performance indicators, local reinforcement technology is generally used in vehicle body design, that is, by means of structural bonding, spot welding or mechanical connection, etc., reinforcing plates, stiffeners or closed beams and other structural reinforcements are installed in key stress areas (such as A-pillar, B-pillar, rocker beam, longitudinal beam, etc.). This design concept of "global lightweight and local strengthening" has become a key means to improve the overall stiffness of the vehicle body, improve the safety in collision and NVH (noise, vibration and harshness) performance. However, the widespread use of structural reinforcements also brings a series of new technical challenges. The most core problem is how to accurately and efficiently evaluate the actual effect of a single reinforcement.

[0003] At present, the industry generally relies on the test of bending stiffness and torsional stiffness of the complete body-in-white to indirectly verify the design. This traditional method has significant limitations: first, the overall stiffness is the result of the joint action of thousands of parts, and the test data cannot accurately trace the specific contribution value of a particular reinforcement, making it difficult to judge the design and unclear the improvement direction. Second, this method must rely on a complete physical sample vehicle, which has a long verification period and high cost, and cannot quickly screen and iteratively optimize multiple reinforcement schemes in the early stages of design and trial production, which seriously affects the research and development efficiency. In actual production, due to the lack of effective part-level evaluation methods, the design and selection of reinforcements often rely on the experience of engineers or computer simulation. Although simulation analysis can provide guidance, the results still need to be verified by physical tests. If the performance of the reinforcement does not meet expectations, it may lead to insufficient local stiffness of the vehicle body, causing a series of quality problems: in the process of vehicle use, it may manifest as a dull sound when closing the door, abnormal noise of the vehicle body, strong loose feeling when driving, which seriously affects user experience and brand image; more seriously, in extreme working conditions or collision accidents, insufficient local stiffness may cause the structure to lose stability prematurely, posing a threat to the safety of passengers. On the contrary, if the design is too conservative, it will cause waste of materials and cost, which goes against the original intention of lightweight. Therefore, it is urgent to establish a special test method that can quickly and accurately quantify the structural reinforcement stiffness contribution at the part level. SUMMARY

[0004] The purpose of the present application is to provide a vehicle body structure reinforcement rigidity test bench, test system and test method, through simple vehicle body structure reinforcement rigidity test bench and quantitative index, the test object is changed from the whole body-in-white to the combination of single reinforcement and substrate, the index of rigidity contribution is introduced, through comparison test and calculation, the rigidity contribution of the reinforcement can be quickly and accurately evaluated, the method is intuitive and easy to implement, which provides key basis for early design optimization and quality control, accurately quantifies the rigidity improvement effect of the reinforcement on the local structure of the vehicle body, and greatly shortens the development cycle and reduces the research and development cost.

[0005] The specific scheme content is as follows:

[0006] A vehicle body structure reinforcement rigidity test bench for testing the rigidity of a vehicle body structure reinforcement, comprising a rigid bench, a load applying device and a displacement measuring device, the load applying device and the displacement measuring device are arranged on the rigid bench, the load applying device is used to apply a load to the test piece, and the displacement measuring device is used to measure the displacement value of the test piece under the action of the applied load.

[0007] The vehicle body structure reinforcement rigidity test bench designed by the present application is composed of a rigid bench, a load applying device and a displacement measuring device, the rigid bench comprises a rigid base, and the material and thickness of the reference plate need to be consistent with the actual plate of the vehicle body. The reference plate and the reinforcement are fixed on the reference plate by an actual process (such as structural bonding) to form a test piece, i.e. a reinforcement assembly. The fixture is arranged on the rigid base and is used to position and clamp the test piece. The displacement measurement accuracy needs to reach 0.01mm, and the load measurement accuracy needs to reach 1N. Compared with the existing indirect method which depends on vehicle test, the core improvement of the present application is that the test object is changed from the whole body-in-white to the combination of single reinforcement and substrate, and the index of "rigidity contribution" is introduced to realize accurate quantitative evaluation. This improvement makes it unnecessary to manufacture a complete sample vehicle for research and development, and accurate data can be obtained quickly and at low cost in the early stage of design through simple bench, so as to greatly shorten the development cycle, reduce the research and development cost, and provide a unified and fair comparison benchmark for different design schemes.

[0008] Further, the rigid bench comprises a rigid base, a reference plate and a clamp, the reference plate is used for fixed connection with the reinforcement to form a test piece, and the clamp is arranged on the rigid base and is used to position and clamp the test piece.

[0009] Further, the load applying device comprises an actuator, a loading ram and a bracket, the bottom of the bracket is fixedly connected to the rigid bench, the actuator is arranged at the top of the bracket and is used for output of load power, and the loading ram is arranged at the bottom of the actuator and is used as an execution end for load transmission and adaptation and directly acts on the test piece.

[0010] The support of the load applying device is fixedly installed on one side of the rigid base, the actuator is arranged on the top of the support, and the bottom of the actuator is provided with a loading ram.

[0011] Further, the displacement measuring device comprises a displacement sensor arranged on the support between the loading ram and the reference plate and used for measuring the displacement value of the test piece under the action of the applied load.

[0012] The displacement measuring device preferably comprises a displacement sensor fixed on the support and located between the loading ram and the reference plate.

[0013] The body structure reinforcement rigidity test system comprises the body structure reinforcement rigidity test bench and further comprises a computer control unit.

[0014] The body structure reinforcement rigidity test system comprises the body structure reinforcement rigidity test bench and further comprises a computer control unit.

[0015] A body structure reinforcement rigidity test method is provided.

[0016] S1, preparation of a test piece: the test piece is a reinforcement assembly comprising a reinforcement and a reference plate, the reinforcement is fixed on the reference plate, and the material and thickness of the reference plate are consistent with those of an actual body plate;

[0017] S2, setting of a test bench condition: the boundary condition of the body structure reinforcement rigidity test bench is set to simulate an actual vehicle installation state, the load loading mode of the actuator is a concentrated load, and the action point of the loading ram is located in the coverage area of the reinforcement.

[0018] S3, testing: first, test the reference plate, apply concentrated load at a preset rate, measure displacement δ_base, and send the data to the computer control unit, which synchronously records the load value and displacement value; then test the reinforcement assembly, apply load F under the same conditions, measure displacement δ_assembly; repeat the test three times, and send the data to the computer control unit, which synchronously records the load value and displacement value; the computer control unit draws a load-displacement curve according to the received load value and displacement value, and takes the data with the best linearity for calculation; the computer control unit calculates the stiffness value K_base of the reference plate and the stiffness value K_assembly of the reinforcement assembly according to the preset stiffness calculation program, and then calculates the stiffness contribution degree η;

[0019] S4, evaluation: according to the grading standard of the stiffness contribution degree η, the grading evaluation of the test piece is carried out, and the grading standard of the stiffness contribution degree η is:

[0020] Excellent level: η≥50%

[0021] Good level: 30%≤η<50%

[0022] Qualified level: 15%≤η<30%

[0023] Need to improve level: η<15%;

[0024] S5, result verification: the verification method uses repeatability verification, that is, the same reinforcement is tested three times, and the coefficient of variation of the stiffness contribution degree η should be less than 5%.

[0025] When testing using the test method of the application,

[0026] First, prepare the test piece: the test piece is a reinforcement assembly, including a reinforcement and a reference plate, the reinforcement is fixed on the reference plate, and the material and thickness of the reference plate are consistent with the actual plate of the vehicle body;

[0027] Then, set the test bench conditions: the boundary conditions of the test bench simulate the actual vehicle installation state, and the load loading mode of the actuator is concentrated load, and the action point of the loading pressure head is located in the reinforcement coverage area;

[0028] The purpose of setting the test bench conditions is:

[0029] Work condition restoration authenticity: by simulating the actual vehicle installation boundary conditions, the differences between the test environment and the actual vehicle working condition are eliminated, the test results can truly reflect the actual stress state of the parts in the vehicle power system, and the performance evaluation deviation caused by the distortion of the boundary conditions is avoided.

[0030] Accuracy of load simulation: By adopting a concentrated load loading method, the local concentrated stress scenarios that components may experience during actual vehicle operation (such as the connection between the reinforcement and the base, and key load-bearing areas) are specifically simulated to accurately assess the load resistance of the structure.

[0031] Targeted verification of reinforcement effects: The application point of the loading head is limited to the area covered by the reinforcement, focusing on verifying the core functions of the reinforcement, including the strengthening and support effect on the key stress areas of the components, the resistance to deformation, the improvement of fatigue life, and the reliability of the connection between the reinforcement and the substrate (such as avoiding failure risks such as peeling and cracking), providing direct data support for the structural design optimization and manufacturing process improvement of the reinforcement.

[0032] Scientific nature of performance evaluation: By setting up standardized and reproducible test conditions, the repeatability and comparability of test data are ensured, providing a scientific basis for the qualification of components and the overall reliability verification of the power system, and supporting product R&D iteration and mass production quality control.

[0033] The core objective of this setup is to provide comprehensive and practical testing support for the structural reliability and performance compliance of key powertrain components (including reinforcements) through the logic of "operating condition restoration - load precision - effect focus," thereby ensuring their safety, durability, and stability during vehicle operation.

[0034] Test steps:

[0035] Mount the test specimen on the test bench, ensuring the boundary conditions meet the simulation requirements. Apply a concentrated load at a rate of 1 mm / min, simultaneously recording the load and displacement values. Repeat the test three times, using the data showing the best linearity for calculation.

[0036] Data processing:

[0037] The computer control unit plots load-displacement curves based on the received load and displacement values, and selects the linear segment (R²≥0.95) for calculation. The stiffness values ​​of the reference plate and the reinforcement assembly are calculated separately, and finally, the stiffness contribution is calculated.

[0038] Results validation methods include repeatability validation and accuracy validation:

[0039] The specific methods for repeatability verification are as follows:

[0040] The coefficient of variation of stiffness contribution should be less than 5% when the same reinforcement is tested three times repeatedly.

[0041] The specific methods for accuracy verification are as follows:

[0042] Through finite element analysis and comparison, the error between the experimental results and the simulation results should be less than 10%.

[0043] Further, the measurement accuracy of displacement needs to reach 0.01mm, and the measurement accuracy of load needs to reach 1N.

[0044] Further, in step S3, the preset rigidity calculation program is calculated based on the calculation formula of rigidity value K: K = F / δ and the calculation formula of rigidity contribution degree η: η = (K_assembly - K_base) / K_base × 100%.

[0045] The core calculation method of the application is the calculation of rigidity contribution degree, and the calculation formula is:

[0046] Rigidity contribution degree η = (K_assembly - K_base) / K_base × 100%

[0047] K_base is the rigidity value of the reference substrate, and K_assembly is the rigidity value of the enhanced assembly (the combination of the substrate and the reinforcing part).

[0048] The rigidity value K is calculated by the following formula:

[0049] K = F / δ

[0050] F is the applied load value, and δ is the displacement value generated under the action of load F. The calculation is based on the linear segment of the load-displacement curve, and the linear segment (R² ≥ 0.95) is selected for calculation.

[0051] Further, in step S3, the calculation of rigidity value K is based on the load-displacement curve drawn by the computer control unit, and then the best value of the linear segment with R² ≥ 0.95 is selected for calculation.

[0052] The calculation of rigidity value K is based on the drawn load-displacement curve, and the linear segment with R² ≥ 0.95 is selected for calculation, so as to ensure the scientificity, accuracy and engineering practicability of rigidity calculation.

[0053] Further, in step S5, the verification method can also use accuracy verification, that is, through finite element analysis comparison verification, the error between the test result and the simulation result should be less than 10%.

[0054] The verification method of the application adopts repeatability verification, and also can adopt accuracy verification, which is used for verification of the test result of the application.

[0055] See Figure 2 The ideal reference plate and the load-displacement relationship curve of the enhanced assembly are shown in the ideal reference plate and the load-displacement relationship curve of the enhanced assembly, which clearly shows the principle of the application. In the figure, the straight line represents. The slope of the enhanced assembly F-δ curve is obviously larger than that of the reference plate F-δ curve, indicating that its rigidity is higher.

[0056] Compared with the prior art, the present application has the following beneficial effects:

[0057] Compared with the prior art, the present application has the following beneficial effects:

[0058] Compared with the prior art, the present application has the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 It is a schematic diagram of the body structure reinforcement rig of the present application.

[0060] Figure 2 It is a schematic diagram of the load-displacement relationship curve of the ideal reference plate and reinforcement assembly of the present application.

[0061] In the figure:

[0062] 1. rigid base; 2. reference plate; 3. clamp; 4. reinforcement; 5. actuator; 6. loading ram; 7. support; 8. displacement sensor. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative labor under the premise of the embodiments of the present application, belong to the scope of protection of the present application.

[0064] The terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Multiple" generally includes at least two.

[0065] It should be noted that the terms "front", "back", "inner", "outer", "left", "right" and the like in the present application indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0066] The present application will be described in detail below in conjunction with Figure 1 and Figure 2 The present application will be described in detail below in conjunction with

[0067] Example 1:

[0068] A vehicle body structure reinforcement rigidity test bench, as shown in Figure 1 for testing the rigidity of a vehicle body structure reinforcement, comprising a rigid bench, a load applying device and a displacement measuring device, the load applying device and the displacement measuring device are both arranged on the rigid bench, the load applying device is used to apply a load to the test piece, and the displacement measuring device is used to measure the displacement value of the test piece under the action of the applied load.

[0069] The rigid bench comprises a rigid base 1, a reference plate 2 and a clamp 3, the reference plate 2 is used to be fixedly connected with the reinforcement 4 to form a test piece, and the clamp 3 is arranged on the rigid base 1 and used to position and clamp the test piece.

[0070] The load applying device comprises an actuator 5, a loading ram 6 and a bracket 7, the bottom of the bracket 7 is fixedly connected to the rigid bench, the actuator 5 is arranged on the top of the bracket 7 and used to output load power, and the loading ram 6 is arranged on the bottom of the actuator 5 and used as an execution end for load transmission and adaptation and directly acts on the test piece.

[0071] The displacement measuring device comprises a displacement sensor 8, which is arranged on the bracket 7 between the loading ram 6 and the reference plate 2 and used to measure the displacement value of the test piece under the action of the applied load.

[0072] Example 2:

[0073] The present application also provides a vehicle body structure reinforcement rigidity test system, which comprises the vehicle body structure reinforcement rigidity test bench and a computer control unit, the computer control unit calculates the rigidity of the test piece by combining the received load value and displacement value of the test piece with a pre-set rigidity calculation program, the computer control unit is electrically connected with the load applying device and used to control the load applying device to apply a load to the test piece, and the computer control unit is electrically connected with the displacement measuring device and used to control the displacement measuring device to collect the displacement value and receive the measured displacement value information.

[0074] Example 3:

[0075] The application also provides a method for testing the rigidity of a vehicle body structure reinforcement, which applies the vehicle body structure reinforcement rigidity testing system to perform rigidity testing, and the steps include:

[0076] S1. Preparation of the test piece: the test piece is a reinforcement assembly, which includes a reference plate 2 and a reinforcement 4, and the reinforcement 4 is fixed to the reference plate 2, wherein the material and thickness of the reference plate 2 are consistent with the actual plate of the vehicle body; the two reference plates 2 sandwich the reinforcement 4 in the middle, and the reference plate 2 and the reinforcement 4 are adhesively fixed, as shown in FIG. 1. Figure 1

[0077] S2. Setting of the test bench conditions: the boundary conditions of the vehicle body structure reinforcement rigidity test bench are set to simulate the actual installation state of the vehicle, the load loading mode of the actuator 5 is a concentrated load, and the action point of the loading ram 6 is located in the coverage area of the reinforcement 4;

[0078] S3. Testing: first, test the reference plate 2, apply a concentrated load F at a preset rate, measure the displacement δ_base, and send the data to the computer control unit, which synchronously records the load value and the displacement value; then test the reinforcement assembly, apply the load F under the same conditions, and measure the displacement δ_assembly; repeat the test three times, and send the data to the computer control unit, which synchronously records the load value and the displacement value; the computer control unit draws a load-displacement curve according to the received load value and displacement value, and takes the data with the best linearity for calculation; the computer control unit calculates the rigidity value K_base of the reference plate 2 and the rigidity value K_assembly of the reinforcement assembly according to the preset rigidity calculation program, and further calculates the rigidity contribution degree η; the measurement accuracy of the displacement needs to reach 0.01 mm, and the measurement accuracy of the load needs to reach 1 N.

[0079] In S3, the preset rigidity calculation program calculates based on the calculation formula of the rigidity value K: K = F / δ, and the calculation formula of the rigidity contribution degree η: η = (K_assembly - K_base) / K_base × 100%.

[0080] In S3, the calculation of the rigidity value K is based on the computer control unit drawing a load-displacement curve, and then selecting the best value of the linear segment with R²≥0.95 for calculation.

[0081] S4. Evaluation: according to the grading standard of the rigidity contribution degree η, the grading evaluation of the test piece is performed, and the grading standard of the rigidity contribution degree η is:

[0082] Excellent level: η≥50%

[0083] Good level: 30%≤η<50% ​

[0084] Pass / Fail Grade: 15% ≤ η < 30%

[0085] Level requiring improvement: η < 15%;

[0086] S5. Result verification: The verification method adopts repeatability verification, that is, the same reinforcement 4 is tested three times repeatedly, and the coefficient of variation of stiffness contribution η should be less than 5%.

[0087] See Figure 2 The schematic diagram of the load-displacement relationship curves of the ideal reference plate and the reinforced assembly clearly illustrates the principle of the invention, represented by straight lines. The slope of the F-δ curve of the reinforced assembly is significantly greater than that of the reference plate's F-δ curve, indicating that it has higher stiffness.

[0088] Example 4:

[0089] This invention also provides a method for testing the stiffness of a vehicle body structural reinforcement component, which uses the aforementioned vehicle body structural reinforcement component stiffness testing system to perform stiffness testing, and includes the following steps:

[0090] S1. Preparation of test parts: The test parts are reinforcement assemblies, including a reference plate 2 and reinforcement 4. Reinforcement 4 is fixed on the reference plate 2. The material and thickness of the reference plate 2 must be consistent with the actual body panels.

[0091] S2. Setting the test bench conditions: Set the boundary conditions of the test bench for the stiffness of the body structure reinforcement to simulate the actual vehicle installation state. The load loading method of the actuator 5 is a concentrated load, and the point of application of the loading head 6 is located in the area covered by the reinforcement 4.

[0092] S3. Conduct the test: First, test the reference plate 2 by applying a concentrated load F at a preset rate, measuring the displacement δ_base, and sending the data to the computer control unit. The computer control unit simultaneously records the load and displacement values. Then, test the reinforcement assembly by applying a load F under the same conditions and measuring the displacement δ_assembly. Repeat the test three times and send the data to the computer control unit, which simultaneously records the load and displacement values. The computer control unit plots the load-displacement curve based on the received load and displacement values ​​and selects the data with the best linearity for calculation. The computer control unit calculates the stiffness value K_base of the reference plate 2 and the stiffness value K_assembly of the reinforcement assembly according to the preset stiffness calculation program, and then calculates the stiffness contribution η. The displacement measurement accuracy must reach 0.01mm, and the load measurement accuracy must reach 1N.

[0093] In S3, the preset rigidity calculation program calculates based on the calculation formula of the rigidity value K: K = F / δ and the calculation formula of the rigidity contribution degree η: η = (K_assembly - K_base) / K_base × 100%.

[0094] In S3, the calculation of the rigidity value K is based on the computer control unit drawing a load-displacement curve, and then selecting the best value of the linear segment with R²≥0.95 for calculation.

[0095] In S4, evaluation is performed: according to the grading standard of the rigidity contribution degree η, the grading evaluation of the test piece is performed, and the grading standard of the rigidity contribution degree η is:

[0096] Excellent level: η≥50%

[0097] Good level: 30%≤η<50%

[0098] Qualified level: 15%≤η<30%

[0099] Need to improve level: η<15%;

[0100] In S5, the result verification is performed: the verification method adopts accuracy verification, that is, comparison verification by finite element analysis, and the error between the test result and the simulation result should be less than 10%.

[0101] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A body structure reinforcement rigidity test bench for rigidity test of a body structure reinforcement, characterized by, The test bench comprises a rigid base, a load applying device and a displacement measuring device, the load applying device and the displacement measuring device are arranged on the rigid base, the load applying device is used to apply load to a test piece, and the displacement measuring device is used to measure the displacement value of the test piece under the action of the applied load.

2. The body structure reinforcement rigidity test bench of claim 1, wherein, The rigid base comprises a rigid base (1), a reference plate (2) and a clamp (3), the reference plate (2) is used to be fixedly connected with a reinforcing member (4) to form a test piece, and the clamp (3) is arranged on the rigid base (1) and used to position and clamp the test piece.

3. The body structure reinforcement rigidity test bench of claim 1, wherein, The load applying device comprises an actuator (5), a loading ram (6) and a bracket (7), the bottom of the bracket (7) is fixedly connected to the rigid base, the actuator (5) is arranged on the top of the bracket (7) and used to output load power, and the loading ram (6) is arranged on the bottom of the actuator (5) and used as an execution end for load transmission and adaptation and directly acts on the test piece.

4. The body structure reinforcement rigidity test bench of claim 1, wherein, The displacement measuring device comprises a displacement sensor (8), the displacement sensor (8) is arranged on the bracket (7) between the loading ram (6) and the reference plate (2) and used to measure the displacement value of the test piece under the action of the applied load.

5. A body structure reinforcement rigidity testing system characterized by, The test bench further comprises a computer control unit, the computer control unit is used to calculate the rigidity of the test piece by combining the received load value and displacement value of the test piece with a preset rigidity calculation program, the computer control unit is electrically connected with the load applying device and used to control the load applying device to apply load to the test piece, and the computer control unit is electrically connected with the displacement measuring device and used to control the displacement measuring device to collect the displacement value and receive the measured displacement value information.

6. A method of testing the rigidity of a body structure reinforcement, characterized in that, The test bench is applied to the rigidity test of the reinforcing member of the vehicle body structure, and the rigidity test comprises the following steps: S1, preparation of the test piece: the test piece is a reinforcing assembly, which comprises a reference plate (2) and a reinforcing member (4), the reinforcing member (4) is fixed to the reference plate (2), and the material and thickness of the reference plate (2) are consistent with those of the actual plate of the vehicle body; S2, setting of the test bench conditions: the boundary conditions of the test bench are set to simulate the installation state of the actual vehicle, the load applying mode of the actuator (5) is a concentrated load, and the action point of the loading ram (6) is located in the coverage area of the reinforcing member (4). S3, test: first, test the reference plate (2), apply concentrated load at a preset rate, measure the displacement δ_base, and send the data to the computer control unit, which records the load value and displacement value simultaneously; then test the reinforcement assembly, apply load F under the same conditions, measure the displacement δ_assembly; repeat the test three times, and send the data to the computer control unit, which records the load value and displacement value simultaneously; the computer control unit draws a load-displacement curve according to the received load value and displacement value, and takes the best linear data for calculation; the computer control unit calculates the stiffness value K_base of the reference plate (2) and the stiffness value K_assembly of the reinforcement assembly according to the preset stiffness calculation program, and then calculates the stiffness contribution degree η; S4, evaluation: according to the grading standard of the stiffness contribution degree η, the grading evaluation of the test piece is carried out, and the grading standard of the stiffness contribution degree η is: Excellent level: η≥50% Good level: 30%≤η<50% Qualified level: 15%≤η<30% Need to improve level: η<15%; S5, result verification: the verification method includes repeatability verification, i.e. three repeated tests are performed on the same reinforcement (4), and the coefficient of variation of the stiffness contribution degree η should be less than 5%.

7. The method of claim 6, wherein, The measurement accuracy of displacement should reach 0.01mm, and the measurement accuracy of load should reach 1N.

8. The method of claim 6, wherein, In step S3, the preset stiffness calculation program is based on the calculation formula of stiffness value K: K = F / δ and the calculation formula of stiffness contribution degree η: η = (K_assembly - K_base) / K_base × 100%.

9. The method of claim 6, wherein, In step S3, the calculation of stiffness value K is based on the computer control unit drawing a load-displacement curve, and then selecting the best value of the linear segment with R²≥0.95 for calculation.

10. The method of claim 6, wherein, In step S5, the verification method can also include accuracy verification, i.e. through finite element analysis comparison verification, the error between the test result and the simulation result should be less than 10%.

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