Design And Performance Analysis Of A Light Bus With Variable Stiffness Suspension

With the rapid development of economy,people are demanding higher and higher performance of automobile.Suspension,as an important part of automobile,has a great relationship with the stability and ride comfort of automobile.Based on the schoolenterprise cooperation project,this paper will focus on suspension design,K&C characteristic analysis,vehicle handling stability analysis and ride comfort analysis.The aim of the paper is to match the suspension system of a light bus,to achieve lightweight suspension,and to improve the stability and comfort of the vehicle.For this reason,the paper improves the six-leaf spring suspension of the original vehicle and adopts a new type of leaf spring with few leafs and variable cross-section.In order to meet the design requirements of variable stiffness suspension,the structure of main spring and auxiliary spring is adopted.1、Firstly,from the point of material mechanics,the paper expounds the theory of bending-deformation and derives the calculus equation of bending-deformation.Then,the paper introduces two hypotheses of leaf spring,common curvature method and concentrated load method.And the paper introduces the rigidity calculation method of parabolic leaf spring and trapezoidal leaf spring.Finally,the rigidity design theory of leaf spring is put forward by using calculus theory and Matlab programming.2 、 Based on the design requirement of suspension,the paper redesigns the parabolic-spring,the structure is main spring and auxiliary spring,the main spring stiffness is 90N/mm,and the total stiffness is 135N/mm.According to the stiffness theory,the structural parameters and arc height of the main and auxiliary spring are designed.Then,the limit stress check and finite element strength check of the parabolicspring are carried out,and the lightweight analysis of the improved parabolic-spring is carried out.For the matching of dampers,the damping coefficients are checked in a reasonable design range.For the stiffness matching of the stabilizer rod,the diameter of the stabilizer rod in this paper is 18 mm,and the roll angle stiffness is calculated in a reasonable design range.3、The paper introduces the K&C characteristic of suspension,K characteristic refers to geometric kinematics characteristic,C characteristic refers to elastic kinematics characteristic.In the paper,ADAMS is used to build the front suspension model,and the simulation of coaxial wheel hopping,reverse wheel hopping,longitudinal loading and lateral loading is carried out.The change of wheel alignment parameters is analyzed.The front wheel toe angle,front wheel camber angle,kingpin caster angle and kingpin camber angle are all within a reasonable range.The roll stiffness,the height of roll center,the change of wheelbase and the change of wheelbase are also analyzed.Similarly,ADAMS is used to build the rear suspension model,and the K&C characteristics of the rear suspension in the paper are analyzed.4、In the paper,the front suspension model,rear suspension model,tire model,power system,brake system and body are established by ADAMS,and the whole vehicle model is established.Then,the vehicle ride stability simulation and vehicle ride comfort simulation are carried out.The vehicle ride stability simulation includes steady-state steering simulation and snake-shaped pile-winding simulation.The vehicle ride comfort simulation includes impulse road surface simulation and random road surface simulation.Based on vehicle simulation,the front and rear suspension parameters are optimized,and the optimized effect is verified by vehicle test.After optimization,the scores of steady-state steering test and snake-shaped pile-winding test are improved.After optimization,the maximum value of Z-direction acceleration of impulse road surface test decreases,and the RMS value of Z-direction acceleration of random road surface test decreases.Finally,the experiment proves that the performance of suspension is improved obviously after the optimization of suspension parameters.