Research On Dynamic Performance And Multi-Objective Optimization Of Heavy Vehicles

With the continuous development of our national economy,the demand for the transportation capacity of road traffic is increasing day by day,the road construction technology and pavement smoothness have been improved,and the performance of truck has been improved accordingly.The relationship between vehicle ride comfort,handling stability and road friendliness has been paid much attention by researchers at home and abroad.However,most of them are the study of ride comfort or maneuvering stability,or the combination of one of them with the road.With the high speed and heavy traffic,the research that the vehicle performance and road friendliness are combined to improve the overall performance of heavy haul vehicles,and reduce the cost of road maintenance is an important subject worth discussing.It has important theoretical significance and engineering application value in highway transportation and automobile industry.The main purpose of this study is to realize the comprehensive optimization of the dynamic performance of heavy vehicles and get the best parameter matching through analysis of the factors influencing the smoothness,stability and road friendliness of heavy-duty vehicles by the technical route of theoretical modeling,numerical simulation and analysis,and experimental verification under the effect of random pavement excitation according to the dynamic performance of heavy-haul vehicle.The main research work is summarized as follows:Firstly,a semi-vehicle model and a vehicle model of three-axis heavy-load vehicle of three-axle heavy-duty vehicle are established based on the theory of multi-body system dynamics theory.A complete vehicle assembly test bed with a six-excitation head for a three-axle heavy vehicle is established through secondary development of multi-body system dynamic software Adams/car.Basted the test bed,a virtual simulation model of heavy vehicle is constructed.Through the analysis and comparison of the dynamics of the three models,two conclusions are obtained that the dynamics performance of the semi-vehicle model is applicable to the research of the whole vehicle model and the performance of the virtual simulation model is very close to that of the semi-vehicle model when the automobile runs on flat road.Secondly,a three-point virtual excitation model for three-axle heavy duty vehicle is established so that the ride comfort of the half-vehicle model is analyzed conveniently.Through the simulation analysis of the power spectral density of the factors related to the vehicle response,the influencing factors of the vertical acceleration root mean square of the cab seat and the influence factors of the weighted 95th percentile aggregate fourth power force,the common influence factors and the influence law of the vehicle ride comfort and road friendliness are pointed out.Thirdly,a smooth simulation experiment is carried out,acceleration response power spectral density of different parts of heavy vehicle are analyzed under different vehicle speed and load weight,The rationality and accuracy of the model are confirmed through the comparison of the simulation results and experimental results,calculation of the goodness of fit between the two results,and accuracy verification of smoothness model.Fourthly,the stability model of a vehicle with uniform turning speed is constructed.The factors influencing the stability factor of the evaluation index of steady-state response are discussed.An improved stability factor is obtained according to the redistribution of vertical load on the wheel caused by centrifugal force during turning and the dynamic load generated by random excitation on the road surface.The quantitative relationship between tire load and road friendliness is established.The influence of suspension parameters on the handling stability and road friendliness in the vehicle roll motion is analyzed.Finally,the train of thought and method to optimize the ride comfort,stability and road friendliness of heavy-duty vehicles are put forward.The evaluation index of ride comfort,stability and road friendliness is taken as the optimization objective,and the stiffness and damping of the front and rear suspension are taken as variable parameters.The optimization model of heavy-duty vehicle integrated with ADAMS/car module and Matlab module is established.The value of design variables is given in the range of constraints,and based on NSGA-? optimization method through improving Elite Strategy,the Pareto optimal solution of the design variable and the Pareto frontier of the optimization objective function are obtained by synthetically optimizing and analyzing the ride comfort,handling stability and road friendliness of the heavy-haul vehicle.The multi-objective optimization of heavy-haul vehicle dynamic performance is realized,and the experimental results are verified and analyzed.