Detection method for collision safety of automobile threshold assembly

Abstract

The invention discloses a method for detecting the collision safety of an automobile threshold assembly, and the method comprises the following steps: a, installing the threshold assembly at the upper parts of two supporting rollers of a high-speed drop hammer testing machine, and placing a drop hammer above the middle position of the two supporting rollers; b, releasing the falling mallet, and recording the stress of the threshold assembly and the displacement of the collision point in the collision process by the high-speed falling mallet testing machine; c, the average acting force borne by the automobile threshold assembly in the whole collision process is calculated according to the force-displacement curve; d, the bending moment borne by the threshold assembly is calculated; e, calculating the average value of the bending moments borne by the threshold assembly obtained by the three tests; and f, judging the collision safety of the threshold assembly according to the average value of the bending moment. According to the invention, the bending moment is used for representing the collision safety performance of the automobile threshold assembly, and the test error caused by inaccurate collection of a single instantaneous value is effectively avoided. Compared with a traditional method, the method has the advantages that the detection cost is low, and the accuracy of a detection result is greatly improved.

Description

Technical Field

[0001] The invention relates to a method for detecting the collision safety of an automobile door sill assembly by adopting a bending moment method, and belongs to the technical field of detection. Background Art

[0002] The door sill assembly is a key load-bearing component of the automobile body and plays a key role in head-on and side collisions. With the improvement of automobile lightweight and safety requirements, the safety requirements for the door sill assembly are getting higher and higher. How to accurately detect the collision safety of the door sill assembly is an urgent problem to be solved.

[0003] At present, there are two main methods for testing the collision safety of the threshold assembly: one is to use the intrusion amount of the threshold assembly in the collision of the whole vehicle as an evaluation index. This method is costly and is mainly used to comprehensively evaluate the collision safety of the whole vehicle; the other is to use a high-speed drop hammer tester to perform a three-point bending test on the threshold assembly, using the total depression amount or maximum collision force of the threshold assembly as an evaluation index. Due to the high speed of the high-speed drop hammer, it is difficult to accurately collect the maximum depression amount and maximum collision force of the threshold assembly, resulting in low detection accuracy and poor repeatability of this method. Therefore, it is very necessary to seek a collision safety detection method for automobile threshold assemblies with high detection accuracy and low cost. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting the collision safety of an automobile door sill assembly in view of the drawbacks of the prior art, so as to improve the detection accuracy and reduce the detection cost.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A method for detecting collision safety of a vehicle door sill assembly, the method comprising the following steps:

[0007] a. Install the welded automobile door sill assembly on the upper part of two mutually parallel support rollers on the test bench of the high-speed drop hammer tester, and place the drop hammer of the drop hammer tester above the middle position of the two support rollers;

[0008] b. Release the hammer, which falls freely and collides with the door sill assembly. The high-speed hammer tester records the force of the door sill assembly and the displacement of the collision point during the entire collision process to obtain a force-displacement curve;

[0009] c. Calculate the average force F that the vehicle door sill assembly is subjected to during the entire collision process based on the obtained force-displacement curve mean :

[0010]

[0011] Where f(x) is the force on the vehicle threshold assembly when the displacement of the collision point of the vehicle threshold assembly is x, Smax is the maximum displacement of the collision point of the vehicle door sill assembly;

[0012] d. Calculate the bending moment M on the vehicle door sill assembly b :

[0013] M b =(F mean ×Sp / 2) / 2

[0014] Where Sp is the distance between the two support axes;

[0015] e. Repeat steps a to d three times and calculate the average value of the bending moment of the vehicle door sill assembly obtained from the three tests.

[0016] f. Based on the average value of the bending moment of the vehicle door sill assembly Determine the collision safety of the vehicle threshold assembly, The larger it is, the higher the safety performance is. The smaller it is, the lower the safety performance.

[0017] In the above-mentioned method for detecting the collision safety of the automobile door sill assembly, the distance between the two support rollers on the test bench of the high-speed drop hammer test machine is 800 mm, and the horizontal distance between the B-pillar in the automobile door sill assembly and one of the support rollers is 90 mm.

[0018] In the above-mentioned method for detecting the collision safety of the automobile door sill assembly, the drop hammer of the drop hammer tester is a columnar body with a diameter of Φ110mm and a mass of 40Kg to 80Kg, and the drop hammer is located above the middle position of the two support rollers.

[0019] In the above-mentioned method for detecting the collision safety of the automobile door sill assembly, the height of the falling hammer relative to the automobile door sill assembly is 9.8m.

[0020] The present invention uses a high-speed drop hammer tester to perform a high-speed collision bending test on the automobile door sill assembly. According to the force-displacement curve obtained in the test, the bending moment of the door sill assembly is calculated by the integration method, and the magnitude of the bending moment is used to characterize the collision safety performance of the automobile door sill assembly, effectively avoiding the test error caused by the inaccurate collection of a single instantaneous value. Compared with the traditional method, this method not only has a low detection cost, but also greatly improves the accuracy of the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Figure 1 This is a diagram of the placement position of the automobile door sill assembly of the present invention before the experiment;

[0023] Figure 2 It is a force diagram of the automobile door sill assembly of the present invention;

[0024] Figure 3 It is the force-displacement curve of the threshold outer panel material DP980-1.6mm;

[0025] Figure 4 It is the force-displacement curve of the door sill outer panel material of DP1180-1.4mm.

[0026] The numbers in the figure are as follows: 1. support roller, 2. drop hammer, 3. vehicle door sill assembly, 4. B-pillar.

[0027] The symbols in the figures and text are as follows: F mean , the average force on the vehicle threshold assembly during the entire collision process; f(x) is the force on the vehicle threshold assembly when the displacement of the collision point of the vehicle threshold assembly is x, S max M is the maximum displacement of the collision point of the vehicle door sill assembly; b is the bending moment of the automobile door sill assembly; Sp is the distance between the two supporting axes; It is the average value of the bending moment acting on the vehicle door sill assembly. DETAILED DESCRIPTION

[0028] The present invention adopts a high-speed drop hammer tester to perform a three-point bending test on the automobile door sill assembly, and uses the force-displacement curve obtained by the high-speed drop hammer tester to calculate the bending moment received by the door sill assembly during the test. The greater the bending moment, the stronger the ability of the door sill assembly to resist bending, thereby solving the current problem of being unable to accurately evaluate the collision safety of the door sill assembly, and has the advantages of high measurement accuracy, simple operation, low cost, etc.

[0029] The present invention comprises the following steps:

[0030] (1) The welded automobile threshold assembly is installed on the upper part of two mutually parallel support rollers on the test bench of the high-speed drop hammer test machine. The distance between the two support rollers is 800mm. The horizontal distance between the B-pillar in the automobile threshold assembly and one of the support rollers is 90mm, which is used to locate the position of the threshold assembly on the test bench to ensure that the main force position of the B-pillar is consistent with the actual position of the vehicle collision. The drop hammer of the drop hammer test machine is a columnar body with a diameter of Φ110mm and a mass of 40Kg to 80Kg. The drop hammer is located above the middle position of the two support rollers. In order to make the initial velocity of the drop hammer colliding with the automobile threshold assembly consistent with the velocity of the vehicle collision, according to the vehicle collision velocity v = 50km / h (i.e. 13.88mm / s), the height H of the drop hammer relative to the automobile threshold assembly is calculated:

[0031]

[0032] Where g is the acceleration due to gravity;

[0033] (2) releasing the hammer, which falls freely and collides with the door sill assembly of the automobile. When the hammer is 300 mm away from the door sill assembly of the automobile, the acquisition system is triggered, and at the same time, a high-speed camera is triggered to take pictures, recording the force of the door sill assembly of the automobile and the displacement of the collision point during the entire collision process, and obtaining a force-displacement curve;

[0034] (3) Calculate the average force F applied to the vehicle door sill assembly during the entire collision process based on the force-displacement curve mean :

[0035]

[0036] Where f(x) is the force on the vehicle threshold assembly when the displacement of the collision point of the vehicle threshold assembly is x, S max is the maximum displacement of the collision point of the vehicle door sill assembly;

[0037] (4) Calculate the bending moment M of the vehicle door sill assembly b :

[0038] M b =(F mean ×Sp / 2) / 2

[0039] Where Sp is the distance between the two support axes;

[0040] (5) Repeat steps (1) to (4) three times and calculate the average value of the bending moment of the vehicle door sill assembly obtained from the three tests. Obtain parameters that characterize the collision safety of the vehicle door sill assembly;

[0041] (6) Based on the average bending moment of the vehicle door sill assembly Determine the collision safety of the vehicle threshold assembly, The larger the value, the greater the torque the vehicle door sill assembly is subjected to when it is bent, the stronger its ability to resist bending deformation, and the higher its safety performance. The smaller it is, the smaller the torque the vehicle door sill assembly is subjected to when it bends, the weaker its ability to resist bending deformation, and the lower its safety performance.

[0042] The present invention uses a high-speed drop weight test bench and a bending moment to evaluate the collision safety performance of an automobile door sill assembly. It has the advantages of simple operation, low cost, and high measurement accuracy, and solves the current problem of being unable to accurately characterize the collision safety of an automobile door sill assembly.

[0043] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings.

[0044] This embodiment is to calculate the bending moment of the automobile door sill assembly. The material of the door sill inner plate is DP980 with a thickness of 1.0 mm, and the material of the door sill outer plate is DP980-1.6 mm and DP1180-1.4 mm.

[0045] The test steps are:

[0046] (1) The welded automobile door sill assembly is mounted on the upper part of two mutually parallel support rollers on the test bench of the high-speed drop hammer tester. The diameter of the support roller is Φ40 mm, and the distance between the two support rollers is 800 mm. The horizontal distance between the B-pillar of the automobile door sill assembly and one of the support rollers is 90 mm. The drop hammer of the drop hammer tester is a columnar body with a diameter of Φ110 mm and a mass of 80 kg. The drop hammer is located above the middle position of the two support rollers. In order to make the initial velocity of the drop hammer hitting the automobile door sill assembly consistent with the collision velocity of the whole vehicle, according to the vehicle collision velocity v = 50 km / h (i.e. 13.88 mm / s), the height H of the drop hammer relative to the automobile door sill assembly is calculated as follows:

[0047]

[0048] Where g is the acceleration due to gravity;

[0049] (2) The hammer falls freely from a height of 9.8 mm. When it is 300 mm away from the workpiece, the acquisition system is triggered and the high-speed camera is triggered to take pictures. The force-displacement curve is measured during the whole process using the high-speed hammer test machine. Figure 2 and Figure 3 The experiment was repeated three times as shown;

[0050] (3) Based on Figure 2 and Figure 3 The force-displacement curve is used to calculate the average force F that the vehicle door sill assembly is subjected to during the entire collision process. mean :

[0051]

[0052] Where f(x) is the force on the vehicle threshold assembly when the displacement of the collision point of the vehicle threshold assembly is x, S max is the maximum displacement of the collision point of the vehicle door sill assembly;

[0053] (4) The stress condition of the vehicle door sill assembly is as follows: Figure 1 As shown, the bending moment M b The expression of M b =(F mean ×Sp / 2) / 2, where Sp is the distance between the two support rollers. The Sp used in this experiment is 800mm;

[0054] (5) The key test parameters obtained by the above two schemes are shown in Table 1.

[0055] Table 1 Key parameters obtained from the drop weight test

[0056]

[0057] The bending moment M obtained from the three experiments b Take the average value to get the result that represents the strength of the vehicle door sill assembly collision safety When the material of the threshold outer panel is DP980-1.6mm, the bending moment M b is 3.866N·m. When the material of the threshold outer panel is DP1180-1.4mm, the bending moment M b It is 4.307Mb. It can be seen that the collision safety performance has been improved to a certain extent by using DP1180-1.4mm instead of the original DP980-1.6mm, and the purpose of lightweight has been achieved.

Claims

1. A method for detecting the collision safety of a vehicle door sill assembly, characterized in that: The method comprises the following steps: a. Install the welded automobile door sill assembly on the upper part of two mutually parallel support rollers on the test bench of the high-speed drop hammer tester, and place the drop hammer of the drop hammer tester above the middle position of the two support rollers; b. Release the hammer, which falls freely and collides with the door sill assembly. The high-speed hammer tester records the force of the door sill assembly and the displacement of the collision point during the entire collision process to obtain a force-displacement curve; c. Calculate the average force F that the vehicle door sill assembly is subjected to during the entire collision process based on the obtained force-displacement curve mean : Where f(x) is the force on the vehicle threshold assembly when the displacement of the collision point of the vehicle threshold assembly is x, S max is the maximum displacement of the collision point of the vehicle door sill assembly; d. Calculate the bending moment M on the vehicle door sill assembly b : M b =(F mean ×Sp / 2) / 2 Where Sp is the distance between the two support axes; e. Repeat steps a to d three times and calculate the average value M of the bending moment of the vehicle door sill assembly obtained from the three tests. b ; f. Based on the average value of the bending moment M on the vehicle door sill assembly b Determine the collision safety of the vehicle threshold assembly, M b The larger the value, the higher the safety performance. b The smaller it is, the lower the safety performance.

2. A method for detecting collision safety of a vehicle door sill assembly according to claim 1, characterized in that: The distance between the two support rollers on the test bench of the high-speed drop hammer test machine is 800 mm, and the horizontal distance between the B-pillar and one of the support rollers in the vehicle door sill assembly is 90 mm.

3. A method for detecting collision safety of a vehicle door sill assembly according to claim 1 or 2, characterized in that: The drop hammer of the drop hammer tester is a columnar body with a diameter of Φ110 mm and a mass of 40 kg to 80 kg. The drop hammer is located above the middle position of the two support rollers.

4. A method for detecting collision safety of a vehicle door sill assembly according to claim 3, characterized in that: The height of the hammer relative to the vehicle door sill assembly is 9.8 m.

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