An accelerated durability test method for commercial vehicle cooling modules based on FDS-FDAT

Abstract

The present invention discloses an accelerated durability test method for a commercial vehicle cooling module based on FDS-FDAT. Based on the vibration response signal of the cooling module obtained by a vibration acceleration sensor in a real vehicle road test, the failure risk road condition is located according to the modal characteristics and stress analysis results of the cooling module. The signal characteristic components that retain the failure risk road condition are calculated through fatigue damage theory, and then the acceleration power spectrum density PSD editing is completed; the experimental test technology is closely combined with the signal processing technology, wherein the experimental test obtains accurate real signals containing a variety of road condition information, and a variety of algorithms are used to calculate and screen the signals according to the targeted characteristics to determine the vibration source, further complete the accelerated test, and complete the bench simulation test. The present invention solves the problem of multi-factor interference in road simulation tests, and effectively reproduces the damage and destruction forms in the cooling module road test, and shortens the test cycle of indoor bench tests.

Description

Technical Field

[0001] The present invention relates to the NVH field of commercial vehicle cooling modules and durability test fault diagnosis of commercial vehicle cooling modules. The accelerated durability test method of commercial vehicle cooling modules based on FDS-FDAT can effectively identify high-risk failure road conditions in road tests, and then conduct bench simulation tests in a targeted manner, so that the durability test cycle of the cooling module is greatly shortened and fault reproduction is achieved, and then an optimization plan is further proposed. Background Art

[0002] Reducing vibration, extending service life, and reducing failure rate are important research directions for commercial vehicle cooling modules. To effectively diagnose commercial vehicle cooling module faults, accurately identify the main vibration road conditions that cause failures, and verify the problems in bench tests, shortening the test cycle is the key. Commercial vehicle road test conditions are more demanding, the excitation frequencies are more diverse and complex, and the complex response process transmitted through the vibration path is the main reason for the ultimate failure of the cooling module. Therefore, the cooling module needs to consider the complexity of road tests in indoor bench tests, accurately reproduce the risky road conditions in road tests, and thus shorten the test cycle.

[0003] Compared with the traditional vibration durability test method, the accelerated durability test method of commercial vehicle cooling module based on FDS-FDAT can more effectively identify dangerous road conditions in durability tests, and can fully retain the characteristics of vibration damage from the time-frequency domain. This method has been successfully applied in the field of NVH and durability fault diagnosis of commercial vehicle cooling modules. The specific accelerated durability test methods used include fatigue damage spectrum analysis and frequency domain acceleration theory. Among them, the traditional vibration durability test method based on random signal power spectrum density obtains its power spectrum density PSD from the transformation of random signals, lacks video analysis of each road condition, resulting in its durability test. The excitation characteristics in dangerous road conditions cannot be accurately and effectively retained, and the vibration characteristics cannot be accurately restored. The present invention better retains the frequency domain characteristics of the load spectrum in road tests based on fatigue damage spectrum and frequency domain acceleration theory, and effectively shortens the test cycle. This method is suitable for cooling modules and air-conditioning systems of the same type of commercial vehicles.

[0004] In summary: Based on the multi-condition, non-stationary, and strongly excitatory vibration response signals of the cooling module, the patent of this invention proposes an accelerated durability test method for commercial vehicle cooling modules based on FDS-FDAT. This technology combines the finite element analysis results, fatigue damage spectrum theory, and vibration acceleration factor algorithm to successfully identify high failure risk road conditions in road tests, and based on this, edits and calculates the bench test excitation spectrum containing multiple road condition characteristics, providing sufficient basis for commercial vehicle cooling module durability test verification and fault optimization. Summary of the invention

[0005] In order to overcome the shortcomings of existing bench vibration tests, the present invention provides an accelerated durability test method for commercial vehicle cooling modules based on FDS-FDAT. The present invention more closely links fatigue damage with frequency domain vibration acceleration theory, and uses an algorithm to obtain the bench test acceleration power spectrum density PSD that retains multiple road condition characteristics through the fatigue damage theory of the signal obtained by direct testing, and then combines the frequency domain acceleration theory (Frequency domain acceleration theory) to accelerate and amplify the acceleration power spectrum density PSD in the frequency domain, and establish an acceleration relationship corresponding to the test duration. This set of invention processes that combines experimental testing with algorithms and finally uses bench testing successfully completed the bench accelerated durability test.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] An accelerated durability test method for commercial vehicle cooling modules based on FDS-FDAT;

[0008] The cooling module accelerated durability test system of the present invention comprises: a failure position vibration acceleration sensor and a cooling module of a commercial vehicle to be tested; the host computer is connected to the failure position vibration acceleration sensor;

[0009] The failure position vibration acceleration sensor is installed at the failure position of the cooling module of the commercial vehicle to be tested;

[0010] The cooling module accelerated durability test system is installed on a commercial cooling vehicle;

[0011] Step 1: The commercial cooling vehicle is driven under different road conditions, and the three-axis vibration acceleration signals of the failure position at multiple times under each road condition are collected by the failure position vibration acceleration sensor, and transmitted to the host computer; the three-axis vibration acceleration signals of the non-failure position at multiple times under each road condition are collected by the non-failure position vibration acceleration sensor, and transmitted to the host computer; the three-axis directions are respectively X direction, Y direction, and Z direction; the three-axis vibration acceleration signals of the failure position at multiple times under various road conditions are further calculated by power spectral density to obtain a power spectral density data set for each road condition, and multiple power spectral density peaks for each road condition are extracted;

[0012] Step 2: Perform modal simulation analysis on the cooling module finite element model through finite element analysis software to obtain the modal frequency and vibration mode of the cooling module; combine the modal frequency, vibration mode of the cooling module, and the power spectrum density data set of each road condition to calculate the stress result of the cooling module for each road condition using the modal superposition method, and compare the stress results of the cooling module for multiple road conditions with the normal range of stress results in turn. If the stress result of the cooling module for a road condition exceeds the normal range of stress results, the road condition is determined to be a failure risk road condition, thereby obtaining multiple failure risk road conditions.

[0013] Step 3: Perform fatigue damage spectrum analysis in sequence on the vibration acceleration signals of the three-axis directions of the non-failed positions at multiple moments of the multiple failure risk road conditions described in step 2 to obtain the fatigue damage spectrum of each failure risk road condition, perform linear superposition of the fatigue damage spectra of multiple failure risk road conditions according to Miner linear fatigue accumulation theory to obtain the total fatigue damage spectrum of the dangerous road condition, and obtain the multi-road condition acceleration power spectrum density acting on the bench durability test according to the inverse formula of the total fatigue damage spectrum of the dangerous road condition;

[0014] Step 4: The acceleration power spectrum density of multiple road conditions acting on the bench endurance test is accelerated and amplified by the frequency domain acceleration method to obtain the bench test acceleration power spectrum density with the same fatigue damage amount and a shortened test cycle, and the vibration acceleration factor of the endurance test is further calculated based on the bench test acceleration power spectrum density with the same fatigue damage amount and a shortened test cycle;

[0015] Compared with the traditional indoor bench endurance test, the random vibration signal of all road conditions is subjected to acceleration power spectrum density PSD analysis, and then loaded onto the test bench for endurance test. The advantage of the present invention is that starting from the frequency domain characteristics of independent road conditions, according to the modal characteristics of the cooling module and the stress analysis results, the failure risk road conditions are located. The signal characteristic components of the failure risk road conditions are obtained through fatigue damage theory calculation, and then the acceleration power spectrum density PSD editing is completed;

[0016] FDS-FDAT's commercial vehicle cooling module accelerated durability test method closely combines experimental testing technology with signal processing technology. The experimental test obtains accurate real signals containing a variety of road condition information, and uses a variety of algorithms to target the characteristics of these signals. Finally, digital signal processing technology is used to calculate and screen the signals to determine the vibration source, further complete the accelerated test, and finally complete the bench simulation test. This invention successfully solves the multi-factor interference problem in road simulation tests and provides a system for the analysis of such problems in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : It is a flow chart of the method of the present invention.

[0018] Figure 2 :The three-dimensional vibration acceleration signal of a commercial vehicle cooling module in a road test obtained by the vibration acceleration sensor test

[0019] Figure 3 : Multiple power spectrum density peaks of each road condition obtained after spectrum analysis.

[0020] Figure 4 : Modal results of a commercial vehicle cooling module obtained after finite element analysis.

[0021] Figure 5 : It is the stress result under random vibration excitation obtained after finite element analysis.

[0022] Figure 6 : The fatigue damage spectrum of the main road conditions and the total fatigue damage spectrum in three directions are calculated based on the road conditions with greater failure risks.

[0023] Figure 7 :To obtain the acceleration power spectral density PSD curve of bench test based on FDS theory.

[0024] Figure 8 : The acceleration power spectral density PSD curve of the bench accelerated endurance test after the vibration acceleration factor is amplified based on the FDAT theory.

[0025] Fig. 9 : Comparison curve between the fatigue damage spectrum generated by bench test and the fatigue damage spectrum generated by road test.

[0026] Fig.10 : Comparison curve of fatigue damage spectrum produced before and after acceleration of bench test. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, a flow chart of the accelerated durability test method of commercial vehicle cooling module based on FDS-FDAT includes the following steps:

[0029] An accelerated durability test method for commercial vehicle cooling modules based on FDS-FDAT;

[0030] The cooling module accelerated durability test system of the present invention comprises: a failure position vibration acceleration sensor and a cooling module of a commercial vehicle to be tested; the host computer is connected to the failure position vibration acceleration sensor;

[0031] The failure position vibration acceleration sensor is installed at the failure position of the cooling module of the commercial vehicle to be tested;

[0032] The cooling module accelerated durability test system is installed on a commercial cooling vehicle.

[0033] The model of the failure position vibration acceleration sensor is: YMC271A01 standard acceleration sensor;

[0034] Step 1: When the commercial cooling vehicle is driving under different road conditions, the failure position vibration acceleration sensor is used to collect the three-axis vibration acceleration signals of the failure position at multiple times under each road condition, and transmits them to the host computer; the non-failure position vibration acceleration sensor is used to collect the three-axis vibration acceleration signals of the non-failure position at multiple times under each road condition, and transmits them to the host computer; Figure 2 The figure shows the three-dimensional vibration acceleration signal of a commercial vehicle cooling module in a road test obtained by the vibration acceleration sensor test.

[0035] The three-axis directions are X direction, Y direction, and Z direction respectively; the vibration acceleration signals of the three-axis directions of the failure position at multiple times under various road conditions are further calculated by power spectrum density to obtain a power spectrum density data set for each road condition, such as Figure 3 Shown are multiple power spectrum density peaks extracted for each road condition after spectrum analysis;

[0036] Step 2: Perform modal simulation analysis on the cooling module finite element model using finite element analysis software, such as Figure 4To obtain the modal frequency and vibration mode of the cooling module, the modal superposition method is used to calculate the power spectrum density data set of each road condition by combining the modal frequency, vibration mode and power spectrum density data set of each road condition. Figure 5 The stress results of the cooling module for each road condition are shown. The stress results of the cooling module for various road conditions are compared with the normal range of the stress results in turn. If the stress result of the cooling module for a road condition exceeds the normal range of the stress result, the road condition is determined to be a failure risk road condition, thereby obtaining multiple failure risk road conditions.

[0037] Step 3: Perform fatigue damage spectrum analysis on the vibration acceleration signals of the non-failed positions in three axes at multiple times of the multiple failure risk road conditions described in step 2, and obtain Figure 6 The fatigue damage spectrum of each failure risk road condition shown in (a), (b), and (c) is obtained by linearly superposing the fatigue damage spectra of multiple failure risk road conditions according to Miner's linear fatigue accumulation theory. Figure 6 The total fatigue damage spectrum of the dangerous road condition shown in (d) is obtained by inversely calculating the total fatigue damage spectrum of the dangerous road condition as follows: Figure 7 The power spectrum density of multi-road acceleration acting on the bench durability test is shown in Figure 2. When applied to the bench durability test, the fatigue damage spectrum generated is similar to the fatigue damage spectrum generated by the road test. Fig. 9 shown.

[0038] Step 4: Use the frequency domain acceleration method to accelerate and amplify the power spectrum density of the multi-road conditions acting on the bench durability test, and obtain the following Figure 8 The acceleration power spectrum density of the bench test with the same fatigue damage amount and shortened test cycle is shown in FIG. The vibration acceleration factor of the long-term test is further calculated based on the acceleration power spectrum density of the bench test with the same fatigue damage amount and shortened test cycle. The fatigue damage spectrum generated by the bench test after acceleration by the vibration acceleration factor is different from the fatigue damage spectrum without acceleration as shown in FIG. Fig.10 shown.

[0039] The steps are as follows: using FDAT technology to perform frequency domain equivalent acceleration on the bench test acceleration power spectrum density PSD. According to the SN curve parameters of the cooling module material, the original test cycle length T1, and the test cycle length T2 after T acceleration, the vibration acceleration factor of the long-term test is calculated;

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A commercial vehicle cooling module accelerated durability test method based on FDS-FDAT, characterized in that: Step 1: The commercial cooling vehicle is driven under different road conditions, and the three-axis vibration acceleration signals of the failure position at multiple times under each road condition are collected by the failure position vibration acceleration sensor, and transmitted to the host computer; the three-axis vibration acceleration signals of the non-failure position at multiple times under each road condition are collected by the non-failure position vibration acceleration sensor, and transmitted to the host computer; the three-axis directions are respectively X direction, Y direction, and Z direction; the three-axis vibration acceleration signals of the failure position at multiple times under various road conditions are further calculated by power spectral density to obtain a power spectral density data set for each road condition, and multiple power spectral density peaks for each road condition are extracted; Step 2: Perform modal simulation analysis on the cooling module finite element model through finite element analysis software to obtain the modal frequency and vibration mode of the cooling module; use the modal superposition method to calculate the stress result of the cooling module for each road condition by combining the modal frequency, vibration mode of the cooling module, and the power spectrum density data set of each road condition, and compare the stress results of the cooling modules of various road conditions with the normal range of stress results in turn. If the stress result of the cooling module of a road condition exceeds the normal range of stress results, the road condition is determined to be a failure risk road condition, thereby obtaining multiple failure risk road conditions; Step 3: Perform fatigue damage spectrum analysis in sequence on the vibration acceleration signals of the three-axis directions of the non-failed positions at multiple moments of the multiple failure risk road conditions described in step 2 to obtain the fatigue damage spectrum of each failure risk road condition, perform linear superposition of the fatigue damage spectra of multiple failure risk road conditions according to Miner linear fatigue accumulation theory to obtain the total fatigue damage spectrum of the dangerous road condition, and obtain the multi-road condition acceleration power spectrum density acting on the bench durability test according to the inverse formula of the total fatigue damage spectrum of the dangerous road condition; Step 4: The acceleration power spectrum density of multiple road conditions acting on the bench endurance test is accelerated and amplified by the frequency domain acceleration method to obtain the bench test acceleration power spectrum density with the same fatigue damage amount and shortened test cycle. The vibration acceleration factor of the endurance test is further calculated based on the bench test acceleration power spectrum density with the same fatigue damage amount and shortened test cycle.

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