A method for compiling load spectrum for rapid durability test of front axle

Abstract

The present invention discloses a method for compiling a load spectrum for a front axle durability rapid test. The present invention takes into account that the load spectra collected from the same part of a vehicle under the same test field road and test specifications are similar. Based on the existing front axle load spectrum data of heavy vehicles, combined with finite element analysis theory and methods, load spectrum standardization research, inter-wheel load difference analysis, multi-axis damage assessment, multi-axis load dimensionality reduction processing, etc., a method for compiling a load spectrum for a front axle durability rapid test is provided. The test load spectrum can be quickly obtained based on the front axle load data of existing vehicle models, which can be used for reliability verification of the front axle, shorten the research and development cycle, and save costs. At the same time, after dimensionality reduction processing, the complexity of the bench test can be simplified, the configuration requirements for the test bench can be reduced, and the feasibility of the front axle durability evaluation can be further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile durability test, and in particular relates to a method for compiling a load spectrum for a front axle durability rapid test. Background Art

[0002] The collection and compilation of the load spectrum in the test field is the basis of the front axle durability bench test, which usually requires a series of work such as sensor layout, road spectrum signal collection, and signal processing. The cycle is long, consuming a lot of manpower and financial resources, and it is impossible to verify the reliability of the front axle in the early stage of design. To this end, the present invention proposes a method for compiling a front axle durability rapid test load spectrum based on the existing heavy-duty vehicle front axle load data. Summary of the invention

[0003] The purpose of the present invention is to provide a method for compiling a load spectrum for a front axle durability rapid test to solve the problems existing in the above-mentioned prior art.

[0004] To achieve the above object, the present invention provides a method for compiling a load spectrum for a front axle durability rapid test, comprising:

[0005] Apply unit loads in different directions to the front axle of the heavy vehicle, take this process as the load history of the front axle, and analyze the failure position and damage contribution value of the front axle in the load history;

[0006] Acquire peak-valley values ​​of the front axle in the load history, and acquire a relative dynamic load coefficient based on the peak-valley values;

[0007] Constructing a front axle load history of a light vehicle based on the relative dynamic load coefficient;

[0008] Performing time domain characteristic analysis of left and right side loads and wheel difference analysis on the front axle load history of the light vehicle to obtain the load history of the side with a larger damage contribution value;

[0009] Based on the load history of the side with a larger damage contribution value, load coupling damage assessment in Fx and Fz directions is performed on the two-dimensional plane where the front axle of the light vehicle is located, and damage contribution values ​​generated in different directions are obtained and dimensionality reduction processing is performed;

[0010] Based on the Fx and Fz load history of the front axle of the light vehicle, a front axle durability rapid test load spectrum is compiled.

[0011] Optionally, in the process of analyzing the failure location and damage contribution value of the front axle in the load history, the different directions include three directions of X, Y, and Z, and only the failure location and damage contribution value in the X direction and the Z direction are analyzed.

[0012] Optionally, before obtaining the relative dynamic load coefficient based on the peak-to-valley value, the method further includes: normalizing the load history of the front axle.

[0013] Optionally, the process of obtaining the peak and valley values ​​of the front axle in the load history also includes obtaining a peak and valley value-frequency distribution diagram based on the peak and valley values; the process of obtaining the relative dynamic load coefficient load history based on the relative dynamic load coefficient also includes: obtaining a relative dynamic load coefficient-frequency distribution diagram based on the relative dynamic load coefficient obtained.

[0014] Optionally, the process of analyzing the time domain characteristics of the left and right side loads and the wheel-to-wheel difference analysis of the front axle load history of the light vehicle includes:

[0015] Performing time domain characteristic analysis of left and right side loads on the front axle load history of the light vehicle, and comparing the time domain synchronization of the left and right side loads of the front axle;

[0016] By compiling an acceleration spectrum for the side with a larger damage contribution value, normalization of the loads on the left and right sides of the front axle is achieved.

[0017] Optionally, the process of performing load coupling damage assessment in the Fx-Fz direction on the two-dimensional plane where the front axle of the light vehicle is located, obtaining damage contribution values ​​generated in different directions and performing dimensionality reduction processing includes:

[0018] Taking the two-dimensional plane where the front axle of the light vehicle is located as a reference, a direction is determined every 10°, and a total of 19 directions are determined;

[0019] Calculate the damage contribution value generated by the load history in each direction, perform multi-axis damage assessment, and obtain the assessment results;

[0020] A dimensionality reduction process is performed on the multi-axial load based on the evaluation result.

[0021] Optionally, the process of compiling a front axle durability rapid test load spectrum based on the Fx and Fz direction load history of the front axle of the light vehicle includes:

[0022] Based on the rain flow counting method, the load history in Fx and Fz directions is counted to obtain the number of load cycles under each stress range;

[0023] Based on the linear cumulative damage formula, the damage corresponding to each level of load is calculated, and the five-level load spectrum is edited;

[0024] Based on the damage equivalence principle, each level of load is transferred to the highest level;

[0025] Obtain the durability bench load spectrum of the front axle of a light vehicle.

[0026] Optionally, the process of obtaining a light vehicle front axle durability bench load spectrum includes:

[0027] The load amplitude after each level of load is transferred to the highest level is obtained, the load amplitude is increased by 10%, and multiplied by the vertical force when the light vehicle is fully loaded at rest, to obtain the durability bench load spectrum of the light vehicle front axle.

[0028] The technical effects of the present invention are:

[0029] The present invention takes into account the similarity of the load spectra collected from the same part of the vehicle under the same test field road and test specifications, and combines the finite element analysis theory and method, load spectrum standardization research, multi-axis damage assessment, multi-axis load dimensionality reduction processing, wheel load difference analysis and other technologies to analyze, screen and process the load data of the front axle of the existing heavy-duty vehicle, and can quickly compile a 2.4T light front axle durability bench test load spectrum. The compiled load spectrum can be used to verify the reliability of the front axle in the early stage of design, shorten the test cycle, and reduce costs. At the same time, after the dimensionality reduction process, the complexity of the bench test can be simplified, the configuration requirements of the test bench can be reduced, and the feasibility of the front axle durability evaluation can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 A flow chart of a method for compiling a load spectrum for a front axle durability rapid test in Embodiment 2 of the present invention;

[0032] Figure 2 The front axle load history of some heavy-duty vehicles in the second embodiment of the present invention;

[0033] Figure 3 The load peak-valley value-frequency distribution diagram of the 8.5T and 4.5T vehicle models in the second embodiment of the present invention;

[0034] Figure 4 The relative dynamic load coefficient-frequency distribution diagram of the 8.5T and 4.5T vehicle models in the second embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the load history of the relative dynamic load coefficient of the front axle of a 2.4T vehicle model in the second embodiment of the present invention;

[0036] Figure 6 It is a time domain characteristic diagram of the left and right side loads in the second embodiment of the present invention;

[0037] Figure 7 This is a comparison diagram of load damage in the same direction on the right and left sides in the second embodiment of the present invention;

[0038] Figure 8This is a schematic diagram of the load history in the X and Z directions of the front axle of a 2.4T vehicle in the second embodiment of the present invention;

[0039] Fig. 9 This is the Fx-Fz coupling damage distribution diagram in the second embodiment of the present invention;

[0040] Fig.10 It is the damage value and five-level load spectrum in the second embodiment of the present invention. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0043] Embodiment 1

[0044] This embodiment provides a method for compiling a front axle durability rapid test load spectrum, including:

[0045] Based on the front axle load spectra of 8.5T and 4.5T heavy-duty vehicles measured under the same test field road and test specifications, the peak and valley values ​​of the heavy-duty vehicle load history are first extracted and normalized to obtain the relative dynamic load coefficient-frequency histogram. Secondly, the failure locations and damage contributions caused by loads in different directions are evaluated. According to the conservative principle of the bench test, the dynamic load history of the 2.4T front axle is constructed. The constructed load history is analyzed in the time domain and the difference between wheels is analyzed. The load history of the left and right wheels is unified. Then, multi-axis coupling damage assessment is performed to achieve dimensionality reduction of the load. Finally, a five-level load spectrum is compiled and transferred to the highest level to obtain the fast load spectrum of the bench test.

[0046] Based on the existing heavy-duty vehicle load history, peak and valley values ​​were extracted and normalized, and the impact intensity of loads of different models was compared. The front axle load of the 4.5T model with a greater impact intensity was selected as the basis for compiling the front axle load of the 2.4T model.

[0047] Taking the XZ plane as the reference, a direction is determined every 10°, and a total of 19 directions are determined. The damage value generated by the load history in each direction is calculated respectively, and multi-axial damage assessment is performed. Based on the assessment results, the multi-axial load is reduced in dimension.

[0048] Based on the conclusion: the impact intensity of light vehicles is higher than that of heavy vehicles, the load amplitude obtained in step 7 is corrected by taking a correction factor of 1.1, that is, the load amplitude is increased by 10%.

[0049] Specifically, the present invention provides a method for compiling a load spectrum for a front axle durability rapid test, comprising:

[0050] Unit loads in different directions are applied to the front axle of a heavy vehicle. This process is regarded as the load history of the front axle. The failure location and damage contribution value of the front axle in the load history are analyzed.

[0051] In the process of analyzing the failure location and damage contribution value of the front axle in the load history, different directions include X, Y, and Z directions, and only the failure location and damage contribution value in the X and Z directions are analyzed;

[0052] Obtain the peak and valley values ​​of the front axle in the load history, perform normalization on the load history of the front axle, and obtain the relative dynamic load coefficient based on the peak and valley values;

[0053] The process of obtaining the peak-valley values ​​of the front axle in the load history also includes obtaining a peak-valley value-frequency distribution diagram based on the peak-valley values; the process of obtaining the relative dynamic load coefficient load history based on the relative dynamic load coefficient also includes: obtaining a relative dynamic load coefficient-frequency distribution diagram based on obtaining the relative dynamic load coefficient;

[0054] Construct the load history of the front axle of a light vehicle based on the relative dynamic load coefficient;

[0055] The load history of the front axle of the light vehicle is analyzed by analyzing the time domain characteristics of the left and right side loads and the difference between the wheels, so as to obtain the load history of the side with a greater damage contribution value, and the front axle acceleration load spectrum is compiled based on this load history;

[0056] The process of analyzing the time domain characteristics of the left and right side loads and the difference between the wheels for the front axle load history of a light vehicle includes:

[0057] The time domain characteristics of the left and right side loads of the front axle load history of the light vehicle are analyzed, and the time domain synchronization of the left and right side loads of the front axle is compared;

[0058] By compiling the acceleration spectrum on the side with the largest damage contribution value, the load on the left and right sides of the front axle is normalized.

[0059] The load coupling damage assessment in the Fx and Fz directions is performed on the two-dimensional plane where the front axle of the light vehicle is located, and the damage contribution values ​​generated in different directions are obtained and dimensionality reduction is performed. The specific process includes:

[0060] Taking the two-dimensional plane where the front axle of the light vehicle is located as the reference, a direction is determined every 10°, and a total of 19 directions are determined;

[0061] Calculate the damage contribution value generated by the load history in each direction, conduct multi-axial damage assessment, obtain the assessment results, and perform dimensionality reduction processing on the multi-axial load based on the assessment results;

[0062] The load spectrum of the front axle durability rapid test is compiled based on the Fx and Fz load history of the front axle of a light vehicle. The specific process includes:

[0063] The process of compiling the load spectrum of the front axle durability rapid test based on the Fx and Fz load history of the front axle of a light vehicle includes:

[0064] Based on the rain flow counting method, the load history in Fx and Fz directions is counted to obtain the number of load cycles under each stress range;

[0065] Based on the linear cumulative damage formula, the damage corresponding to each level of load is calculated, and the five-level load spectrum is edited;

[0066] Based on the damage equivalence principle, each level of load is transferred to the highest level;

[0067] Obtain the durability bench load spectrum of the front axle of a light vehicle;

[0068] The process of obtaining the durability bench load spectrum of the front axle of a light vehicle includes:

[0069] Obtain the load amplitude after each level of load is transferred to the highest level, increase the load amplitude by 10%, and multiply it with the vertical force when the light vehicle is fully loaded at rest to obtain the light vehicle front axle durability bench load spectrum.

[0070] Embodiment 2

[0071] The overall implementation scheme of the present invention is as follows Figure 1 As shown, it includes the damage contribution and failure location analysis of the front axle structure under loads in different directions, the peak and valley value distribution characteristics analysis of heavy-duty vehicle loads, the normalization processing of heavy-duty vehicle load data, the construction of the front axle load history of 2.4T models, the time domain characteristics analysis of left and right side loads, the wheel difference analysis, the normalization of left and right side loads, the dimensionality reduction processing of multi-axis loads, and the compilation of accelerated test load spectra. The specific implementation steps are as follows:

[0072] Step 1: Use the finite element analysis method to apply unit loads in the X, Y, and Z directions to the front axle, and compare and analyze the failure locations and damage contributions of the front axle structure when subjected to loads in different directions.

[0073] Figure 2 This is the front axle load history of some heavy vehicles.

[0074] like Figure 2As shown in the figure, the failure locations caused by the X- and Z-direction loads are consistent. The Y-direction load value is small and contributes little to the damage of the front axle. The damage caused by the Y-direction load can be ignored, and only the X- and Z-direction load histories are analyzed.

[0075] Step 2: extract and count the peak and valley values ​​of the X and Z direction load time history of the front axle of the 8.5T and 4.5T models to obtain the peak and valley value-frequency distribution diagram of the corresponding load history.

[0076] Figure 3 This is the load peak and valley value-frequency distribution diagram for 8.5T and 4.5T models.

[0077] Step 3: Normalize the X and Z load time histories of the front axles of the 8.5T and 4.5T models, and divide the peak and valley values ​​by the vertical force Fz of each model when fully loaded, to obtain the relative dynamic load coefficient-frequency distribution diagram of the front axle load of the 8.5T and 4.5 models. The relative dynamic load coefficient is:

[0078]

[0079] where F i is the load peak-to-valley value that changes with time; F z is the vertical force of each vehicle type when fully loaded statically.

[0080] The impact intensity of the front axle loads of the two models was compared and analyzed. Based on the conservative principle of bench test, the more dangerous front axle load of the 4.5T model was selected as the basis, and the relative dynamic load coefficient load history of the front axle of the 2.4T model was constructed.

[0081] Figure 4 This is the relative dynamic load coefficient-frequency distribution diagram of 8.5T and 4.5T models.

[0082] Figure 5 It is the load history of the relative dynamic load coefficient of the front axle of the 2.4T model.

[0083] like Figure 4 As shown in the figure, compared with the 8.5T model, the relative dynamic load coefficient range of the 4.5T model front axle load is larger, and the frequency of the same dynamic load coefficient is also higher. Therefore, the impact intensity of the 4.5T model front axle load is greater. The more dangerous 4.5T model front axle load is selected as the basis to construct the following Figure 5 The relative dynamic load coefficient load history of the front axle of the 2.4T model is shown.

[0084] Step 3, Figure 5 The load history constructed in the paper is used to analyze the time domain characteristics of the loads on the left and right sides, and the time domain synchronization of the loads on the left and right sides is compared.

[0085] Figure 6 It is the time domain characteristic diagram of the left and right side loads.

[0086] like Figure 6 As shown in the figure, the loads on the left and right sides have good synchronization in the time domain, and the load history on both sides can be normalized when conducting bench tests.

[0087] Step 5, Figure 5 The load history constructed in the experiment is used to analyze the wheel-to-wheel differences, compare the damage contributions of loads in different directions and on different sides, select the more dangerous side load for acceleration spectrum compilation, and realize the normalization of the left and right side loads in the bench test.

[0088] This application only compiles the acceleration spectrum once. The purpose of performing the time domain characteristic analysis of the left and right side loads and the wheel difference analysis on the front axle load history in step 5 is to determine the load history for subsequent acceleration spectrum compilation, rather than directly compiling the acceleration spectrum.

[0089] Figure 7 This is a comparison diagram of the damage caused by the load in the same direction on the right and left sides.

[0090] Figure 8 It is the X and Z direction load history of the front axle of the 2.4T model.

[0091] like Figure 7 As shown in the figure, the damage contribution of the X and Z loads on the right side is greater than that of the loads on the left side. Therefore, the more dangerous load history on the right side is selected to compile the acceleration spectrum. Figure 8 Load history shown.

[0092] Step 6: Based on the XZ plane, perform load coupling damage assessment in the Fx-Fz direction. On the XZ plane, determine a direction every 10°, for a total of 19 directions. Use the PotentialDamage module in Ncode to calculate and compare the damage values ​​generated by the load history in each direction.

[0093] Fig. 9 It is the Fx-Fz coupling damage distribution diagram.

[0094] like Fig. 9 As shown in the figure, the maximum damage occurs in the direction with an angle of 10° with Fz, and its damage value is only 3% different from that in the Fz direction. Therefore, the multi-axial loading situation can be reduced in dimension, and the X and Z direction load spectra can be loaded separately during the bench test.

[0095] Step 7, based on the load history in Fx and Fz directions determined in step 5, the load spectrum of the front axle durability rapid test is compiled. First, the load history in Fx and Fz directions is counted using the rain flow counting method to obtain the number of load cycles under each stress range, and then the Miner linear cumulative damage formula is used to calculate the damage corresponding to each level of load and compile a five-level load spectrum. The damage corresponding to each level of load cycle is:

[0096]

[0097] Where n i is the actual number of load cycles at each level; N i is the life under various levels of load.

[0098] Afterwards, according to the damage equivalence principle, each level of load is transferred to the highest level.

[0099] Fig.10 is the damage value and the five-level load spectrum.

[0100] like Fig.10 As shown in the figure, according to the damage equivalence principle, the above load history can be compiled into a five-level load spectrum, and each level of load can be transferred to the highest level. A small cycle of the test field is equivalent to 31 equal-amplitude tests of the highest level load in the X direction and 11 equal-amplitude tests of the highest level load in the Z direction.

[0101] Step 8, based on the analysis conclusion of step 3: the impact intensity of light vehicles is higher than that of heavy vehicles, increase the load amplitude obtained in step 7 by 10%, and multiply it by the vertical force Fz of the 2.4T model when it is fully loaded, to obtain the front axle durability bench test load spectrum of the 2.4T model.

[0102] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for compiling a load spectrum for a front axle durability rapid test, characterized in that: The following steps are involved: Apply unit loads in different directions to the front axle of the heavy vehicle, take this process as the load history of the front axle, and analyze the failure position and damage contribution value of the front axle in the load history; Acquire peak-valley values ​​of the front axle in the load history, and acquire a relative dynamic load coefficient based on the peak-valley values; Constructing a front axle load history of a light vehicle based on the relative dynamic load coefficient; Performing time domain characteristic analysis of left and right side loads and wheel-to-wheel difference analysis on the front axle load history of the light vehicle to obtain the load history of the side with a greater damage contribution value; Based on the load history of the side with a larger damage contribution value, load coupling damage assessment in Fx and Fz directions is performed on the two-dimensional plane where the front axle of the light vehicle is located, and damage contribution values ​​generated in different directions are obtained and dimensionality reduction processing is performed; Based on the Fx and Fz load history of the front axle of the light vehicle, a front axle durability rapid test load spectrum is compiled; In the process of analyzing the failure location and damage contribution value of the front axle in the load history, the different directions include three directions of X, Y, and Z, and only the failure location and damage contribution value in the X direction and the Z direction are analyzed; Before obtaining the relative dynamic load coefficient based on the peak-to-valley value, the method further includes: normalizing the load history of the front axle; The process of analyzing the time domain characteristics of the left and right side loads and the difference between the wheels of the front axle load history of the light vehicle includes: Performing time domain characteristic analysis of left and right side loads on the front axle load history of the light vehicle, and comparing the time domain synchronization of the left and right side loads of the front axle; Normalization of the loads on the left and right sides of the front axle is achieved by compiling an acceleration spectrum for the side with a larger damage contribution value; The process of performing load coupling damage assessment in the Fx-Fz direction on the two-dimensional plane where the front axle of the light vehicle is located, obtaining damage contribution values ​​generated in different directions and performing dimensionality reduction processing includes: Taking the two-dimensional plane where the front axle of the light vehicle is located as a reference, a direction is determined every 10°, and a total of 19 directions are determined; Calculate the damage contribution value generated by the load history in each direction, perform multi-axis damage assessment, and obtain the assessment results; Performing dimensionality reduction processing on the multi-axial load based on the evaluation results; The process of compiling the load spectrum of the front axle durability rapid test based on the Fx and Fz load history of the front axle of the light vehicle includes: Based on the rain flow counting method, the load history in Fx and Fz directions is counted to obtain the number of load cycles under each stress range; Based on the linear cumulative damage formula, the damage corresponding to each level of load is calculated, and the five-level load spectrum is edited; Based on the damage equivalence principle, each level of load is transferred to the highest level; Obtain the durability bench load spectrum of the front axle of a light vehicle; The process of obtaining the durability bench load spectrum of the front axle of a light vehicle includes: The load amplitude after each level of load is transferred to the highest level is obtained, the load amplitude is increased by 10%, and multiplied by the vertical force when the light vehicle is fully loaded at rest, to obtain the durability bench load spectrum of the light vehicle front axle.

2. The method according to claim 1, characterized in that The process of obtaining the peak-valley values ​​of the front axle in the load history also includes obtaining a peak-valley value-frequency distribution diagram based on the peak-valley values; The process of obtaining the relative dynamic load coefficient load history based on the relative dynamic load coefficient further includes: obtaining a relative dynamic load coefficient-frequency distribution diagram based on the obtaining of the relative dynamic load coefficient.

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