| Suspension system is one of the important components of automobile chassis,and its K&C characteristics directly affect the vehicle's handling stability,ride comfort and braking performance.How to optimize suspension parameters in the term of vehicle performance is the key point of Suspension design.So,this paper,which is based on an vehicle company chassis development project,optimize its influence parameter geometric hard points and the flexible bushing stiffness,in order to ensure a reasonable suspension of the K&C characteristics,and obtain a good vehicle driving performance.First of all,this paper overviewed the content of suspension kinematics and Elastic kinematics,and intorduced the research method of suspension,which was consist of the characteristics simulation and the test analysis.With the suspension K&C characteristics test bench,the suspension K&C performanch test result datas of the standard car's rear suspension,which can be the target for the Later research.Secondly,from the theoretical point of view,this paper established the mathematic model of the multi-link independent suspension based on the rigid body kinematics,and solved the kinematics curve of wheel alignment parameters in the Matlab,and the influence of hard point coordinate on the suspension k characteristic is analyzed.Then the elastic kinematics mathematical model of independent suspension is established by considering the rubber bushing performance,and the influence of the rigidity of the bushing on the C characteristic of the suspension is analyzed.Then the elastic kinematics mathematical model of independent suspension is established by considering the rubber bushing performance,and the influence of the rigidity of the bushing on the C characteristic of the suspension is analyzed.Then the elastic kinematics mathematical model of independent suspension is established by considering the rubber bushing performance,and the influence of the rigidity of the bushing on the C characteristic of the suspension is analyzed.Then,model of the five-link suspension is established by Adams,which verifies the accuracy of the mathematical model.Compared results of the multi-body dynamics simulation with the mule car's K&C bench test results,and obtain the existing problems of K&C evaluation characteristic targets in the prototype,which can be established for objective function.And the use the multi-subject and multi-objective optimization software Isight and multi-body dynamic software Adams/Car,Matlab to build joint simulation and optimization platform.Sensitivity analysis of target characteristics with hard points and bushings stiffness is carried out to find the greatest influence variable factors on K&C target characteristics under the multi working conditions.Refer to the basic theory and empirical database of K&C,use the genetic algorithm NSGA-? to optimize the K&C characteristics of the prototype.The K&C characteristics of the prototype are improved in the reasonable design range.At the same time,this process provides a method and basis for the design of K&C characteristics of the suspension.Finally,Established the virtual prototype model of vehicle before and after optimized for dynamic simulation by the multi-body dynamics software Adams/Car.Angle gradients of steering,roll and pitch were analyzed in vehicle stability simulations,so were the maximum lateral accelerations.Characteristics of the understeering and pitch angle had different degrees of modifications after been optimized.Research shows that mathematic model of the multi-link independent suspension,methods of modeling by Adams/Car and optimization for suspension are reasonable and effective.With these methods,the suspension performance could reach the design goals after being optimized.This paper has positive reference meanings to the research and design of suspensions. |
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