Research On Bench Equivalent Test Load Spectrum Of Chassis Parts Of A Passenger Car Based On Actual Road

With the rapid development of automobile industry,the development of vehicle products in China is gradually changing from learning imitation to independent research and development.In the increasingly competitive market environment,manufacturers need to speed up the pace of listing new cars.Fatigue durability is one of the main design indexes of vehicles and its parts.There are three ways of vehicle fatigue durability test,including virtual test,indoor bench test and actual road test.There are some problems in actual road test,such as long cycle and high cost,and it is impossible to predict fatigue life in the early stage of vehicle research and development.Both indoor bench test and virtual test technology need to provide accurate load data input,otherwise,no reliable prediction data can be obtained.In this paper,on the basis of the actual road,the load spectrum of the bench test was compiled by using the technology of the virtual test ground,taking a passenger vehicle’s sub-frame as an example.First of all,according to "the standard of driving test for the stereotyped reliability of passenger car and micro-vehicle products".Referring to the road surface condition of reliability test in a certain vehicle test field,the virtual road modeling was carried out with the road editor of Adams,and the virtual test ground was built which can better reproduce road surface of the road test.Then,the finite element analysis of the sub-frame was carried out by using the finite element software Hypermesh and the modal neutral file was generated.The accuracy of the finite element model was verified by the stress-strain test.And the parametric modeling method was used to establish the vehicle model quickly in Adams/Car,and the rigid sub-frame was replaced with the flexible body to establish the rigid and flexible coupling model of the vehicle.The rigid and flexible coupling model of the whole vehicle was used to carry out the vehicle virtual test on the established virtual test field.Then,the load time history of key hard points was extracted to provide accurate load data for the subsequent compilation of load spectrum.Finally,the load spectrum of the sub-frame was transformed into the corresponding stress spectrum by the bench calibration test.and the load spectrum was analyzed statistically by the double parameter rain flow counting method,the range is Weibull distribution and the mean is normal distribution.The fatigue damage equivalent principle was used to establish the 8-stage program load spectrum,and the load spectrum was compressed by deleting low load method.The final one-dimensional program load spectrum retains 99.84% damage and its length is reduced to 1/16 of the original load spectrum.In this paper,a complete set of equivalent load spectrum programming process for chassis parts of passenger vehicles was presented,which is suitable for the early research and development stage of vehicle.The proposed method of compiling load spectrum can be used as a reference for structural life prediction and bench test of chassis parts of other vehicles,which has certain theoretical reference value and practical significance in engineering.