Structural Analysis And Optimization Of Suspension And Steering System For Vehicle Handling Stability And Ride Comfort

This paper analyzes and optimizes the suspension and steering system by combining theory with simulation.Suspension and steering system are studied and optimized based on considerations of handling stability and ride comfort of the vehicle.In theoretical terms,explanations are given for the impacts of suspension and steering systems on the performance of vehicle.A vehicle simulation model is built with the multi-body dynamics software.Through simulations in typical working conditions,the influence of the key structural parameters on the performance of the vehicle is emphasized.On this basis,the analysis variables are used as optimization variables and the evaluation indexes are used as optimization objectives to carry out deterministic and robust optimization,which ultimately leads to an improvement in vehicle handling stability and ride comfort.Firstly,the theory of vehicle lateral and vertical dynamics is presented.The kinematics and comprehensive stiffness of the steering system are explained.Through parametric models,the connection between the suspension,the steering system in relation to the dynamic characteristics of the whole vehicle is described.Next,a simulation study is carried out to assess the impact of the suspension and steering structure on the vehicle’s handling and ride comfort.Adams/Car software is employed for developing the vehicle simulation model.The Constant Radius Cornering and Swept-Sine Steering Input are used as typical working conditions of handling stability.The ride comfort on a random road and on a pulsed road are used as typical working conditions of ride comfort.As part of a simulation study of the structural parameters of the steering system,the impact of the initial and phase angles on the kinematics of the steering system is emphasized.In addition,the impact of the initial and phase angles,as well as torsion bar stiffness,on the vehicle’s handling stability is investigated.The suspension bushing stiffness,spring stiffness,and shock absorber damping are all taken into account in the simulation analysis of the suspension structure characteristics.The sensitivity analysis is carried out to obtain the sensitivity index of the suspension parameters to the objective evaluation index of the vehicle performance in typical working conditions.The parameters with a sensitivity index greater than 10% are selected for simulation analysis.The simulation study shows that the initial angle and phase angle play an influential role in the kinematic characteristics of the steering system.The initial angle mainly influences the symmetry of the steering ratio.The phase angle mainly influences the fluctuation of the steering ratio.By varying the initial angle and phase angle from 0° to 360°,the performance evaluation indexes of the vehicle under typical handling stability conditions show a trend of 180° with the initial angle and phase angle.The stiffness of the steering torsion bars has a significant influence on the evaluation indexes,and the trend of its influence on each indexes differs.The parameters of the suspension have a definite influence on the evaluation indexes.The same structural parameter does not have the same sensitivity index for different indexes.Finally,With the RBF neural network model,the correlation between the optimization variables and the optimization objective is fitted.The suspension and steering system structure is deterministic and robustly optimized with vehicle handling stability and ride comfort in mind.In the deterministic optimization,the evaluation indexes of each working condition are used as the optimization objectives.In robustness optimization,the mean and variance of each evaluation index are taken as the optimization objectives.The RBF model is solved using the NSGA-II algorithm.The Pareto front is eventually obtained.The optimization results show that the RBF agent model can be used to optimize the suspension and steering structure effectively.The optimized vehicle’s performance assessment indexes are enhanced under typical handling stability and ride comfort simulation conditions.The objective function of the deterministic optimization solution is better than that of the robust optimization solution,but the robustness of the robust optimization solution is significantly better than that of the deterministic optimization solution.