Accuracy Evaluation And Analysis Of Load Spectrum Decomposition Of Vehicle Multi-body Simulation Based On Digital Pavement

The fatigue durability of automobile chassis parts is an important index to evaluate the safety and reliability of automobile.The application of CAE Technology in the rapid development,design and prediction of the fatigue life of parts is a hot issue in the current research.The load spectrum of automobile chassis components is the key element to analyze the fatigue,reliability and durability of components.However,the traditional method of extracting the load spectrum of component connection points by real vehicle road test signal combined with virtual iteration has the disadvantages of long research and development cycle and high cost,so the digital road simulation technology has developed rapidly.However,the digital road simulation technology is not mature enough,and the difference between the simulation accuracy of the virtual iteration method and that of the virtual iteration method has not been analyzed in detail.Based on this,this paper takes the steering knuckle of an SUV test vehicle as the research object,and comprehensively uses the finite element and multi-body dynamic analysis methods to evaluate the accuracy of the simulation load spectrum decomposition of the digital road vehicle.According to the requirements of the fatigue durability enhanced road test in Tongzhou test field,the whole vehicle signal collection and sensor layout scheme are designed,the vehicle enhanced road vibration response test is carried out,the real vehicle collected the strengthened road wheel center six component force,suspension and body key point monitoring signal,and the collected signal is tested and preprocessed to ensure the effectiveness of the signal and provide for the follow-up research Data base.Taking the knuckle as the research object,the finite element model is established and modal analysis and flexibility treatment are carried out.The free modal test of knuckle is carried out and compared with simulation,which proves the accuracy of the finite element modal analysis of knuckle.The rigid flexible coupling multi-body dynamic model of the whole vehicle with the flexible body of the knuckle is established,and the whole vehicle model and the tire model are verified successively through the indoor bench test.The relative errors of the RMS value of the six component force of the wheel center and the monitoring signal are all within 20%,and the error range of the tire model and the rigid flexible coupling model of the whole vehicle is demonstrated,as well as the applicability of the 3D digital road simulation.CRG(curved regular)based on the enhanced road elevation data acquired by laser scanner Grid)digital road model,3D digital road vehicle multi-body dynamics simulation and virtual iterative method Vehicle Multi-body dynamics simulation are carried out,and the simulation data and real vehicle test signal are analyzed and compared from the time-domain,frequency-domain,RMS value,pseudo damage ratio,wear level count and other data statistical aspects.At the same time,digital road and virtual iterative simulation data and test monitoring under different speed conditions are compared Signal.The results show that the simulation accuracy of the digital pavement method is slightly lower than that of the virtual iteration method,the maximum error is 28.01%,and the maximum error of the virtual iteration method is 22.61%.However,the overall trend of the monitoring signal in time domain and frequency domain is basically the same,the relative error of RMS value is within 30%,and the pseudo damage ratio is between 0.65 and 1.70,which can meet the accuracy requirements of the subsequent fatigue analysis.The modal displacement curve of the steering knuckle obtained from the multi-body simulation of the whole vehicle by the digital pavement method and the virtual iteration method is used to analyze the fatigue life of the steering knuckle by the modal stress recovery method,and the fatigue damage and life nephogram of the two simulation methods are obtained.The results show that the two methods have the fatigue vulnerable area at the lower end of the connection point between the shock absorber and the steering knuckle,and the relative error of the maximum damage value is 7.08%.It is proved that the error between the digital road method and the virtual iterative method simulation is small,which can effectively predict the fatigue life of the automobile chassis parts,and verify the accuracy of the load spectrum decomposition of the digital road method in the research and development of the whole vehicle or parts At the initial stage,the efficiency can be further improved and the cost can be reduced.