Vehicle frame static rigidity testing method and vehicle frame static rigidity testing device

Abstract

The invention provides a method and a device for testing the static rigidity of a vehicle frame, and relates to the field of mechanical property detection of mechanical structures. The method comprises the following steps: determining at least two excitation response points on a frame; determining a plurality of target excitation points based on the at least two excitation response points; exciting the plurality of target excitation points to obtain excitation response data of each excitation response point in the at least two excitation response points; obtaining a target matrix based on the excitation response data of each excitation response point; wherein the target matrix is used for representing an association relationship between the excitation response data of each excitation response point; and determining the static stiffness of the frame based on the target matrix. Based on the scheme, the accuracy of the static rigidity test result of the frame can be improved.

Description

Technical Field

[0001] This application relates to the field of mechanical performance testing of mechanical structures, and more specifically, to a method and apparatus for testing the static stiffness of a vehicle frame in the field of mechanical performance testing of mechanical structures. Background Technology

[0002] The static stiffness of a frame (e.g., bending stiffness and torsional stiffness) is used to represent the frame’s ability to resist bending and torsional deformation when a load is applied to the frame, and can be used to measure the frame’s permissible deformation.

[0003] In related technologies, during the static stiffness analysis of a vehicle frame, test points at specific locations can be selected, and the static stiffness of the frame can be obtained by performing static stiffness analysis on the vibration signal at those test points. However, the accuracy of the static stiffness test results obtained by this method is poor.

[0004] Therefore, improving the accuracy of static stiffness test results for vehicle frames is an urgent problem to be solved. Summary of the Invention

[0005] This application provides a method and apparatus for testing the static stiffness of a vehicle frame, which can improve the accuracy of the static stiffness test results.

[0006] Firstly, a method for testing the static stiffness of a vehicle frame is provided, the method comprising:

[0007] At least two excitation response points are determined on the frame; several target excitation points are determined based on the at least two excitation response points; the several target excitation points are excited to obtain the excitation response data of each of the at least two excitation response points; a target matrix is ​​obtained based on the excitation response data of each excitation response point; the target matrix is ​​used to represent the correlation between the excitation response data of each excitation response point; the static stiffness of the frame is determined based on the target matrix.

[0008] In this embodiment, when several target excitation points are excited, excitation response data corresponding to at least two excitation response points are obtained. This means the target matrix obtained from the excitation response data of at least two excitation response points is influenced by those two points. Therefore, the target matrix, compared to single-point excitation response data, better reflects the influence of at least two excitation response points on each other's excitation response data. This avoids the problem that the static stiffness calculated from the excitation response data of a single excitation point can only represent a local static stiffness. Thus, when several target excitation points are excited, a target matrix reflecting the overall excitation response of the frame can be obtained. The overall static stiffness of the frame can be calculated using this target matrix, reducing the deviation between the static stiffness test results and the actual static stiffness, and improving the accuracy of the frame static stiffness test results.

[0009] In conjunction with the first aspect, in some implementations of the first aspect, the target matrix is ​​obtained based on the stimulus response data at each stimulus response point, including:

[0010] Based on the excitation response data at each excitation response point, determine the modal parameter data at each excitation response point; based on the modal parameter data at each excitation response point, determine the compliance function at each excitation response point; based on the compliance function at each excitation response point, obtain the target matrix.

[0011] In this embodiment, since the target matrix is ​​obtained based on the compliance function of each excitation response point, the target matrix is ​​affected by at least two excitation response points. Therefore, the static stiffness of the frame calculated by this target matrix can represent the overall static stiffness of the frame when several target excitation points are excited, thereby reducing the deviation between the static stiffness test results and the actual static stiffness of the frame and improving the accuracy of the static stiffness test results of the frame.

[0012] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the target matrix is ​​obtained based on the compliance function of each excitation response point, including:

[0013] Determine whether the compliance function of each excitation response point contains a preset target point; where the vibration frequency of the preset target point is 0; if the compliance function of each excitation response point contains the preset target point, determine the vibration amplitude corresponding to the preset target point in the compliance function of each excitation response point; combine the vibration amplitudes of each excitation response point to obtain the target matrix.

[0014] In this embodiment, since the compliance function of each excitation response point includes a preset target point with a vibration frequency of 0, and the preset target point with a vibration frequency of 0 can indicate that the static stiffness and dynamic stiffness of the frame are the same, after determining that the compliance function of each excitation response point includes a target point with a vibration frequency of 0, the vibration amplitude corresponding to the preset target point included in the compliance function of each excitation response point is then determined. The target matrix is ​​obtained by combining the vibration amplitudes of each excitation response point. This ensures that the obtained target matrix is ​​used to calculate the static stiffness of the frame, rather than the dynamic stiffness of the frame, thereby further improving the accuracy of the static stiffness test results of the frame.

[0015] In conjunction with the first aspect and the above implementation methods, in some implementations of the first aspect, the method further includes:

[0016] Obtain the applied load at each excitation response point; combine the applied loads at each excitation response point to obtain the target load matrix; the above-mentioned combination of the vibration amplitudes at each excitation response point to obtain the target matrix includes: combining the vibration amplitudes at each excitation response point to obtain the target compliance matrix; multiplying the target compliance matrix with the target load matrix to generate the target matrix.

[0017] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the determination of the static stiffness of the frame based on the target matrix includes:

[0018] Based on the target matrix, the bending displacement of the frame is obtained; by dividing the applied load at each excitation response point by the bending displacement, the bending stiffness in the static stiffness is obtained; or, based on the target matrix, the torsional angle of the frame is obtained; the torsional stiffness in the static stiffness is obtained by performing a reciprocal operation on the torsional angle.

[0019] In this embodiment of the application, when the target matrix is ​​affected by at least two excitation response points, the bending displacement obtained by the target matrix is ​​also affected by at least two excitation response points. That is, the bending displacement is obtained under the mutual influence of at least two excitation response points, which can represent the bending displacement of the whole frame when the target excitation point is excited. This allows the bending stiffness calculated by the bending displacement to represent the bending stiffness of the whole frame, thereby reducing the deviation between the bending stiffness test results and the actual bending stiffness of the frame and improving the accuracy of the bending stiffness test results of the frame.

[0020] Alternatively, when the target matrix is ​​affected by at least two excitation response points, the torsional angle obtained through the target matrix will also be affected by at least two excitation response points. That is, the torsional angle is obtained under the mutual influence of at least two excitation response points, which can represent the torsional angle of the entire frame when it is excited at the target excitation point. This allows the torsional stiffness calculated through the torsional angle to represent the torsional stiffness of the entire frame, thereby reducing the deviation between the torsional stiffness test results and the actual torsional stiffness of the frame and improving the accuracy of the torsional stiffness test results of the frame.

[0021] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the above-mentioned stimulation of several target stimulus points and acquisition of stimulus response data of each stimulus response point among at least two stimulus response points include:

[0022] Multiple stimulations are applied to several target stimulus points to obtain the first stimulus response data for each stimulus response point in each stimulation. The average of multiple first stimulus response data is then applied to obtain the stimulus response data.

[0023] In this embodiment of the application, by averaging multiple excitation response data when several target excitation points are excited multiple times, the accuracy of the excitation response data can be improved, thereby further improving the accuracy of the static stiffness test results of the frame based on the more accurate excitation response data.

[0024] In conjunction with the first aspect and the above implementation methods, in some implementations of the first aspect, the method further includes:

[0025] Based on the modal parameter data, the rigid body modes of the frame are obtained; based on the rigid body modes, it is determined whether the frame is in a free boundary state; the above-mentioned determination of the compliance function of each excitation response point based on the modal parameter data of each excitation response point includes: when it is determined that the frame is in a free boundary state, the compliance function of each excitation response point is determined based on the modal parameter data of each excitation response point.

[0026] In this embodiment, the rigid body modes of the frame are obtained through modal parameter data, and the frame is judged to be in a free boundary state through rigid body. Only when the frame is in a free boundary state is the compliance function of each excitation response point determined based on the modal parameter data of each excitation response point. This can minimize the influence of the spring structure on the compliance function of each excitation response point, making the compliance function of each excitation response point more accurate. Thus, based on the more accurate compliance function of each excitation response point, the accuracy of the static stiffness test results of the frame is further improved.

[0027] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the determination of whether the frame is in a free boundary state based on rigid body modes includes:

[0028] If the ratio of the rigid body mode to the preset elastic mode is less than or equal to the preset ratio, the frame is determined to be in a free boundary state; where the preset elastic mode is the first-order elastic body mode of the frame; if the ratio is greater than the preset ratio, the frame is determined not to be in a free boundary state.

[0029] In conjunction with the first aspect and the above implementation methods, in some implementations of the first aspect, the method further includes:

[0030] If the frame is not in a free boundary state, the frame can be adjusted to a free boundary state by adjusting the first elastic structure of the suspension frame or the second elastic structure of the support frame.

[0031] In this embodiment, since the elastic structure has a significant impact on the compliance function of each excitation response point when the frame is not in a free boundary state, adjusting the first elastic structure of the suspension frame or the second elastic structure of the support frame to adjust the frame to a free boundary state can minimize the impact of the elastic structure on the compliance function of each excitation response point, making the compliance function of each excitation response point more accurate. This, in turn, further improves the accuracy of the static stiffness test results of the frame based on the more accurate compliance function of each excitation response point.

[0032] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the determination of several target incentive points based on at least two incentive response points includes:

[0033] Acquire the position data of each of the at least two excitation response points; based on the position data of each excitation response point, determine the position data of each of the several excitation points; determine the target points on the chassis corresponding to the position data of each excitation point as several target excitation points; wherein, the position data of each excitation response point and the position data of the corresponding excitation points are opposite to each other. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the static stiffness test of the vehicle frame provided in an embodiment of this application.

[0035] Figure 2 This is a schematic flowchart of a method for testing the static stiffness of a vehicle frame provided in an embodiment of this application.

[0036] Figure 3 This is a schematic diagram of a static equilibrium model provided in an embodiment of this application.

[0037] Figure 4 This is a flowchart illustrating another method for testing the static stiffness of a vehicle frame provided in an embodiment of this application. Detailed Implementation

[0038] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0039] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0040] For example, the static stiffness of a frame (e.g., bending stiffness and torsional stiffness) is used to represent the frame's ability to resist bending and torsional deformation when loads are applied to it, and can be used to measure the permissible deformation of the frame. Most frames on the market use a monocoque frame structure, and the frame needs to withstand different types of loads during use, such as bending loads, torsional loads, and impact loads.

[0041] Applying bending, torsional, and impact loads to the chassis can cause deformation in areas such as door frames, window frames, or the hood. This can lead to problems like doors jamming, windows failing to operate properly, and engine compartment leaks, affecting the chassis's normal operation. Therefore, the chassis design process must consider the overall rigidity of the chassis and the deformation of key components to ensure that the static rigidity meets the rigidity requirements during use.

[0042] In related technologies, when performing static stiffness testing on a vehicle frame, a special tooling fixture is required to fix the frame, and a hydraulic cylinder or pneumatic cylinder is used to apply load to the test points of the frame. Simultaneously, a displacement sensor mounted on the frame collects the displacement of the test points after the load is applied. The static stiffness of the frame is calculated using formula (1):

[0043] Static stiffness = Applied load ÷ Displacement (1)

[0044] However, during the static stiffness testing of the vehicle frame, the tooling fixtures can affect the test results, leading to significant deviations and reducing the accuracy of the results, thus impacting the repeatability of the static stiffness test. Furthermore, the free boundary conditions set for the vehicle frame are difficult to reproduce in Computer-Aided Engineering (CAE), resulting in poor comparability between the static stiffness test results and the finite element analysis (FEA) simulation results. Therefore, to address the influence of tooling fixtures on the static stiffness test, this application proposes the following... Figure 1 The structure shown is for static stiffness testing.

[0045] Figure 1 This is a schematic diagram of the static stiffness test of the vehicle frame provided in an embodiment of this application.

[0046] For example, such as Figure 1 As shown, Figure 1 It includes a frame 110, an elastic structure 120, a hammer impact point 130, a modal force hammer 140, a vibration sensor 150, and electronic equipment 160.

[0047] The frame 110 is placed horizontally.

[0048] The elastic structure 120 is mounted on the frame 110, keeping the frame 110 in a balanced state, also known as a "free boundary state." The elastic structure 120 includes, but is not limited to, elastic ropes, springs, and gas springs. Furthermore, the elastic structure 120 can be as follows: Figure 1 The installation is shown at the four corners of the frame 110, but it can also be installed according to actual testing requirements. This application embodiment does not limit this.

[0049] Hammering point 130 is used to indicate the test point in the frame 110.

[0050] The modal force hammer 140 is used to strike the hammer impact point 130, that is, to excite the hammer impact point 130.

[0051] Vibration sensor 150 is used to collect vibration signals at impact point 130 when modal force hammer 140 strikes impact point 130. Vibration sensor 150 is mounted on the frame 110. Vibration sensor 150 includes, but is not limited to, displacement sensors.

[0052] The first signal input port of the electronic device 160 is electrically connected to the signal output port of the modal hammer 140, and is used to receive the force applied by the modal hammer 140 when it strikes the hammer impact point 130, i.e., to apply a load. The second signal input port of the electronic device 160 is electrically connected to the signal output port of the vibration sensor 150, and is used to receive the vibration signal collected by the vibration sensor. The first signal input port and the second signal input port may be the same or different.

[0053] Furthermore, the electronic device 160 is also equipped with a data processing unit 161 for simulating and analyzing the received applied loads and vibration signals to calculate the static stiffness of the frame 110. The data processing unit 161 includes, but is not limited to, LMSTestlab and LMS Virtual.Lab.

[0054] For example, the frame 110 can be adjusted to a free boundary state by means of the elastic structure 120, without the need for special tooling fixtures, thus avoiding the influence of tooling fixtures on static stiffness test.

[0055] Furthermore, after the frame 110 is in a free boundary state, the modal hammer 140 can be used to strike the impact point 130, and the vibration signal of the frame 110 when the modal hammer 140 strikes the impact point 130 can be collected by the vibration sensor 150. There is no need to use additional hammering equipment, which improves the convenience of hammering test points in static stiffness testing. The vibration signal and the hammering force of the modal hammer 140 (i.e., the applied load) are transmitted to the electronic device 120. The data processing unit 161 configured in the electronic device 120 performs simulation analysis on the vibration signal and the applied load to calculate the static stiffness of the frame 110. This makes the free boundary condition easy to reproduce in CAE and makes the static stiffness test and FEA results more comparable.

[0056] However, the static stiffness of the frame obtained by simulating the vibration signal and applied load corresponding to the impact point 130 is too limited and cannot reflect the effect of the excitation of the impact point 13 on the overall static stiffness of the frame. This results in a deviation in the static stiffness test results of the frame and poor accuracy.

[0057] To address the issue of deviations in the static stiffness test results of vehicle frames, this application proposes a method and apparatus for testing the static stiffness of vehicle frames.

[0058] The following is combined with Figures 2 to 3 The test method for the static stiffness of the vehicle frame provided in the embodiments of this application is described in detail.

[0059] Figure 2 This is a schematic flowchart illustrating a method for testing the static stiffness of a vehicle frame according to an embodiment of this application. This method can be performed by... Figure 1The electronic device 160 in the middle performs the operation.

[0060] For example, such as Figure 2 As shown, the method 200 includes the following implementation process:

[0061] S210, determine at least two excitation response points on the chassis.

[0062] For example, when conducting static stiffness tests on the frame, multiple test points can be identified on the frame, such as at least two excitation response points.

[0063] Optionally, in order to collect vibration signals from each of the multiple excitation response points, a corresponding signal acquisition device (e.g., a vibration sensor) can be installed at the location of each excitation response point on the chassis. That is, the installation location of the signal acquisition device is the same as the location of the excitation response point.

[0064] Optionally, during static stiffness testing, the frame can be placed horizontally, and multiple elastic structures 120 (e.g., spring ropes) can be installed on the frame to place the frame 110 in a free boundary state. Figure 1 As shown, the frame is suspended by four spring ropes, placing it in a free-boundary state. Alternatively, the frame can be supported by an elastic structure 120 (e.g., a gas spring), also placing it in a free-boundary state; this embodiment does not limit the scope of the invention.

[0065] S220, determine several target excitation points based on at least two excitation response points.

[0066] For example, after determining multiple excitation response points on the frame, it is necessary to determine the excitation point (i.e., target excitation point) corresponding to each excitation response point on the frame. At least one target excitation point (which can be referred to as "several target excitation points") can be determined based on at least two excitation response points.

[0067] Optionally, the above method of determining several target excitation points based on at least two excitation response points includes: acquiring the position data of each excitation response point among at least two excitation response points; determining the position data of each excitation point among several excitation points based on the position data of each excitation response point; and determining the target points corresponding to the position data of each excitation point on the vehicle frame as several target excitation points; wherein the position data of each excitation response point and the position data of the corresponding excitation point are opposite to each other.

[0068] For example, after determining multiple excitation response points on the frame, the position data of each excitation response point can be acquired. Since vibration sensors need to be installed at these excitation response points, to ensure excitation of the frame, position data on the opposite side of the excitation response point's position data can be acquired. The position on the frame corresponding to this opposite side's position data (which can be called the "target point") is then determined as the position of the excitation point corresponding to the excitation response point. That is, the excitation response point and its corresponding excitation point are not on the same side, but on opposite sides; and the excitation response point is determined on the frame first, and then the corresponding excitation point is determined on the frame based on that excitation response point.

[0069] Figure 3 This is a schematic diagram of a static equilibrium model provided in an embodiment of this application.

[0070] For example, such as Figure 3 As shown, Figure 3 (a) in the figure represents the static equilibrium model of bending stiffness in static stiffness. Figure 3 (b) in the figure represents the static equilibrium model of torsional stiffness in static stiffness.

[0071] like Figure 3 As shown in (a), the static equilibrium model of bending stiffness includes six excitation response points, which are divided into four constraint points and two loading points. Excitation response points 1 and 2 are loading points (i.e., points where loads are applied), while excitation response points 3, 4, 5, and 6 are constraint points (i.e., points that constrain the frame and generate reaction forces). For ease of distinction, excitation response points 1 and 2 will be referred to as loading points 1 and 2, respectively; and excitation response points 3, 4, 5, and 6 will be referred to as constraint points 3, 4, 5, and 6, respectively. Furthermore, for ease of calculation, loading points 1 and 2, constraint points 3 and 4, and constraint points 5 and 6 are symmetrical. It should be understood that the selection of the location and number of excitation response points needs to be based on the actual testing requirements of bending stiffness, and this embodiment does not limit this selection.

[0072] refer to Figure 3 From (a) in the diagram, we can obtain that the distance between loading point 1 and constraint point 5 is b, and the distance between constraint point 3 and constraint point 5 is a. Based on moment balance, when the applied loads at loading points 1 and 2 are both -1, constraint points 3, 4, 5, and 6 will generate corresponding reaction forces. The reaction forces at constraint points 3 and 4 are a / b, and the reaction forces at constraint points 5 and 6 are (ab) / b. For ease of description, these reaction forces are also referred to as the "applied loads" at each constraint point.

[0073] like Figure 3 As shown in (b), the static equilibrium model of torsional stiffness includes four excitation response points, which are divided into two constraint points and two loading points. Excitation response points 7 and 8 are loading points (i.e., points where loads are applied), and excitation response points 9 and 10 are constraint points (i.e., points that constrain the frame and generate reaction forces). For ease of distinction, excitation response points 7 and 8 will be referred to as loading points 7 and 8, respectively; and excitation response points 9 and 10 will be referred to as constraint points 9 and 10, respectively. Furthermore, for ease of calculation, loading points 7 and 8, and constraint points 9 and 10 are symmetrical. It should be understood that the selection of the location and number of excitation response points needs to be based on the actual testing requirements of torsional stiffness, and this embodiment does not limit this selection.

[0074] refer to Figure 3 From (b) in the diagram, we can obtain that the distance between loading point 7 and loading point 8 is c, and the distance between constraint point 9 and constraint point 10 is d. Based on moment balance, we can obtain that when the applied load at loading point 7 is -1000 / c, constraint point 9 will generate a corresponding reaction force of 1000 / d; and when the applied load at loading point 8 is 1000 / c, constraint point 10 will generate a corresponding reaction force of -1000 / d. For ease of description, this reaction force is also referred to as the "applied load" at each constraint point.

[0075] Optionally, Figure 3 As shown in (a), loading point 1, loading point 2, constraint point 3, constraint point 4, constraint point 5, and constraint point 6 are all excitation response points determined on the frame, and it is necessary to determine the excitation point corresponding to each excitation response point. For example, the position data of loading point 1 on the frame can be obtained, and the position data 1 on the opposite side of this position data can be obtained. The position corresponding to position data 1 on the frame can be determined as excitation point 1, and loading point 1, loading point 2, constraint point 3, constraint point 4, constraint point 5, and constraint point 6 are all excitation response points corresponding to excitation point 1. Similarly, the excitation points 2, 3, 4, 5, and 6 corresponding to loading point 2, constraint point 3, constraint point 4, constraint point 5, and constraint point 6, as well as the excitation response points corresponding to excitation points 2, 3, 4, 5, and 6, can be obtained, i.e., loading point 1, loading point 2, constraint point 3, constraint point 4, constraint point 5, and constraint point 6, which will not be elaborated further here.

[0076] Optionally, Figure 3As shown in (b), loading points 7 and 8, and constraint points 9 and 10 are all excitation response points determined on the chassis, and it is necessary to determine the excitation point corresponding to each excitation response point. For example, the position data of loading point 7 on the chassis can be obtained, and the position data 7 on the opposite side of this position data can be obtained. The position corresponding to position data 7 on the chassis can be determined as the excitation point, and loading points 7, 8, 9, and 10 are all excitation response points corresponding to excitation point 7. Similarly, the excitation points 8, 9, and 10 corresponding to loading points 8, 9, and 10, and the excitation response points corresponding to excitation points 8, 9, and 10 can be obtained, i.e., loading points 7, 8, 9, and 10, respectively, which will not be elaborated further here.

[0077] S230, stimulate several target stimulus points and obtain stimulus response data of each stimulus response point in at least two stimulus response points.

[0078] For example, a simulated force hammer can be used to excite several target excitation points perpendicular to the ground, and a vibration sensor can be used to collect the vibration signals of each of the at least two excitation response points corresponding to each of the several target excitation points, i.e., excitation response data.

[0079] For example, when testing the bending stiffness of a vehicle frame, a simulated force hammer can be used to excite excitation points 1 and 2. Simultaneously, vibration sensors corresponding to loading points 1, 2, constraint points 3, 4, 5, and 6 are used to collect the excitation response data at each excitation point when excited at excitation points 1 and 2.

[0080] For example, when testing the torsional stiffness of the chassis, a simulated force hammer can be used to excite excitation points 7 and 8. Simultaneously, vibration sensors corresponding to loading points 7, 8, constraint points 9, and 10 are used to collect excitation response data at each excitation point when excited at excitation points 7 and 8.

[0081] In one possible implementation, the above-mentioned stimulation of several target stimulus points and acquisition of stimulus response data of each stimulus response point among at least two stimulus response points includes: stimulating several target stimulus points multiple times, acquiring the first stimulus response data corresponding to each stimulus response point in each of the multiple stimulations; and averaging the multiple first stimulus response data to obtain the stimulus response data.

[0082] For example, to reduce the experimental error in static stiffness testing, a simulated force hammer can be used to excite each of several target excitation points multiple times, for example, five times. A vibration sensor is then used to collect the vibration signal corresponding to each excitation response point during each excitation (which can be called "first excitation response data"). The average value of multiple first excitation response data corresponding to the same excitation response point is then calculated to obtain the average response data corresponding to that excitation response point, and this average response data is used as the excitation response data corresponding to the excitation response point.

[0083] For example, when testing the bending stiffness of the chassis, a simulated hammer can be used to excite point 2 five times, while a load of -1 is applied to both loading points 1 and 2. Simultaneously, vibration sensors corresponding to loading points 1, 2, constraint points 3, 4, 5, and 6 collect the excitation response data for each of the five excitations. Assuming the excitation response data for constraint point 3 is 1, 1.1, 1.1, 1, 1, then the average of these five excitation response data for constraint point 3 is calculated to obtain an average response data of 1.04. This 1.04 is then used as the excitation response data for constraint point 3 for subsequent calculations of the chassis bending stiffness.

[0084] For example, when testing the torsional stiffness of the chassis, a simulated hammer can be used to excite point 8 five times, while a load of -1000 / c is applied to loading point 7 and a load of 1000 / c is applied to loading point 8. Simultaneously, vibration sensors corresponding to loading points 7, 8, constraint points 9, and constraint point 10 collect the excitation response data for each of the five excitations. Assuming the excitation response data for constraint point 9 during each of the five excitations are 3, 3.1, 3.05, 2.95, and 3, the average response data for constraint point 9 can be averaged to obtain an average response data of 3.02. This 3.02 is then used as the excitation response data for constraint point 9 for subsequent calculations of the chassis torsional stiffness.

[0085] Optionally, when the simulated hammer excites each excitation point 5 times, it should be ensured that the position and excitation force of each excitation are the same, or within the allowable error range.

[0086] In this embodiment of the application, by averaging multiple excitation response data when several target excitation points are excited multiple times, the accuracy of the excitation response data can be improved, thereby further improving the accuracy of the static stiffness test results of the frame based on the more accurate excitation response data.

[0087] S240, based on the stimulus response data of each stimulus response point, obtain the target matrix.

[0088] The target matrix can represent the correlation between the excitation response data of each excitation response point, and this target matrix can be used to calculate the static stiffness of the frame.

[0089] For example, the excitation response data corresponding to each excitation response point collected is input into the LMS Testlab software for data fitting to obtain a matrix (which can be called the "target matrix") that can be used to calculate the static stiffness of the frame. Since the target matrix is ​​not calculated from single-point excitation response data, but from the interaction between the excitation response points corresponding to several target excitation points, it is more able to reflect the influence of at least two excitation response points on each other's excitation response data compared to single-point excitation response data.

[0090] In one possible implementation, obtaining the target matrix based on the stimulus response data of each stimulus response point includes: determining the modal parameter data of each stimulus response point based on the stimulus response data of each stimulus response point; determining the compliance function of each stimulus response point based on the modal parameter data of each stimulus response point; and obtaining the target matrix based on the compliance function of each stimulus response point.

[0091] For example, the collected excitation response data corresponding to each excitation response point is input into the modal analysis module in the LMS Testlab software for modal analysis to obtain the modal parameter data corresponding to each excitation response point.

[0092] Furthermore, data fitting processing is performed on the modal parameter data corresponding to each excitation response point to obtain the modal composite curve corresponding to each of the multiple modal parameter data. Then, the modal composite curve is integrated multiple times (e.g., twice) to obtain the compliance function after integration processing. The multiple compliance functions corresponding to each excitation response point are used to form the target matrix.

[0093] In this embodiment, since the target matrix is ​​obtained based on the compliance function of each excitation response point, the target matrix is ​​affected by at least two excitation response points. Therefore, the static stiffness of the frame calculated by this target matrix can represent the overall static stiffness of the frame when several target excitation points are excited, thereby reducing the deviation between the static stiffness test results and the actual static stiffness of the frame and improving the accuracy of the static stiffness test results of the frame.

[0094] Optionally, the rigid body modes of the frame are obtained based on the modal parameter data; based on the rigid body modes, it is determined whether the frame is in a free boundary state; the above determination of the compliance function of each excitation response point based on the modal parameter data of each excitation response point includes: when it is determined that the frame is in a free boundary state, the compliance function of each excitation response point is determined based on the modal parameter data of each excitation response point.

[0095] For example, after analyzing the modal parameter data of each excitation response point, the modal analysis module can perform rigid body modal fitting on the modal parameter data, and compare the magnitude of the rigid body mode with the preset elastic mode to determine whether the frame is in a free boundary state. And when the frame is in a free boundary state, the compliance function of each excitation response point is determined based on the modal parameter data of each excitation response point.

[0096] In this embodiment, the rigid body modes of the frame are obtained through modal parameter data, and the frame is judged to be in a free boundary state through rigid body. Only when the frame is in a free boundary state is the compliance function of each excitation response point determined based on the modal parameter data of each excitation response point. This can minimize the influence of the spring structure on the compliance function of each excitation response point, making the compliance function of each excitation response point more accurate. Thus, based on the more accurate compliance function of each excitation response point, the accuracy of the static stiffness test results of the frame is further improved.

[0097] Optionally, the above determination of whether the frame is in a free boundary state based on rigid body modes includes: if the ratio of the rigid body mode to the preset elastic mode is less than or equal to the preset ratio, the frame is determined to be in a free boundary state; wherein, the preset elastic mode is the first-order elastic body mode of the frame; if the ratio is greater than the preset ratio, the frame is determined not to be in a free boundary state.

[0098] Among them, the preset elastic mode can represent the first-order elastic body mode of the frame.

[0099] For example, if the ratio of the rigid body mode fitted based on modal parameter data to the first-order elastic body mode is less than or equal to a preset ratio of 1 / 10, it can be determined that the frame is currently in a free boundary state. It should be understood that the magnitude of the preset ratio is related to the testing requirements of static stiffness, and this application embodiment does not limit it.

[0100] For example, if the ratio of the rigid body mode to the first-order elastic body mode is 1 / 12, which is less than the preset ratio of 1 / 10, then it can be determined that the frame is currently in a free boundary state.

[0101] Alternatively, if the ratio of the rigid body mode fitted based on the modal parameter data to the first-order elastic body mode is greater than the preset ratio of 1 / 10, it indicates that the frame is not currently in a free boundary state.

[0102] For example, if the ratio of the rigid body mode to the first-order elastic body mode is 3 / 10, which is greater than the preset ratio of 1 / 10, it indicates that the frame is not currently in a free boundary state.

[0103] Furthermore, since the elastic structure has a significant impact on the compliance function at each excitation response point when the frame is not in a free boundary state (i.e., non-free boundary state), to avoid this impact, if the frame is not in a free boundary state, the first elastic structure of the suspension frame or the second elastic structure of the support frame can be adjusted to bring the frame to a free boundary state.

[0104] The first elastic structure, such as a spring cable, is used to suspend the frame; the second elastic structure, such as a gas spring, is used to support the frame. That is, the adjustment functions of the first spring structure and the second spring structure on the frame are different.

[0105] For example, to adjust the frame from a non-free boundary state to a free boundary state, the elastic cable can be adjusted to change the suspension state of the frame, thereby adjusting the frame from a non-free boundary state to a free boundary state. Alternatively, the gas spring can be adjusted to change the support state of the frame, thereby adjusting the frame from a non-free boundary state to a free boundary state.

[0106] Optionally, to ensure the accuracy of determining whether the frame is in a free boundary state, multiple elastic body modes can be identified, such as 47th or 48th elastic body modes. The order of the elastic body modes is related to the actual test, and this embodiment does not limit this.

[0107] Furthermore, when the frame is adjusted from a non-free boundary state to a free boundary state, the target excitation point is re-excited, and the corresponding compliance function is obtained by fitting the modal parameter data corresponding to each excitation response point.

[0108] In this embodiment, since the elastic structure has a significant impact on the compliance function of each excitation response point when the frame is not in a free boundary state, adjusting the first elastic structure of the suspension frame or the second elastic structure of the support frame to adjust the frame to a free boundary state can minimize the impact of the elastic structure on the compliance function of each excitation response point, making the compliance function of each excitation response point more accurate. This, in turn, further improves the accuracy of the static stiffness test results of the frame based on the more accurate compliance function of each excitation response point.

[0109] In one possible implementation, obtaining the target matrix based on the compliance function of each excitation response point includes: determining whether the compliance function of each excitation response point contains a preset target point; wherein the vibration frequency of the preset target point is 0; if the compliance function of each excitation response point contains the preset target point, determining the vibration amplitude corresponding to the preset target point in the compliance function of each excitation response point; and combining the vibration amplitudes of each excitation response point to obtain the target matrix.

[0110] For example, when stimulating any target excitation point in a static equilibrium model, multiple compliance functions corresponding to each excitation response point can be obtained. Since the dynamic stiffness of the frame is equal to the static stiffness when the compliance function includes a frequency point with a vibration frequency of 0 Hz (which can be called the "preset target point"), the static stiffness of the frame can be indirectly obtained through the vibration amplitude corresponding to the 0 Hz frequency point. Therefore, when the compliance function corresponding to multiple excitation response points includes a frequency point with a vibration frequency of 0 Hz, the vibration amplitude corresponding to the 0 Hz frequency point can be obtained, and the vibration amplitudes of each excitation response point at the 0 Hz frequency point can be combined to obtain the target matrix.

[0111] It should be understood that the compliance function can include not only the frequency point of 0Hz, but also the frequency points of 1Hz, 3Hz, etc. Each frequency point has its own corresponding vibration amplitude. That is, the compliance function can be represented as a set of multiple frequency points and the vibration amplitudes corresponding to each of the multiple frequency points.

[0112] Optionally, if the compliance function does not include a frequency point with a vibration frequency of 0Hz, it means that only the dynamic stiffness of the frame can be obtained, but not the static stiffness. To obtain the static stiffness of the frame, the target excitation point needs to be re-excited, and the corresponding compliance function needs to be fitted based on the modal parameter data corresponding to each excitation response point. It is then necessary to determine again whether the refitted compliance function includes a 0Hz frequency point. If the refitted compliance function includes a 0Hz frequency point, the vibration amplitude corresponding to the 0Hz frequency point can be obtained, and the vibration amplitudes of each excitation response point at the 0Hz frequency point can be combined to obtain the target matrix. Alternatively, if the refitted compliance function still does not include a 0Hz frequency point, the above process is repeated until the refitted compliance function includes a 0Hz frequency point.

[0113] In this embodiment, since the compliance function of each excitation response point includes a preset target point with a vibration frequency of 0, and the preset target point with a vibration frequency of 0 can indicate that the static stiffness and dynamic stiffness of the frame are the same, after determining that the compliance function of each excitation response point includes a target point with a vibration frequency of 0, the vibration amplitude corresponding to the preset target point included in the compliance function of each excitation response point is then determined. The target matrix is ​​obtained by combining the vibration amplitudes of each excitation response point. This ensures that the obtained target matrix is ​​used to calculate the static stiffness of the frame, rather than the dynamic stiffness of the frame, thereby further improving the accuracy of the static stiffness test results of the frame.

[0114] Optionally, in the process of generating the target matrix, it is also necessary to obtain the applied loads at each excitation response point. Specifically, the applied loads at each excitation response point are combined to obtain the target load matrix; the above-mentioned combination of the vibration amplitudes at each excitation response point to obtain the target matrix includes: combining the vibration amplitudes at each excitation response point to obtain the target compliance matrix; and multiplying the target compliance matrix with the target load matrix to generate the target matrix.

[0115] For example, when testing the bending stiffness of a vehicle frame, if an excitation point is applied, there will be six excitation response points. For instance, when excitation point 1 is applied, loading point 1, loading point 2, constraint point 3, constraint point 4, constraint point 5, and constraint point 6 are all excitation response points corresponding to excitation point 1. Since these six excitation response points influence each other, each excitation response point will have six corresponding compliance functions collected, resulting in 36 compliance functions. The vibration amplitude corresponding to the 0Hz frequency point included in each of the 36 compliance functions is obtained, and the 36 vibration amplitudes are combined to obtain the compliance amplitude table for bending stiffness. This can be explained in detail in Table 1.

[0116] Table 1

[0117] Motivation Point 1 Motivation Point 2 Motivation Point 3 Motivation Point 4 Motivation Point 5 Motivation Point 6 Load point 1 <![CDATA[H 11 ]]> <![CDATA[H 12 ]]> <![CDATA[H 13 ]]> <![CDATA[H 14 ]]> <![CDATA[H 15 ]]> <![CDATA[H 16 <!-- 10 -->]]> Loading point 2 <![CDATA[H 21 ]]> <![CDATA[H 22 ]]> <![CDATA[H 23 ]]> <![CDATA[H 24 ]]> <![CDATA[H 25 ]]> <![CDATA[H 26 ]]> Constraint point 3 <![CDATA[H 31 ]]> <![CDATA[H 32 ]]> <![CDATA[H 33 ]]> <![CDATA[H 34 ]]> <![CDATA[H 35 ]]> <![CDATA[H 36 ]]> Constraint point 4 <![CDATA[H 41 ]]> <![CDATA[H 42 ]]> <![CDATA[H 43 ]]> <![CDATA[H 44 ]]> <![CDATA[H 45 ]]> <![CDATA[H 46 ]]> Constraint point 5 <![CDATA[H 51 ]]> <![CDATA[H 52 ]]> <![CDATA[H 53 ]]> <![CDATA[H 54 ]]> <![CDATA[H 55 ]]> <![CDATA[H 56 ]]> Constraint point 6 <![CDATA[H 61 ]]> <![CDATA[H 62 ]]> <![CDATA[H 63 ]]> <![CDATA[H 64 ]]> <![CDATA[H 65 ]]> <![CDATA[H 66 ]]>

[0118] In Table 1, the horizontal columns represent the locations of the excitation points, and the vertical columns represent the locations of the excitation response points. For example, when the excitation point is excitation point 1, loading point 1, loading point 2, constraint point 3, constraint point 4, constraint point 5, and constraint point 6 are all the locations of the corresponding excitation response points. It should be understood that the locations of the excitation response points corresponding to excitation points 2, 3, 4, 5, and 6 can be referenced from the excitation response point corresponding to excitation point 1, and will not be elaborated further here.

[0119] For example, taking excitation point 1 and loading point 2 as an example, H 21 In the table, subscript "1" indicates the location of excitation point 1, and subscript "2" indicates the location of the corresponding excitation response point, loading point 2. Additionally, other vibration amplitude values ​​in Table 1 are referenced from "H". 21 ", which will not be elaborated upon here.

[0120] For example, the various flexibility amplitudes in the flexibility amplitude table of bending stiffness can be combined to obtain the flexibility amplitude matrix of bending stiffness (which can be called the "target flexibility matrix"). This is illustrated by formula (2):

[0121]

[0122] Furthermore, based on the compliance amplitude matrix of the bending stiffness, the applied loads at each excitation response point can be obtained, and the applied loads at each excitation response point can be combined into an applied load matrix (which can be called the "target load matrix") as shown in formula (3). This is explained using formula (3):

[0123]

[0124] For example, multiplying the compliance magnitude matrix of the bending stiffness with the target load matrix yields the target matrix as shown in formula (4). Formula (4) will be used to illustrate this:

[0125]

[0126] Where x1 represents the displacement of loading point 1, x2 represents the displacement of loading point 2, and so on, which will not be elaborated here.

[0127] For example, when testing the torsional stiffness of a vehicle frame, if an excitation point is applied, there will be four excitation response points. For instance, when excitation point 7 is applied, loading point 7, loading point 8, constraint point 9, and constraint point 10 are all excitation response points corresponding to excitation point 7. Since the four excitation response points influence each other, four corresponding compliance functions will be collected for each excitation response point. These four compliance functions for each of the four excitation response points result in 16 compliance functions. The vibration amplitude corresponding to the 0Hz frequency point included in each of the 16 compliance functions is obtained. These 16 vibration amplitudes are combined to obtain the compliance amplitude table for torsional stiffness. This can be further explained in Table 2.

[0128] Table 2

[0129] Motivation Point 7 Motivation Point 8 Motivation Point 9 Incentive Point 10 Loading point 7 <![CDATA[H 77 ]]> <![CDATA[H 78 ]]> <![CDATA[H 79 ]]> <![CDATA[H 7,10 ]]> Loading point 8 <![CDATA[H 87 ]]> <![CDATA[H 88 ]]> <![CDATA[H 89 ]]> <![CDATA[H 8,10 ]]> Constraint point 9 <![CDATA[H 97 ]]> <![CDATA[H 98 ]]> <![CDATA[H 99 ]]> <![CDATA[H 9,10 ]]> Constraint point 10 <![CDATA[H 10,7 ]]> <![CDATA[H 10,8 ]]> <![CDATA[H 10,9 ]]> <![CDATA[H 10,10 ]]>

[0130] In Table 2, the horizontal columns represent the locations of the excitation points, and the vertical columns represent the locations of the excitation response points. For example, when the excitation point is excitation point 7, loading point 7, loading point 8, constraint point 9, and constraint point 10 are all the locations of the corresponding excitation response points. It should be understood that the locations of the excitation response points corresponding to loading point 7, loading point 8, constraint point 9, and constraint point 10 can be referenced from the excitation response point corresponding to excitation point 7, and will not be elaborated further here.

[0131] For example, taking excitation point 7 and loading point 8 as an example, H 87 The subscript "7" indicates the location of excitation point 7, and the subscript "8" indicates the location of the corresponding excitation response point, loading point 8. Other vibration amplitude values ​​in Table 2 are referenced from "H". 87 ", which will not be elaborated upon here.

[0132] For example, the various flexibility amplitudes in the torsional stiffness flexibility amplitude table can be combined to obtain the torsional stiffness flexibility amplitude matrix (also called the "target flexibility matrix"). This is illustrated by formula (5):

[0133]

[0134] Furthermore, based on the compliance amplitude matrix of torsional stiffness, the applied loads at each excitation response point can be obtained, and the applied loads at each excitation response point can be combined into an applied load matrix (which can be called the "target load matrix") as shown in formula (6). This is explained using formula (6):

[0135]

[0136] For example, multiplying the compliance magnitude matrix of torsional stiffness by the target load matrix yields the target matrix as shown in formula (6). The target matrix is ​​then obtained. This is illustrated by formula (7):

[0137]

[0138] Where x7 represents the displacement of loading point 7, x8 represents the displacement of loading point 8, and so on, which will not be elaborated here.

[0139] S250, based on the target matrix, determines the static stiffness of the chassis.

[0140] For example, after obtaining the target matrix through the above steps, the static stiffness of the frame can be calculated using Excel or Matlab.

[0141] In such Figure 2 In method 200, when several target excitation points are excited, excitation response data corresponding to at least two excitation response points are acquired. This means the target matrix obtained from the excitation response data of at least two excitation response points is influenced by those two points. Therefore, the target matrix, compared to single-point excitation response data, better reflects the influence of at least two excitation response points on each other's excitation response data. This avoids the problem that the static stiffness calculated from the excitation response data of a single excitation point can only represent a local static stiffness. Thus, when several target excitation points are excited, a target matrix reflecting the overall excitation response of the frame can be obtained. The overall static stiffness of the frame can be calculated using this target matrix, reducing the deviation between the static stiffness test results and the actual static stiffness, and improving the accuracy of the frame static stiffness test results.

[0142] Optionally, the above determination of the static stiffness of the frame based on the target matrix includes: obtaining the bending displacement of the frame based on the target matrix; and obtaining the bending stiffness in the static stiffness by dividing the applied load at each excitation response point by the bending displacement.

[0143] For example, formula (4) can be calculated using Excel or Matlab to obtain the displacement of each excitation response point. The displacement of each excitation response point is then input into formula (8) to calculate the bending displacement of the target excitation point relative to the excitation response point, which can be denoted as "x". bend ".

[0144]

[0145] Furthermore, after calculating x bend After that, you can obtain Figure 3 The applied loads corresponding to the points shown in (a) are, for example, -1 for both loading points 1 and 2. Then, the sum of the applied loads at loading points 1 and 2 is calculated, and this sum is compared with x. bend Divide by the value to calculate the bending stiffness, which can be denoted as "k". bend This can be explained using formula (9):

[0146]

[0147] Where the subscript "-11" indicates that "-1" corresponds to the applied load at loading point 1; and the subscript "-12" indicates that "-1" corresponds to the applied load at loading point 2. When the units of a and b are mm, and the applied load force is N, k... bend The unit is N / mm.

[0148] In this embodiment of the application, when the target matrix is ​​affected by at least two excitation response points, the bending displacement obtained by the target matrix is ​​also affected by at least two excitation response points. That is, the bending displacement is obtained under the mutual influence of at least two excitation response points, which can represent the bending displacement of the whole frame when the target excitation point is excited. This allows the bending stiffness calculated by the bending displacement to represent the bending stiffness of the whole frame, thereby reducing the deviation between the bending stiffness test results and the actual bending stiffness of the frame and improving the accuracy of the bending stiffness test results of the frame.

[0149] Optionally, the above-mentioned determination of the static stiffness of the frame based on the target matrix includes: obtaining the torsional angle of the frame based on the target matrix; and performing a reciprocal operation on the torsional angle to obtain the torsional stiffness in the static stiffness.

[0150] For example, formula (7) can be calculated using Excel or Matlab to obtain the displacement of each excitation response point. The displacement of each excitation response point is then input into formula (10) to calculate the torsion angle of the target excitation point relative to the excitation response point, which can be denoted as "θ". tortion ".

[0151]

[0152] Here, ATAN represents the arctangent function, used to calculate the arctangent value.

[0153] Furthermore, after calculating θ tortion Then, the θ can be... tortion To calculate torsional stiffness, derivative operations are performed, and the result can be denoted as "k". tortion This can be explained using formula (11):

[0154]

[0155] Where the units for a and b are mm, and θ tortion The unit is rad, and k is the force applied when the applied load is N. tortion The unit is Nm / rad.

[0156] In this embodiment of the application, when the target matrix is ​​affected by at least two excitation response points, the torsional angle obtained by the target matrix is ​​also affected by at least two excitation response points. That is, the torsional angle is obtained under the mutual influence of at least two excitation response points, which can represent the torsional angle of the whole frame when it is excited at the target excitation point. This allows the torsional stiffness calculated by the torsional angle to represent the torsional stiffness of the whole frame, thereby reducing the deviation between the torsional stiffness test results and the actual torsional stiffness of the frame and improving the accuracy of the torsional stiffness test results of the frame.

[0157] Figure 4 This is a flowchart illustrating another method for testing the static stiffness of a vehicle frame provided in an embodiment of this application.

[0158] For example, such as Figure 4 As shown, the method 400 includes the following implementation process:

[0159] S401, at least two excitation response points are determined on the chassis; and the positions on the chassis corresponding to the position data opposite to the position data of each of the at least two excitation response points are determined as several target excitation points.

[0160] For example, when testing the bending stiffness or torsional stiffness of the frame, the frame can be suspended by spring ropes or supported by gas springs to keep the frame horizontal, and the free boundary state of the frame can be adjusted by adjusting the spring ropes and gas springs; and multiple excitation response points can be determined on the frame.

[0161] Furthermore, the position data of each excitation response point is obtained, and the position data that is opposite to the position data of the excitation response point is obtained. The position of the opposite position data on the frame is determined as the position of the excitation point corresponding to the excitation response point.

[0162] Optionally, the excitation response point selected when using tooling fixtures to fix the frame can be used as the excitation response point determined in this application. The selection of the excitation response point is obtained through static stiffness testing experience, and this application embodiment does not limit this.

[0163] S402, apply multiple excitations to several target excitation points, and obtain the current excitation response data of each excitation point in at least two excitation response points in each of the multiple excitations.

[0164] For example, a simulated force hammer can be used to excite several target excitation points perpendicular to the ground, and a vibration sensor can be used to collect the current excitation response data of each of the at least two excitation response points corresponding to each target excitation point during each excitation.

[0165] For example, if stimulus point 1 is stimulated 5 times, the stimulus response data corresponding to each of the five stimuli can be collected, namely, the stimulus response data for each stimulus.

[0166] S403, average the multiple current stimulus response data to obtain the average response data corresponding to each stimulus response point.

[0167] For example, the average of five stimulus response data points corresponding to the same stimulus response point can be processed to obtain the average response data corresponding to the same stimulus response point.

[0168] S404, based on the mean response data of each excitation response point, determine the modal parameter data of each excitation response point.

[0169] For example, the mean response data of each excitation response point can be input into the modal analysis module of the LMS Testlab software for modal analysis to obtain the modal parameter data corresponding to each excitation response point.

[0170] S405, based on the modal parameter data of each excitation response point, obtains the rigid body modes of the frame.

[0171] For example, after analyzing the modal parameter data of each excitation response point, the modal analysis module can perform rigid body modal fitting on the modal parameter data to obtain the corresponding rigid body modes.

[0172] S406, Determine if the chassis is in a free-bound state. If yes, proceed to S407; otherwise, proceed to S408.

[0173] For example, after fitting the rigid body modes of the frame, it can be determined whether the frame is in a free boundary state based on the rigid body modes.

[0174] Optionally, the ratio of the rigid body mode fitted based on the modal parameter data to the first-order elastic body mode can be obtained. If the ratio is less than or equal to a preset ratio of 1 / 10, it can be determined that the frame is currently in a free boundary state.

[0175] Alternatively, if the ratio is greater than the preset ratio of 1 / 10, it indicates that the frame is not currently in a free boundary state.

[0176] S407, based on the modal parameter data of each excitation response point, determine the compliance function of each excitation response point.

[0177] For example, if the frame is found to be in a free boundary state through S406, then the modal parameter data corresponding to each excitation response point can be subjected to data fitting processing to obtain the modal composite curves corresponding to each of the multiple modal parameter data. Then, the modal composite curves are subjected to two integral processing to obtain the compliance function after integral processing.

[0178] The S408 adjusts the frame from a non-free boundary state to a free boundary state by adjusting the elastic structure.

[0179] For example, if it is determined through S406 that the frame is not in a free boundary state, the suspension state of the frame can be adjusted by adjusting the elastic rope to change the frame from a non-free boundary state to a free boundary state. Alternatively, the support state of the frame can be adjusted by adjusting the gas spring to change the frame from a non-free boundary state to a free boundary state; then, the target excitation point can be re-excited to obtain the modal parameter data corresponding to the frame in the free boundary state.

[0180] S409, determine whether the compliance function contains a frequency point where the vibration frequency is 0. If yes, proceed to S410; otherwise, proceed to S402.

[0181] For example, when fitting the compliance function of each excitation response point, it is determined whether the compliance function includes a frequency point with a vibration frequency of 0 Hz.

[0182] S410, determine the vibration amplitude corresponding to the frequency point with a vibration frequency of 0 in the compliance function corresponding to each excitation response point.

[0183] For example, if the compliance function includes a frequency point with a vibration frequency of 0Hz, obtained through S409, the vibration amplitude corresponding to the 0Hz frequency point in the compliance function of each excitation response point can be obtained.

[0184] For example, if the compliance function obtained through S409 does not include a frequency point with a vibration frequency of 0Hz, S402 can be executed again to excite several target excitation points multiple times, obtaining the excitation response data corresponding to each excitation response point in each of the multiple excitations from at least two excitation response points. That is, the target excitation points are re-excited, and the corresponding compliance function is obtained by fitting the modal parameter data corresponding to each excitation response point, and it is determined again whether the refitted compliance function includes a 0Hz frequency point. If the refitted compliance function includes a 0Hz frequency point, the vibration amplitude corresponding to the 0Hz frequency point can be obtained, and the vibration amplitudes of each excitation response point at the 0Hz frequency point can be combined to obtain the target matrix.

[0185] Alternatively, if the refitted compliance function still does not include the 0Hz frequency point, then repeat step S402 until the refitted compliance function includes the 0Hz frequency point.

[0186] S411, combine the vibration amplitudes of each excitation response point to obtain the compliance matrix; and, obtain the applied loads of each excitation response point and combine the applied loads of each excitation response point to obtain the load matrix; then multiply the compliance matrix and the load matrix to generate the target matrix.

[0187] For example, the vibration amplitudes corresponding to each excitation response point can be combined to obtain a compliance matrix as shown in formula (2) or formula (5); and the applied loads at each excitation response point can be obtained and the applied loads at each excitation response point can be combined to form a load matrix as shown in formula (3) or formula (6).

[0188] Furthermore, by multiplying the compliance matrix and the load matrix, the target matrix can be obtained as shown in formula (4) or formula (7).

[0189] S412, based on the target matrix, the bending displacement of the frame is obtained; the bending stiffness is obtained by dividing the applied load at each excitation response point by the bending displacement.

[0190] For example, when calculating bending stiffness, the displacement of each excitation response point can be calculated using formula (4), and the displacement of each excitation response point can be input into formula (8) to calculate the bending displacement of the target excitation point relative to the excitation response point, i.e., x. bend ; and calculate the sum of the applied loads at loading point 1 and loading point 2, and then combine this sum with x bend Divide to calculate the bending stiffness, i.e., k. bend .

[0191] Reference Figure 3 In (a), loading point 1 and loading point 2 are the points where the load is applied. Therefore, the sum of the applied load at loading point 1 and the applied load at loading point 2 can be calculated, which is -2. Then, -2 is divided by x. bend , to obtain k bend .

[0192] S413, based on the target matrix, obtain the torsional angle of the frame; perform a reciprocal operation on the torsional angle to obtain the torsional stiffness.

[0193] For example, when calculating torsional stiffness, the displacement of each excitation response point can be calculated using formula (7), and the displacement of each excitation response point can be input into formula (10) to calculate the torsional angle of the target excitation point relative to the excitation response point, i.e., θ. tortion ; after that, regarding θ tortion Perform derivative operations to calculate the torsional stiffness, i.e., k. tortion .

[0194] It should be noted that when conducting the bending stiffness test of the frame, S412 is performed; when conducting the torsional stiffness test of the frame, S413 is performed.

[0195] It should be noted that, Figure 4 All steps are in Figure 2 The corresponding embodiments are described in detail, and will not be repeated here.

[0196] It should be understood that the above examples are provided to help those skilled in the art understand the embodiments of this application, and are not intended to limit the embodiments of this application to the specific values ​​or scenarios illustrated. Those skilled in the art can obviously make various equivalent modifications or changes based on the above examples, and such modifications or changes also fall within the scope of the embodiments of this application.

[0197] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0198] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0199] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for testing the static stiffness of a vehicle frame, characterized in that, The method includes: Identify at least two excitation response points on the chassis; Based on the at least two stimulus response points, determine several target stimulus points; The plurality of target stimulus points are stimulated, and the stimulus response data of each of the at least two stimulus response points is obtained; Based on the stimulus response data of each stimulus response point, a target matrix is ​​obtained; wherein, the target matrix is ​​used to represent the correlation between the stimulus response data of each stimulus response point; Based on the target matrix, the static stiffness of the vehicle frame is determined.

2. The method according to claim 1, characterized in that, The target matrix is ​​obtained based on the stimulus response data of each stimulus response point, including: Based on the excitation response data of each excitation response point, determine the modal parameter data of each excitation response point; Based on the modal parameter data of each excitation response point, the compliance function of each excitation response point is determined; The target matrix is ​​obtained based on the compliance function of each excitation response point.

3. The method according to claim 2, characterized in that, The target matrix is ​​obtained based on the compliance function of each excitation response point, including: Determine whether the compliance function of each excitation response point contains a preset target point; wherein the vibration frequency of the preset target point is 0. If the compliance function of each excitation response point contains the preset target point, determine the vibration amplitude corresponding to the preset target point in the compliance function of each excitation response point; The vibration amplitudes of each excitation response point are combined to obtain the target matrix.

4. The method according to claim 3, characterized in that, The method further includes: Obtain the applied load at each of the excitation response points; The applied loads at each of the excitation response points are combined to obtain the target load matrix; The step of combining the vibration amplitudes of the various excitation response points to obtain the target matrix includes: The vibration amplitudes of each excitation response point are combined to obtain the target compliance matrix; The target matrix is ​​generated by multiplying the target compliance matrix by the target load matrix.

5. The method according to any one of claims 1 to 4, characterized in that, Determining the static stiffness of the vehicle frame based on the target matrix includes: Based on the target matrix, the bending displacement of the vehicle frame is obtained; the bending stiffness in the static stiffness is obtained by dividing the applied load at each excitation response point by the bending displacement; or... Based on the target matrix, the torsional angle of the frame is obtained; the torsional stiffness in the static stiffness is obtained by performing a reciprocal operation on the torsional angle.

6. The method according to any one of claims 1 to 4, characterized in that, The step of stimulating the plurality of target stimulus points and obtaining stimulus response data for each of the at least two stimulus response points includes: The plurality of target stimulus points are stimulated multiple times, and the first stimulus response data corresponding to each stimulus response point in each of the multiple stimulus events is obtained; The stimulus response data is obtained by averaging multiple sets of the first stimulus response data.

7. The method according to any one of claims 2 to 4, characterized in that, The method further includes: Based on the modal parameter data, the rigid body modes of the vehicle frame are obtained; Based on the rigid body modes, determine whether the vehicle frame is in a free boundary state; The determination of the compliance function for each excitation response point based on the modal parameter data of each excitation response point includes: When the frame is determined to be in the free boundary state, the compliance function of each excitation response point is determined based on the modal parameter data of each excitation response point.

8. The method according to claim 7, characterized in that, Determining whether the vehicle frame is in a free boundary state based on the rigid body modes includes: If the ratio of the rigid body mode to the preset elastic mode is less than or equal to the preset ratio, the frame is determined to be in a free boundary state; wherein, the preset elastic mode is the first-order elastic body mode of the frame; If the ratio is greater than the preset ratio, it is determined that the frame is not in the free boundary state.

9. The method according to claim 8, characterized in that, The method further includes: If the frame is not in the free boundary state, the frame can be adjusted to the free boundary state by adjusting the first elastic structure suspending the frame or adjusting the second elastic structure supporting the frame.

10. The method according to any one of claims 1 to 4, characterized in that, The determination of several target stimulus points based on the at least two stimulus response points includes: Obtain the position data of each of the at least two stimulus response points; Based on the location data of each of the stimulus response points, determine the location data of each of the stimulus points among the plurality of stimulus points; The position data of each excitation point are used to determine the target points on the vehicle frame corresponding to the target excitation points; The location data of each stimulus response point is opposite to the location data of the corresponding stimulus point.

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