Fatigue Durability Analysis Of Commercial Vehicle Body Based On Virtual Proving Ground

Commercial vehicles are widely used in the transportation industry due to their large load capacity and long driving distance,and the fatigue durability of vehicles directly determines its serviceable life cycle.In view of this,the major automotive companies are committed to improving the fatigue durability as much as possible in the vehicle development process,thus increasing the service life.The premise of extending the service life of the vehicle is to predict the parts where fatigue failure may occur,and then strengthen the design for the failure parts.Taking a domestic commercial vehicle as the research object,this dissertation proposes a new fatigue durability analysis method.By correlating the user cycle mileage with the road’s spectrum of the proving ground,combining the test site testing technology,the whole vehicle multi-body dynamics model and the fatigue durability simulation technology,the dissertation aims to make fatigue life prediction for vehicle development and guide the vehicle design.The details of the work are as follows:(1)Load spectrum acquisition and pre-processing based on user cycle mileage and proving ground road spectrum correlation results.Based on the damage equivalence theory,the correlation program between the vehicle 10000 km of vehicle users and the road’s spectrum of the proving ground is established,and the correlation results of the user proving ground are obtained.According to the load spectrum collection standard of proving ground,the sensor is installed and debugged on the selected sample vehicle.After the debugging is completed,the data is collected to ensure that there are three sets of valid data for each road load spectrum.Because there are excessive road section excitation signals when collecting data,the collected data should be cut by characteristic road section signals,and the best group of data should be selected among the three groups of data based on the Rossow sampling method.At the same time,in order to eliminate the interference in the process of load spectrum acquisition,abnormal signal processing is carried out on the collected signals,and the measured load spectrum is finally obtained for subsequent benchmarking.(2)The whole vehicle model is built and calibrated according to the sample vehicle parameters.According to the actual vehicle test data,such as the hard point coordinates,mass,inertia parameters of each component,the steering system,front and rear suspension system,flexible body frame,Ftire tire model,cab model and powertrain are established based on ADAMS/Car software.According to the connection state of the real vehicle,the models of each system are assembled and constraints are established,and the assembled multi-body dynamics model of the whole vehicle is checked and calibrated.This includes checking and confirming the hard point information,mass and inertia parameters of the model.Simulating and checking the steering power,front,middle and rear axles of the model as well as the mass of the whole vehicle.(3)Extracting load spectrum based on virtual simulation model for fatigue durability analysis.The method of 3D scanning pavement is selected to establish the virtual proving ground(VPG)based on the pavement roughness theory.In ADAMS/Car software,the virtual simulation model is built by using the whole vehicle multi-body dynamics model,the VPG and the virtual simulation control file to extract the simulation load spectrum,and it is compared with the measured load spectrum for verification.Based on Hypermesh,a finite element model of the cab is established and the inertial release method is used to obtain the stress field distribution results that can be used for fatigue simulation.The fatigue simulation process is built in n Code software based on the local stress strain method by combining the fatigue characteristic curves of the sheet metal parts and the load spectra obtained from the virtual simulation.Finally,compare and verify the simulation results with the experimental results,and predict the fatigue life of the frame.