Automobile frame dynamic load testing method

Abstract

The invention discloses an automobile frame dynamic load test method, and relates to the field of automobile body design, and the method comprises the steps: installing a test tool provided with a buffer limiting block on an automobile frame; carrying out a vehicle pavement test to obtain an actual dependent variable of the test tool; and acquiring an actual dynamic load under the actual dependent variable based on the actual dependent variable and a mapping relationship between the pressure preset by the test tool and the dependent variable. By additionally arranging the testing tool, a measuring surface is provided for pressure measurement of the buffer limiting block, and the possibility that the testing tool exceeds an elastic deformation range after being pressed is reduced; moreover, the dynamic load which can be actually borne by the whole vehicle frame in the moving process of the vehicle can be reflected, so that the vehicle strength reinforcing range precision is improved, and the problems that in the prior art, the deformation of a certain point position on the vehicle frame is measured, detection data distortion is likely to occur, and the detection accuracy is poor are solved. And the actual load borne by the whole vehicle frame is difficult to directly reflect.

Description

Technical Field

[0001] The invention relates to the field of vehicle body design, and in particular to a method for testing dynamic load of an automobile frame. Background Art

[0002] During the development of new car models, the impact load from the road will be transmitted to the vehicle axle through the wheels, and then the leaf spring at the bottom of the vehicle axle will be used for shock absorption. During the leaf spring shock absorption process, the vehicle axle will bend vertically, resulting in a decrease in the relative distance between the vehicle frame and the vehicle axle. When the vehicle encounters excessive road impact during driving, the leaf spring will deform significantly. In order to prevent the leaf spring from deforming too much and breaking at one time, a buffer limit block will be installed on the opposite surface of the vehicle frame and the vehicle axle. The surface of the buffer limit block facing the vehicle axle cooperates with the surface of the vehicle axle. When the leaf spring deforms significantly and drives the vehicle axle to move toward the vehicle frame, the buffer limit block installed on the vehicle frame contacts the vehicle axle to limit the continuous movement of the vehicle axle.

[0003] In actual use, the dynamic load generated when the buffer limit block contacts the vehicle axle will be transmitted to the vehicle frame installation position through the buffer limit block. Therefore, the strength of the vehicle frame needs to be strengthened to reduce the possibility of local deformation of the vehicle frame due to insufficient strength. Usually when a new model is developed, the designer will generally strengthen the vehicle frame position where the buffer limit block is installed based on experience. In order to enhance the strength of the vehicle frame, the design of the vehicle frame is relatively redundant, which will lead to an increase in the cost and weight of the vehicle. If the strength is insufficient and the design is weak, it is easy to cause the vehicle to deform again. At the same time, the trial production and verification cycle of the improvement plan is long, which not only delays the development time, but also wastes trial production test resources. Therefore, it is necessary to collect the actual dynamic load range generated during the actual road test of the whole vehicle and carry out targeted design according to the actual load.

[0004] In the process of collecting the actual dynamic load of the vehicle, measurement strain gauges are usually pasted in the area of ​​the vehicle frame where the buffer limit block is installed to collect the actual strain during the vehicle road test. The maximum stress generated in the actual process is then calculated based on the actual strain and material elastic modulus.

[0005] However, in the process of measuring the deformation of a certain point on the vehicle frame, a single point is prone to local deformation during the vehicle bumping process. When the deformation of a certain point exceeds the elastic deformation range, no elastic deformation will occur, resulting in stress distortion detected at this time; and the dynamic load on a single point is difficult to reflect the actual load borne by the entire vehicle frame mounting surface, and can only represent the dynamic load on the measurement point. This measurement method is difficult to directly reflect the actual load transmitted to the vehicle frame, and can only give an approximate reference range, resulting in the subsequent vehicle frame strength enhancement range is still unclear. Summary of the invention

[0006] The present application provides a vehicle frame strain test device and a test method thereof, which can solve the technical problems existing in the prior art that when measuring the deformation of a certain point on the vehicle frame, the detection data is easily distorted and it is difficult to directly reflect the actual load on the entire vehicle frame.

[0007] The present application provides a method for testing the dynamic load of a vehicle frame, which includes:

[0008] Install the test fixture equipped with the buffer limit block on the vehicle frame;

[0009] Conducting a vehicle road test to obtain an actual strain amount of the test fixture;

[0010] Based on the actual strain amount and the mapping relationship between the pressure preset by the test fixture and the strain amount, the actual dynamic load under the actual strain amount is obtained.

[0011] In one embodiment, the automobile frame dynamic load test method further includes: obtaining a mapping relationship between a preset pressure of the test fixture and a strain amount;

[0012] Obtaining the mapping relationship between the preset pressure of the test fixture and the strain amount, which specifically includes:

[0013] Installing the buffer limit block to the surface of the test fixture;

[0014] Apply different pressures toward the buffer limit block to obtain the strain amount of the test tool surface under different pressures;

[0015] Based on the different applied pressures and the corresponding strain amounts, a mapping relationship between the pressure preset by the test fixture and the strain amount is obtained.

[0016] In one embodiment, before the buffer limit block is installed on the surface of the test fixture, the method further includes:

[0017] The buffer limit block is manufactured based on the surface shape of the axle of the vehicle to be tested, so that the buffer limit block is consistent with the curved surface shape of the axle surface of the vehicle to be tested.

[0018] In one embodiment, the test tool comprises:

[0019] A test base plate, wherein the cross-sectional dimension of the test base plate is greater than the cross-sectional dimension of the buffer limit block. When the buffer limit block is installed on the test base plate, a strain measurement space is formed between the buffer limit block and the edge of the test base plate in the length direction, and a measurement strain gauge is arranged on the strain measurement space.

[0020] In one embodiment, applying pressure toward the buffer limit block specifically includes:

[0021] Mounting the test base plate with the buffer limit block fixed thereto on a strain test device, and turning on the strain test device to apply pressure toward the buffer limit block;

[0022] The strain testing device specifically comprises:

[0023] A calibration platform is provided with a profiling pressure head, and a movable end of the profiling pressure head is adapted to the outer surface of the buffer limit block.

[0024] In one embodiment, obtaining the strain of the test tool surface under different pressures specifically includes:

[0025] Connecting a data acquisition instrument to the measuring strain gauge;

[0026] Simultaneously turning on the data acquisition instrument and the profiling pressure head to obtain the strain amount of the surface of the test base plate under different pressures when the strain amount testing device applies different pressures toward the buffer limit block;

[0027] Based on the real-time stress of the test base plate when it is subjected to different pressures, a stress curve of the pressure and strain of the test base plate is produced.

[0028] In one embodiment, the width of the strain measurement space is greater than or equal to 10 mm.

[0029] In one embodiment, fixed legs are provided on both sides of the test base plate in the length direction.

[0030] In one embodiment, the test base plate is made of a rigid metal material, and the strength of the test base plate is higher than the strength of the vehicle frame.

[0031] In one embodiment, installing the test base plate on the vehicle frame specifically includes:

[0032] The test base plate is detachably connected to the vehicle frame via bolts.

[0033] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0034] By adding a test fixture, a measuring surface is provided for the pressure measurement of the buffer limit block, thereby reducing the possibility that the test fixture exceeds the elastic deformation range after being subjected to pressure; and after conducting a vehicle road test, based on the actual strain received by the vehicle and the mapping relationship between the pressure preset by the test fixture and the strain, the actual dynamic load received by the test fixture under different characteristic roads is calculated to reflect the dynamic load that the entire vehicle frame may actually be subjected to during the movement of the vehicle, thereby improving the range accuracy of vehicle strength enhancement, and solving the problems existing in the prior art of measuring the deformation of a certain point on the vehicle frame, which is prone to distortion of detection data and is difficult to directly reflect the actual load received by the vehicle frame as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 This is a schematic diagram of the structure of the test fixture attached to the vehicle frame in this application;

[0037] Figure 2 This is a schematic diagram of the structure of the test tooling in this application;

[0038] Figure 3 This is a schematic diagram of the structure when the data acquisition device is connected to the test fixture in this application;

[0039] Figure 4 A structural diagram of the test fixture and the buffer limit block fixed on the buffer limit block strain test device in this application;

[0040] In the figure: 1. test fixture; 11. test base plate; 111. fixed support foot; 12. strain measurement space; 2. buffer limit block; 3. measurement strain gauge; 31. data acquisition instrument; 4. calibration platform; 41. contour pressure head; 5. vehicle frame; 6. vehicle axle; 61. leaf spring. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] The embodiment of the present application provides a method for testing the dynamic load of a vehicle frame, which can solve the problem in the prior art that when measuring the deformation of a certain point on the vehicle frame 5, the detection data is easily distorted and it is difficult to directly reflect the actual load on the vehicle frame 5 as a whole.

[0043] Reference Figure 1 The present application discloses a method for testing the dynamic load of an automobile frame, comprising the following steps:

[0044] S1: Installing the test fixture 1 equipped with the buffer limit block 2 onto the vehicle frame 5;

[0045] Reference Figure 1 The installation area of ​​the test fixture 1 is specifically set on the side wall opposite to the vehicle frame 5 and the vehicle axle 6. The test fixture 1 specifically includes a test base plate 11. The buffer limit block 2 is detachably mounted on the test base plate 11 by bolts, and the test base plate 11 is detachably mounted on the vehicle frame 5 by bolts. The test fixture 1 can provide a measuring surface for the pressure measurement of the buffer limit block 2, reducing the possibility that the test fixture 1 exceeds the elastic deformation range after being subjected to pressure.

[0046] In the subsequent vehicle road test, when the vehicle passes through a bumpy road section, the vehicle axle 6 is subjected to real-time stress and firstly absorbs the shock through the leaf spring 61 at the bottom. The leaf spring 61, with its good elastic deformation ability and recovery, can quickly absorb and disperse the impact force it receives when the vehicle encounters bumps, and then make the vehicle axle 6 bounce upward. This process not only reduces the vibration directly transmitted to the vehicle frame 5, but also improves the smoothness of the vehicle passing through the road and the riding experience of the user. However, relying solely on the shock-absorbing effect of the leaf spring 61 is not enough to completely eliminate all vibrations. If the upward displacement of the axle is not effectively restricted, it may cause unnecessary collision with the vehicle frame 5, resulting in structural damage or increased noise.

[0047] Therefore, by installing the buffer limit block 2 at the bottom of the vehicle frame 5 and opposite to the surface of the vehicle axle 6, when the vehicle axle 6 bounces up to a certain height, a soft and effective barrier can be provided for the vehicle axle 6 to prevent further uncontrolled displacement of the vehicle axle 6. Furthermore, before installing the buffer limit block 2 to the surface of the test fixture 1, that is, in the pre-production stage, the surface of the buffer limit block 2 is specifically set to an arc shape that matches the surface of the vehicle axle 6, so that the contact between the buffer limit block 2 and the vehicle axle 6 changes from surface contact to line contact, so as to contact the surface of the vehicle axle 6 more smoothly, which not only optimizes the contact area between the buffer limit block 2 and the vehicle axle 6, improves the uniformity during collision contact, but also ensures good adaptability under different stress states, thereby extending the service life of the buffer limit block 2 and the vehicle axle 6, while improving the reliability and durability of the overall vehicle.

[0048] In the early stage of design, since the strains that the vehicle frame 5 may be subjected to are unknown, these strains may come from a variety of factors, including but not limited to vibrations caused by unevenness under different characteristic roads, twisting forces during sharp turns, uneven pressure distribution under heavy loads, and possible collision impacts, etc. Since the specific magnitude and direction of these strains are difficult to accurately estimate in the early stage of design, in order to ensure the overall structural safety and reliability of the vehicle, the material of the test base plate 11 can be selected from a rigid metal material with higher strength than the material of the vehicle frame 5. High-strength rigid metal materials can more effectively resist external impacts and internal strains, thereby providing an additional safety barrier for the vehicle frame 5 when the buffer limit block 2 is accidentally hit by the vehicle axle 6, which can disperse and absorb the impact energy and reduce the impact force directly transmitted to the vehicle frame 5, so as to protect the vehicle frame 5 when the buffer limit block 2 is hit by the vehicle axle 6 during the subsequent vehicle road test, and reduce the possibility of the vehicle frame 5 being impacted and broken due to excessive strain. Furthermore, by using a stronger material to manufacture the test base plate 11, it is possible to simulate or even exceed the most extreme operating conditions that the vehicle may encounter during actual driving to a certain extent, thereby discovering potential structural weaknesses or design defects in advance, and helping engineers to adjust and optimize the manufacturing materials of the vehicle frame 5 during the design stage, thereby avoiding costly modifications at a later stage.

[0049] Reference Figure 2 and Figure 3 The cross-sectional dimension of the test base plate 11 is larger than the cross-sectional dimension of the buffer limit block 2, so that the buffer limit block 2 can be firmly installed on the surface of the test base plate 11, reducing the possibility of shaking or misalignment of the buffer limit block 2, and when the buffer limit block 2 is installed on the surface of the test base plate 11, a spacing is reserved between the buffer limit block 2 and the edge of the test base plate 11 in the length direction to form a strain measurement space 12, and a measuring strain gauge 3 is affixed to the strain measurement space 12. The measuring strain gauge 3 is a high-precision and high-sensitivity sensor that can record in real time the tiny real-time strains generated by the test base plate 11 during vehicle driving. In subsequent vehicle road tests, the actual strain received by the vehicle to be tested on roads with different characteristics is recorded by measuring the strain gauge 3. The tester can analyze key indicators such as the vehicle's driving stability under different road conditions, the performance of the suspension system, and the fatigue degree of the vehicle structure based on the data of these actual strain quantities.

[0050] More specifically, the measuring strain gauge 3 needs to be flat and firmly attached to the surface of the test base plate 11 to ensure that the measuring strain gauge 3 can accurately capture the strain signal. Sufficient installation space helps to reduce the possibility of the measuring strain gauge 3 being squeezed or stretched during the installation process, thereby improving its measurement accuracy. Therefore, the width of the strain measurement space 12 needs to be greater than or equal to 10 mm to provide sufficient installation space for the measuring strain gauge 3. Furthermore, when attaching the measuring strain gauge 3, the measuring strain gauge 3 can be attached in the middle of the strain measurement space 12 on the upper and lower bottom surfaces of the test base plate 11, thereby increasing the recording position of the measuring strain gauge 3, thereby obtaining more strain data. Multi-point measurement helps to more comprehensively understand the strain conditions of the test base plate 11 at different positions and directions, improve the accuracy and reliability of the measurement, and thus improve the measurement accuracy of the actual strain amount.

[0051] Fixed legs 111 are also provided at both ends of the length direction of the test base plate 11. The test base plate 11 is fixed to the vehicle frame 5 through the fixed legs 111. The fixed legs 111 can provide a stable fulcrum for the test base plate 11. When the buffer limit block 2 is impacted and squeezed by the vehicle axle 6, the middle part of the test base plate 11 will be slightly deformed due to the impact. The setting of the fixed legs 111 can provide a fixed fulcrum for the test base plate 11 on the one hand, and on the other hand, it can form a certain gap between the test base plate 11 and the surface of the vehicle frame 5, reducing the possibility of the test base plate 11 contacting the surface of the vehicle frame 5 when bending, so that the test base plate 11 will not be subject to the counter-support force from the vehicle frame 5 when impacted, and can more accurately measure and analyze the strain of the test base plate when impacted, thereby improving the test accuracy.

[0052] S2: Conducting a vehicle road test to obtain the actual strain of the test fixture 1;

[0053] S3: Based on the actual strain amount and the mapping relationship between the pressure preset by the test fixture 1 and the strain amount, the actual stress under the actual strain amount is obtained.

[0054] The present application discloses a method for testing the dynamic load of an automobile frame, which further includes obtaining a mapping relationship between a preset pressure of a test fixture 1 and a strain amount, which specifically includes:

[0055] S301: Installing the buffer limit block 2 onto the surface of the test fixture 1;

[0056] S302: applying different pressures toward the buffer limit block 2 to obtain the strain amount of the surface of the test tool 1 under different pressures;

[0057] More specifically, refer to Figure 3 and Figure 4, a strain test device can be used to apply pressure toward the buffer limit block 2, and a data acquisition instrument 31 can be used to obtain the strain on the surface of the test fixture 1 under different pressures. The strain test device includes a calibration platform 4, on which a contouring indenter 41 is provided, and the moving end surface of the contouring indenter 41 is adapted to the curvature of the outer surface of the buffer limit block 2, so that when the moving end surface of the contouring indenter 41 contacts the outer surface of the buffer limit block 2 and continuously applies pressure toward the outer surface of the buffer limit block 2, the pressure can be evenly and accurately applied to the limit block, thereby avoiding measurement errors caused by uneven pressure distribution.

[0058] Before applying different pressures to the buffer limit block 2, the test fixture 1 with the buffer limit block 2 installed is first placed on the calibration station of the calibration platform 4. After the test base plate 11 is stably placed on the surface of the calibration platform 4, the data acquisition instrument 31 and the measuring strain gauge 3 on the test base plate 11 are connected. At the same time, the data acquisition instrument 31 and the profiling pressure head 41 are turned on, so that the profiling pressure head 41 moves downward to pressurize the surface of the buffer limit block 2. When the buffer limit block 2 is subjected to different pressures, it will cause the test base plate 11 to undergo slight deformation. The real-time stress actually generated by the test base plate 11 when the buffer limit block 2 is subjected to different pressures can be obtained by measuring the strain gauge 3 and the data acquisition instrument 31.

[0059] S303: Based on the different applied pressures and the corresponding strains, a mapping relationship between the preset pressure and the strain of the test fixture 1 is obtained.

[0060] Based on the real-time stress of the test base plate 11 when the buffer limit block 2 is subjected to different pressures, a stress curve of the pressure and strain of the test base plate 11 can be produced, that is, a mapping relationship between the pressure preset by the test fixture 1 and the strain.

[0061] After the vehicle road test, the different actual strain values ​​recorded on each characteristic road surface on the measuring strain gauge 3 are brought into the mapping relationship between the preset pressure and the strain value of the test fixture 1, so as to obtain the actual dynamic load on the test fixture 1 under the actual strain value, thereby reflecting the dynamic load that the entire vehicle frame 5 may actually be subjected to during the movement of the vehicle, thereby improving the range accuracy of the vehicle strength enhancement, and solving the problems existing in the prior art of measuring the deformation of a certain point on the vehicle frame 5, which is prone to distortion of the detection data and is difficult to directly reflect the actual load on the vehicle frame 5 as a whole.

[0062] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0063] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0064] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for testing dynamic load of an automobile frame, characterized in that: It includes: Installing the test fixture (1) equipped with the buffer limit block (2) on the vehicle frame (5); Conducting a vehicle road test to obtain the actual strain of the test fixture (1); Based on the actual strain amount and the mapping relationship between the preset pressure of the test fixture (1) and the strain amount, the actual dynamic load under the actual strain amount is obtained.

2. A vehicle frame dynamic load testing method according to claim 1, characterized in that: The automobile frame dynamic load testing method further comprises: obtaining a mapping relationship between a preset pressure of the testing tool (1) and a strain amount; Obtaining a mapping relationship between the preset pressure of the test fixture (1) and the strain, which specifically includes: Installing the buffer limit block (2) onto the surface of the testing tool (1); Applying different pressures toward the buffer limit block (2) to obtain the strain amount of the surface of the test tool (1) under different pressures; Based on the different applied pressures and the corresponding strain amounts, a mapping relationship between the preset pressure of the test fixture (1) and the strain amount is obtained.

3. A vehicle frame dynamic load testing method according to claim 2, characterized in that: Before the buffer limit block (2) is mounted on the surface of the test fixture (1), the method further comprises: The buffer limit block (2) is manufactured based on the surface shape of the vehicle axle (6) to be tested, so that the buffer limit block (2) and the surface curved surface of the vehicle axle (6) to be tested are consistent.

4. A vehicle frame dynamic load testing method according to claim 2, characterized in that: The testing tool (1) comprises: A test base plate (11), wherein the cross-sectional dimensions of the test base plate (11) are greater than the cross-sectional dimensions of the buffer limit block (2); when the buffer limit block (2) is mounted on the test base plate (11), a strain measurement space (12) is formed between the buffer limit block (2) and an edge of the test base plate (11) in a length direction; and a measuring strain gauge (3) is arranged on the strain measurement space (12).

5. A vehicle frame dynamic load testing method according to claim 4, characterized in that: Applying pressure toward the buffer limit block (2) specifically includes: The test base plate (11) to which the buffer limit block (2) is fixed is mounted on a strain test device, and the strain test device is turned on to apply pressure toward the buffer limit block (2); The strain testing device specifically comprises: A calibration platform (4), wherein a profiling pressure head (41) is arranged on the calibration platform (4), and a movable end of the profiling pressure head (41) is adapted to the outer surface of the buffer limit block (2).

6. A vehicle frame dynamic load testing method according to claim 5, characterized in that: Obtaining the strain amount of the surface of the test fixture (1) under different pressures, which specifically includes: Connecting a data acquisition instrument (31) to the measuring strain gauge (3); The data acquisition instrument (31) and the contouring pressure head (41) are simultaneously turned on to obtain the strain amount of the surface of the test base plate (11) under different pressures when the strain amount testing device applies different pressures toward the buffer limit block (2); Based on the real-time stress of the test base plate (11) when it is subjected to different pressures, a stress curve of pressure and strain of the test base plate (11) is produced.

7. A vehicle frame dynamic load testing method according to claim 4, characterized in that: The width of the strain measurement space (12) is greater than or equal to 10 mm.

8. The method for testing the dynamic load of an automobile frame according to claim 4, characterized in that: Fixed legs (111) are provided on both sides of the test base plate (11) in the length direction.

9. The method for testing the dynamic load of an automobile frame according to claim 4, characterized in that: The test base plate (11) is made of a rigid metal material, and the strength of the test base plate is higher than the strength of the vehicle frame (5).

10. The method for testing the dynamic load of an automobile frame according to claim 1, characterized in that: The test base plate is installed on the vehicle frame (5), which specifically includes: The test base plate (11) is detachably connected to the vehicle frame (5) via bolts.

Images