Analysis And Optimization Of K&C Characteristics Based On A Mini Electric Vehicle Of Front And Rear Suspension

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.It is paid more and more attention in the development and design of modern automobile chassis.The K&C characteristics of the suspension depend on a large extent to the location of the geometric hard points and the stiffness characteristics of the flexible bushings.So,this paper,which is based on an electric vehicle company chassis development project,uses the multi-body dynamics ADAMS/Car to establish the front and rear suspension system model,carries on the K&C characteristics simulation and the test analysis,and 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 analyzes the performance evaluation of the suspension K&C characteristics and its influence on the performance of the vehicle from the theoretical level,and describes the test methods of studying the K&C characteristics of the suspension and the theoretical characteristics of the multi-body dynamics simulation.Secondly,according to the suspension structure of the electric vehicle,the front Macpherson and Rear trailing-arm independent suspension virtual prototype models are built by the multi-body dynamics software ADAMS/Car.Then the K&C characteristics simulation analyses of the suspension system are carried out,including the parallel wheel jump,opposite wheel jump,longitudinal force loading,lateral force loading and aligning torque loading.Compared with the mule car’s K&C bench test results,the accuracy of the virtual prototype model is verified,and the existing problems of K&C evaluation characteristic targets in the prototype are also found.Then,aiming at the difference of K&C characteristic targets of design vehicle suspension,an objective function is established.Then 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.Sensitivityanalysis of target characteristics with hard points and bushings stiffness is carried out to find the greatest influence variable factors on K and C target characteristics under the multi working conditions.Refer to the basic theory and empirical database of K&C,use the genetic algorithm NSGA-Ⅱ 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,according to the configuration parameters of the full electric vehicle and make the necessary simplification,the virtual prototype model of the vehicle before and after the optimization is established by the multi-body dynamics software ADAMS/Car.According to the national vehicle stability test method standard,the vehicle simulation analysis is carried out under three conditions of steady-state rotation,steering angle step and slope braking.The vehicle’s steering characteristic,pitch characteristic,roll characteristic and yaw characteristic are analyzed.Comparison of the evaluation indicators show that the vehicle handling performance is better improved.