A method for compiling load spectrum for half-axle life test

Abstract

The present invention provides a method for compiling a load spectrum for a semi-axle life test, comprising the following steps: collecting load spectrum data of the semi-axle, and preprocessing the load spectrum data; establishing a damage calculation model under a failure-dominant load spectrum; based on the damage calculation model under a failure-dominant load spectrum, performing semi-axle damage calculation on the preprocessed load spectrum data, and obtaining a semi-axle damage contribution distribution result; based on the semi-axle damage contribution distribution result, obtaining a characteristic operating condition level and a corresponding proportional relationship; based on the damage caused by the load collected on the actual road, using a mileage extrapolation method, obtaining a semi-axle full life cycle damage target; based on the semi-axle full life cycle damage target and the characteristic operating condition level and the corresponding proportional relationship, obtaining the number of life test load spectrum cycles, and completing the compilation of the life test load spectrum. The present invention can effectively verify the reliability level of the semi-axle, accelerate the test process, shorten the product verification test time, and provide technical support for the high-quality development of the semi-axle.

Description

Technical Field

[0001] The invention belongs to the technical field of reliability analysis of a half-shaft, and in particular relates to a method for compiling a load spectrum for a half-shaft life test. Background Art

[0002] In recent years, new energy vehicles have become an important engine for the transformation and development of the global automotive industry and for promoting world economic growth. The half-shaft is mainly composed of an outer ball cage universal joint, an inner ball cage universal joint and a half-shaft rod, which is responsible for connecting the differential with the drive wheel. Due to the characteristics of the new energy vehicle drive motor with a wider speed regulation range and a large starting torque, it puts forward higher requirements on the stability, reliability and durability of the half-shaft. At present, there are relatively few life test load spectra and evaluation technical specifications for half-shafts. For the reliability assessment of a single component, a high-acceleration life evaluation method with continuous loading under simple working conditions is often used, but it is difficult to effectively cover the multi-condition variable amplitude load history that the half-shaft is subjected to during actual use by users. To this end, the present invention collects load data based on actual roads, constructs a life test load spectrum associated with the actual failure mode of the half-shaft, which can effectively verify the reliability level of the half-shaft and provide technical support for its high-performance development. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a method for compiling a half-shaft life test load spectrum. The method is associated with the actual failure mode of the half-shaft and constructs a half-shaft multi-condition variable amplitude loading test load spectrum, which can effectively verify the reliability level of the half-shaft, accelerate the test process, shorten the product verification test time, and provide technical support for the high-quality development of the half-shaft.

[0004] To achieve the above object, the present invention provides a method for compiling a half-axle life test load spectrum, comprising the following steps:

[0005] Collecting load spectrum data of the semi-axle and preprocessing the load spectrum data;

[0006] Establish a damage calculation model under the failure-dominant load spectrum;

[0007] Based on the damage calculation model under the failure-dominant load spectrum, the semi-axle damage calculation is performed on the pre-processed load spectrum data to obtain the semi-axle damage contribution distribution result;

[0008] Based on the semi-axle damage contribution distribution result, the characteristic working condition level and the corresponding proportional relationship are obtained;

[0009] Based on the damage caused by the load collected on the actual road, the mileage extrapolation method is used to obtain the damage target of the half-axle throughout its life cycle;

[0010] Based on the half-shaft full life cycle damage target and the characteristic operating condition level and the corresponding proportional relationship, the number of cycles of the life test load spectrum is obtained, and the compilation of the life test load spectrum is completed.

[0011] Optionally, the load spectrum data is mainly the half-shaft failure dominant load, including: half-shaft speed, half-shaft torque and half-shaft angle.

[0012] Optionally, the process of preprocessing the load spectrum data is:

[0013] The half-shaft speed is sliced ​​according to load levels, and within each slice, the half-shaft angle and the half-shaft torque are counted for joint distribution to obtain frequency distribution characteristics under different load levels.

[0014] Optionally, the method for establishing the damage calculation model under the dominant load spectrum is:

[0015] Based on the Archard wear model and the failure dominant load spectrum, a damage calculation model under the dominant load spectrum is established: Where w is the wear amount, k is the wear coefficient, P is the contact pressure, H is the material hardness, L is the wear distance; T is the torque, α is the angle, and n is the rotation speed.

[0016] Optionally, the method for obtaining the semi-axis damage contribution distribution result is:

[0017] Based on the damage calculation model under the dominant load spectrum, the damage of the half-shaft under different speed slices, different angles and torque levels is calculated to obtain the half-shaft damage contribution distribution result.

[0018] Optionally, the method for obtaining the proportional relationship corresponding to the characteristic operating condition level is:

[0019] For a given target angle and torque condition, according to the damage contribution distribution characteristics at different angles and torques, the damage with a damage contribution greater than the threshold is transferred to the target interval to obtain the damage contribution ratio within the preset slice;

[0020] Based on the damage contribution ratio in each slice, the proportional relationship under the characteristic working condition level is obtained.

[0021] Optionally, the method for obtaining the life test load spectrum level is:

[0022] The speed level in the life test load spectrum is taken as the interval mean of each slice, and the angle and torque at each speed level are rounded to obtain the time proportion under the load level in each slice;

[0023] The time proportions under the load levels in each slice are matched to obtain the life test load level.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] The present invention discloses a method for compiling a half-axle life test load spectrum. Based on the actual road load of the user's half-axle, the load is sliced ​​according to the rotational speed, and a joint counting method is applied to the angle and torque in different slices to count the action frequency of each load level in the actual service load. The constructed life test load spectrum is associated with the actual failure mode of the half-axle, which can effectively verify the reliability level of the half-axle, shorten the entire test time, accelerate the entire test process, and provide support for the high-quality development of the half-axle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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:

[0027] Figure 1 It is a schematic flow chart of a method for compiling a load spectrum for a half-axle life test in this embodiment;

[0028] Figure 2 This is a schematic diagram of partial load data of the actual road load data collected from the half-axle in this embodiment;

[0029] Figure 3 is a schematic diagram of slicing load (0-100rpm) according to the rotation speed in this embodiment;

[0030] Figure 4 is the angle and torque joint distribution count distribution histogram of the load in the 0-100 rpm slice in this embodiment;

[0031] Figure 5 is a load damage contribution surface diagram of different load angles and different torques within the slice (0-100rpm) in this embodiment;

[0032] Figure 6 is the cumulative damage contribution distribution diagram at different angle levels of load within the slice (0-100rpm) in this embodiment;

[0033] Figure 7 is a distribution diagram of cumulative damage contribution at different torque levels of load within the slice (0-100 rpm) in this embodiment;

[0034] Figure 8 Schematic diagram of different load angles, torque damage contribution distribution and characteristic working condition selection in the slice (0-100rpm) in this embodiment;

[0035] Fig. 9 is the damage contribution distribution diagram of the loads in different slices in this embodiment;

[0036] Fig.10 It is the load spectrum cycle condition diagram of the half-axle life test in this embodiment. DETAILED DESCRIPTION

[0037] 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.

[0038] 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.

[0039] Example

[0040] like Figure 1 As shown, this embodiment provides a method for compiling a load spectrum for a half-axle life test, including load slicing of half-axle load data, half-axle wear life model under failure dominant load, half-axle damage analysis, determination of the level of accelerated test characteristic conditions and the proportional relationship between characteristic conditions, determination of half-axle full life cycle damage target, and compilation of life test load spectrum. The specific implementation steps are as follows:

[0041] Step 1: Collect load data based on the actual road conditions of the half-axle. The load data includes the half-axle torque, speed, and the angle generated by the wheel. Take the half-axle speed as the object and slice the load level in the interval of 100r / min. In each slice, count the joint distribution of the half-axle angle and torque load, and count the action frequency under different load levels.

[0042] In this embodiment, step 1 slices the load based on the load data collected on the actual road, and counts the angle and torque in each slice to obtain the frequency distribution characteristics under each level of load. Figure 2 As shown. Taking the speed as the object, the load data is sliced ​​into 0-100 (r / min), 100-200 (r / min) ... 1000-1100 (r / min), a total of 11 slices. The schematic diagram of the load slice 0-100 (r / min) is as follows Figure 3 The present invention divides the angle torque into 24 levels. Within the 0-100rpm slice, the results after load counting are as follows: Figure 4 As shown in the figure, the angle-torque joint distribution histogram shows that the frequency of occurrence is higher at small angles and small torques, while the frequency of load counts is lower at large angles and large torques.

[0043] Step 2, establish a half-shaft damage calculation model. The present invention adopts the Archard wear model combined with the failure dominant load w for the outer universal joint in the half-shaft as follows:

[0044]

[0045] Where w is the wear amount, k is the wear coefficient, P is the contact pressure, H is the material hardness, L is the wear distance; T is the torque, α is the angle, and n is the rotation speed.

[0046] In this embodiment, it can be known from the Archard wear model that the dominant loads are the contact force and the wear distance. For the half-shaft outer universal joint component, the half-shaft torque corresponds to the contact force, and the half-shaft speed and angle product corresponds to the wear distance.

[0047] Step 3: Calculation and analysis of half-shaft damage. By calculating half-shaft damage at different speed slices, different angles, and torque levels, we can obtain the half-shaft damage contribution distribution results. Figure 5 As shown in the figure, the half-axle universal joint has the highest damage contribution at small angles and small torques, and less damage contribution at large angles and large torques.

[0048] In this embodiment, in order to clarify the difference in damage contribution under different load levels, the load level with higher cumulative damage contribution is screened out as the basis for selecting the load spectrum for the life test. In the present invention, the cumulative damage intensity under different angles and torque levels in each slice is statistically analyzed. For example, in the slice (0-100rpm), Figure 6 and Figure 7 As shown, the damage contribution is higher when the angle is near [-0.5°, 1.2°], and the damage contribution is highest when the torque is near 24Nm.

[0049] Step 4, determination of characteristic operating condition level and corresponding proportional relationship. When determining the life test load level, the present invention is based on the following principles: it is necessary to cover the half-axle damage contribution distribution characteristics; the selection of characteristic operating conditions must include typical operating conditions in the load data collected on the actual road, and should also have a higher damage contribution; in addition, the load spectrum must also include extreme load conditions. In determining the time proportional relationship of the characteristic operating condition level within the slice, for a given target angle and torque condition, according to the damage contribution distribution characteristics of different angles and different torques, the load with a large damage contribution is transferred to the target interval, so as to obtain the time proportion under the load level within the slice; and the time proportional relationship of the characteristic operating condition level between each slice is determined by the damage contribution ratio of each slice.

[0050] In this embodiment, according to the cumulative distribution characteristics of the damage contribution of the semi-axle, the typical load in the slice is selected: taking the 0-100rpm slice as an example (the same applies to the other slices), the damage contribution is higher when the angle is in the range [-0.5°, 1.2°] and the torque is in the range [-457Nm, 24Nm]. At the same time, the angle and torque are divided into four major blocks with 0 as the dividing line, such as Figure 8 As shown, the red one is the selected characteristic working condition. The maximum damage contribution load [-0.5°, 24Nm] is selected as the main representative working condition of this slice. Taking into account the extreme working conditions and the characteristics that the loads on the half-axis are one positive and one negative, the upper left corner [-2.7°, 231Nm] and the lower right corner [2.5°, -938Nm] are selected as extreme loads;

[0051] Determination of characteristic working condition level time proportion: also based on the cumulative distribution characteristics of the damage contribution of the half shaft. For the slice, such as the 0-100rpm slice in this example (the same applies to other slices), the angle range [-0.5°, 1.2°] with higher damage contribution and the torque range [-457, 24] Nm with cumulative damage contribution and 60% are taken as the proportion of the main representative working condition, such as Figure 8 The sum of the yellow area, and the other two extreme conditions are 20%. For the slices, it is determined according to the proportion of the damage in each slice to the total damage, that is: the damage contribution distribution between different slices, such as Fig. 9 shown.

[0052] In this embodiment, the characteristic working condition levels and proportions are shown in Table 1:

[0053] Table 1

[0054]

[0055] Step 5, determine the damage target of the half-axle during the whole life cycle. In the process of compiling the acceleration test load spectrum, it is necessary to clarify the damage target reached by the half-axle in the whole life cycle of 300,000 kilometers, so as to determine the number of cycles of the life test load spectrum. In the embodiment of the present invention, the mileage extrapolation method is adopted for the damage target of the whole life cycle, and the damage value caused by the load collected on the actual road to the half-axle and the total damage target are counted, as shown in Table 2.

[0056] Table 2

[0057]

[0058] Step 6, life test load spectrum preparation. The half-axle life test load spectrum should include 33 load condition levels in this embodiment, where the speed level takes the interval mean of each slice, and the angle and torque are rounded. Finally, the life test load level is matched after the time of each level is matched as shown in Table 3. 5 seconds is used as the transition time when each load changes, and the final single cycle time is 3820 seconds, a total of 202 cycles, where the single cycle condition time history is as follows Fig.10 shown.

[0059] Table 3

[0060]

[0061] The above are only preferred specific implementations 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 half-axle life test, characterized in that: The following steps are involved: Collecting load spectrum data of the semi-axle and preprocessing the load spectrum data; Establish a damage calculation model under the failure-dominant load spectrum; Based on the damage calculation model under the failure-dominant load spectrum, the semi-axle damage calculation is performed on the pre-processed load spectrum data to obtain the semi-axle damage contribution distribution result; Based on the semi-axle damage contribution distribution result, the characteristic working condition level and the corresponding proportional relationship are obtained; Based on the damage caused by the load collected on the actual road, the mileage extrapolation method is used to obtain the damage target of the half-axle throughout its life cycle; Based on the half-shaft full life cycle damage target and the characteristic operating condition level and the corresponding proportional relationship, the number of cycles of the life test load spectrum is obtained, and the compilation of the life test load spectrum is completed; The load spectrum data is mainly the dominant load of the half-shaft failure, including: half-shaft speed, half-shaft torque and half-shaft angle; The process of preprocessing the load spectrum data is as follows: Slicing the half-shaft speed by load level, and performing joint distribution counting on the half-shaft angle and the half-shaft torque in each slice to obtain frequency distribution characteristics under different load levels; The method to obtain the semi-axis damage contribution distribution results is: Based on the damage calculation model under the dominant load spectrum, the damage of the half shaft under different speed slices, different angles and torque levels is calculated to obtain the half shaft damage contribution distribution result; The method for obtaining the proportional relationship corresponding to the characteristic working condition level is: For a given target angle and torque condition, according to the damage contribution distribution characteristics at different angles and torques, the damage with a damage contribution greater than the threshold is transferred to the target interval to obtain the damage contribution ratio within the preset slice; Based on the damage contribution ratio in each slice, a proportional relationship under a characteristic working condition level is obtained; The method to obtain the life test load spectrum level is: The speed level in the life test load spectrum is taken as the interval mean of each slice, and the angle and torque at each speed level are rounded to obtain the time proportion under the load level in each slice; The time proportions under the load levels in each slice are matched to obtain the life test load level.

2. The method for compiling a load spectrum for a semi-axle life test according to claim 1, characterized in that: The method to establish the damage calculation model under the dominant load spectrum is: Based on the Archard wear model and the failure dominant load spectrum, a damage calculation model under the dominant load spectrum is established: , where w is the wear amount, k is the wear coefficient, P is the contact pressure, H is the material hardness, L is the wear distance; T is the torque, α is the angle, and n is the rotation speed.

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