CN-121977849-A - Random vibration test signal conversion method based on damage equivalence

CN121977849ACN 121977849 ACN121977849 ACN 121977849ACN-121977849-A

Abstract

The invention discloses a random vibration test signal conversion method based on damage equivalence, which relates to the technical field of simulation test and comprises the steps of firstly obtaining a time domain vibration signal of a new energy automobile part under a multi-path condition, then obtaining a frequency domain impact response through impact response spectrum calculation, calculating fatigue damage of each frequency point according to the frequency domain impact response, then accumulating to obtain total damage according to road condition circulation times, determining a Power Spectrum Density (PSD) signal capable of generating equivalent damage in preset test time through iterative calculation by taking the total damage as an equivalent target, finally forming a maximum load envelope through extracting maximum values of impact responses under all road conditions, converting the PSD signal into transient response, and comparing the transient response with the envelope to verify the amplitude rationality of the PSD signal. The invention obviously shortens the verification period of the vibration durability of the parts and improves the pertinence and the reliability of the test on the premise of ensuring the consistency of the fatigue damage.

Inventors

GAO DI
PAN XIAOYONG
YU CHAO
SHEN DONGMING
YE LINGWEI
Jin Jinkai

Assignees

宁波拓普集团股份有限公司

Dates

Publication Date: 20260505
Application Date: 20251231

Claims (10)

1. The random vibration test signal conversion method based on damage equivalence is characterized by comprising the following steps: s1, acquiring time domain vibration signals of parts of a new energy automobile under various actual road conditions; s2, obtaining frequency domain impulse response corresponding to each frequency point by performing impulse response spectrum calculation on the time domain vibration signal; s3, calculating fatigue damage caused by vibration of each frequency point based on the frequency domain impact response, and generating a corresponding fatigue damage signal; s4, according to the cycle times of each actual road condition, obtaining a damage accumulation result representing total damage by accumulating fatigue damage signals; S5, determining a power spectrum density signal by iterative calculation by taking a damage accumulation result as an equivalent target, so that vibration fatigue damage generated by the power spectrum density signal within a preset test time is equal to the damage accumulation result; And S6, extracting the maximum value of the frequency domain impulse response under all road conditions as a maximum load envelope, converting the power spectrum density signal into transient response, and comparing the transient response with the maximum load envelope to verify the amplitude rationality of the power spectrum density signal.
2. The method for converting a random vibration test signal based on damage equivalence according to claim 1, wherein in the step S2, the impact response spectrum is calculated by applying a time domain vibration signal to a series of single degree of freedom system models with different natural frequencies, and generating a frequency domain impact response based on the frequency distribution of the maximum value of the system acceleration response.
3. The method for converting a random vibration test signal based on damage equivalence according to claim 2, wherein the natural frequency range setting of the single degree of freedom system model is performed based on vibration characteristics of parts.
4. The method for converting a random vibration test signal based on damage equivalence according to claim 1, wherein in the step S3, the fatigue damage calculating process includes: Converting acceleration responses in the frequency domain impulse response to force responses; calculating a stress amplitude based on the converted force response; And calculating fatigue damage corresponding to each frequency point based on the stress amplitude and a preset S-N curve parameter.
5. The method for converting a random vibration test signal based on damage equivalency of claim 1, wherein in the step S4, fatigue damage signals are accumulated based on Miner' S linear accumulation damage rule.
6. The method for converting a random vibration test signal based on damage equivalence according to claim 1, wherein in the step S5, when determining the power spectrum density signal through iterative calculation, a vibration fatigue damage model based on rayleigh distribution is adopted to estimate damage generated by a given power spectrum density signal within a preset test time.
7. The method for converting a random vibration test signal based on damage equivalency of claim 1, wherein in step S5, when a preset test time is required to be adjusted, the method is based on fatigue strength index The amplitude of the power spectral density signal is adjusted according to the following relation: In the formula, For different preset test times, As a function of the corresponding power spectral density.
8. The method for converting a random vibration test signal based on damage equivalence according to claim 1, wherein in the step S5, the preset test time is selected based on an industry experience database, and the experience database comprises test time requirements of different host factories on similar parts in multiple directions and development standard experience of users.
9. The method for converting a random vibration test signal based on damage equivalence according to claim 1, wherein in the step S6, the process of converting into transient response comprises at least one of reconstructing a power spectrum density signal in a time domain and simulating transient dynamics of the power spectrum density signal.
10. The method of claim 1, wherein in step S6, if the transient response obtained by converting the power spectrum density signal exceeds the maximum load envelope, the method further comprises the steps of extending the preset test time and re-executing step S5.

Description

Random vibration test signal conversion method based on damage equivalence Technical Field The invention relates to the technical field of simulation tests, in particular to a random vibration test signal conversion method based on damage equivalence. Background In the development process of new energy automobiles, the problems of vibration and noise of accessories such as an air conditioner compressor are increasingly prominent due to the disappearance of vibration and noise sources of a traditional engine, and the problems become one of main factors affecting the NVH performance and riding comfort of the whole automobile. To suppress compressor vibration, a rubber vibration isolator is typically used for primary or secondary vibration isolation designs. However, the flexible element used in the vibration isolation system may introduce a lower natural frequency, so that the air compressor system is easily excited to resonate by external excitation, and thus, resonance fatigue failure of key parts such as a bracket may be caused. Therefore, in the development stage of parts, it is important to perform accurate vibration fatigue simulation and bench test verification on the parts. In such analyses and experiments, power spectral density random vibration signals are commonly employed as load inputs. Currently, the main approaches within the industry to acquire such load signals can be divided into two categories. First, a PSD load spectrum generated based on experience or a simplified model is provided depending on a whole vehicle factory. However, due to the complexity and dynamic coupling effect of the whole vehicle system, even a host factory is difficult to output a PSD signal capable of accurately reflecting the actual stress state of the parts under the actual complex road conditions. The method leads to deviation between the current simulation and test conditions and the actual working conditions, and can possibly cause misjudgment of design, prolong the development period and even bring potential fatigue risks to products. And secondly, directly acquiring acceleration time domain signals of mounting points of parts through a real vehicle road test. The method can acquire load data closest to the actual situation, but has obvious bottlenecks in engineering practice, namely, on one hand, the time length of signals required to be acquired is very long to cover enough roads and driving conditions, which directly contradicts with the development period of a tense project, and on the other hand, the acquired time-domain signals cannot be directly used as control signals to be input into a vibration test bed for vibration fatigue test in the frequency domain. Therefore, in engineering practice, a method for efficiently and accurately converting a long-term and real road test time domain signal into a PSD frequency domain load signal which not only maintains the frequency structure and fatigue damage characteristics of the original signal, but also is suitable for limited long-time test in a laboratory is needed. Disclosure of Invention In order to efficiently and accurately convert a long-time and real road test time domain signal into a PSD frequency domain load signal which not only maintains the frequency structure and fatigue damage characteristics of an original signal, but also is suitable for limited time test in a laboratory, the invention provides a random vibration test signal conversion method based on damage equivalence, which comprises the following steps: s1, acquiring time domain vibration signals of parts of a new energy automobile under various actual road conditions; s2, obtaining frequency domain impulse response corresponding to each frequency point by performing impulse response spectrum calculation on the time domain vibration signal; s3, calculating fatigue damage caused by vibration of each frequency point based on the frequency domain impact response, and generating a corresponding fatigue damage signal; s4, according to the cycle times of each actual road condition, obtaining a damage accumulation result representing total damage by accumulating fatigue damage signals; S5, determining a power spectrum density signal by iterative calculation by taking a damage accumulation result as an equivalent target, so that vibration fatigue damage generated by the power spectrum density signal within a preset test time is equal to the damage accumulation result; And S6, extracting the maximum value of the frequency domain impulse response under all road conditions as a maximum load envelope, converting the power spectrum density signal into transient response, and comparing the transient response with the maximum load envelope to verify the amplitude rationality of the power spectrum density signal. According to the invention, the long-time and complex actual road condition time domain vibration signals are efficiently converted into the short-time and frequency domain power spectrum density si