Research On Editing Method Of Load Spectrum For Durability Analysis Of Automotive Chassis Parts

Load spectrum accelerated editing is an important part in component durability testing.The accuracy of component durability test results depends on the quality of load editing,but load spectrum editing methods are not unique,and the characteristics of acceleration spectrum obtained by different editing methods are different.In addition,the load editing quality is affected by the editing parameters,so the editing method and the editing parameters jointly affect the load editing quality.The editing of the load spectrum is still an important issue to be studied in depth.An accurate and efficient load spectrum editing scheme is of great significance to improve the durability test efficiency and quality of the parts.Based on the data collected from the test field,this paper uses the typical load editing method in time domain and frequency domain to obtain the acceleration spectrum,and compares and analyzes the acceleration spectrum from many aspects,and summarizes the characteristics of different editing methods.The experimental scheme of load spectrum acquisition is designed to collect the six component force load of wheel center and the strain signal of steering knuckle under different road conditions in the test site.The power spectral density of the original load is analyzed.According to the results of the power spectral density analysis,the low pass filter frequency is 50 Hz,while the singular value and data drift are removed,and 256 Hz resampling is selected based on pseudo damage equivalence with original load spectrum.The preprocessing before load editing is completed,which provides the data base for accelerated load spectrum editing.Based on the six component force load and the strain signal of steering knuckle,the accelerated six component force spectrum is obtained by damage retention editing method,pseudo damage retention editing method and peak-valley extraction method,and principle of editing method is clarified.The accelerated spectrum is compared and evaluated from the aspects of time compression,power spectral density,level crossing count,rain flow count and statistical parameters.The difference of the accelerated spectrum is studied,and the characteristics of editing method are summarized and analyzed.Wavelet transform editing and damage retention editing were used to obtain the acceleration spectra of six component force load of wheel center with different damage retention ratios.The influence of editing method and damage retention ratio on the quality of acquisition acceleration spectra was studied.To solve the problem that wavelet transform is difficult to determine the decomposition function and the number of decomposition layers.Based on the basic theory of S transform,the application of S transform analysis in the field of load spectrum accelerated editing is explored.The maximum amplitude spectrum is extracted by S transform analysis of the strain signal,and based on this,the damage load in the six component force signal of wheel center is identified to obtain the acceleration spectrum,and the S transform acceleration spectrum is compared with the damage retention acceleration spectrum to verify the applicability of the S transform editing method.The results show that the maximum value spectrum extracted by S transform editing method can accurately identify the damage load in the original load,S transform editing method is the most efficient load editing scheme in all editing methods.The finite element model is established,the time domain acceleration spectrum and the frequency domain acceleration spectrum are used as the excitation load respectively,and the nominal stress method is used to simulate the fatigue life of the steering knuckle.From the aspect of fatigue simulation,the accuracy and efficiency of the fatigue problem analysis of parts by different acceleration editing methods are further discussed.meanwhile,by the fatigue simulation of the S transform acceleration spectrum,the rationality of the S transform editing method applied to the accelerated editing of durability load of components is further verified.Analysis shows that S transform editing method can maximize the efficiency of fatigue analysis under the premise of ensuring the accuracy of fatigue analysis.This method has contribution to improving the quality of load editing and enriching the load spectrum editing method,and provides a reference for the accelerated editing of fatigue durability loads of auto parts.