Studies On Load Characteristics And Structure Optimization Of Vehicle Suspension Control Arm

The control arm is an important part of the car suspension system,which connects the body and the wheel to transmit force and torque.The performance of the control arm has an important influence on the handling,confort and safety of the car.The main factor determining the performance of the control arm is the load input.Accurate load input can greatly improve the reliability of the design product and reduce the product development cycle.The traditional methods of obtaining the hard point load spectrum of the control arm by using the dynamic model are often affected by the accuracy of the dynamic model.Therefore,designing and implementing a scheme for directly acquiring the load spectrum on the control arm is of great significance for the design of control arm.This paper takes the front and lower control arm of a car as the research object,and carries out the following research work:The finite element model of the control arm is established.The finite element analysis of the control arm is carried out by pilling and crushing,then the analysis results are compared with the test results.The stiffness,modal and strength of the control arm are analyze and check to meet the design requirements.The control arm load spectrum acquisition tooling is designed,and the interference check and strength check are carried out.After the tooling is completed,the hard point positions of the tooling are checked.Strain gauges are attached to the ball pin of the control arm,and the strain gauges are composed of half bridges in the X direction and the Y direction,then the relationship between the X and Y bridges output and the load of the control arm ball joint are calibrated.According to the scheduled plan,the signal spectrums on the control arm under fatigue conditions are collected.The acquired signal spectrums are corrected to obtain the ball joint hard point load spectrums and the load spectrums of the front and rear bushing hard points,then the load spectrums ball joint hard point is pre-processed.The control arm fatigue test tooling is designed.The feasibility of the fatigue test tooling is proved by comparing the control arm damage distribution under the constraints of the test tooling and the design constrains.Based on the principle of damage equivalent,the load spectrum of the ball joint is equivalent to several load blocks.The damage distribution of the control arm loading the original load spectrums and the load blocks is compared,which proves the correctness of the damage equivalent result.Then the control arm sample fatigue test is carried out to verify the fatigue performance of the control arm sample.Optimizing the structural of the control arm by using the three boundary position and the thickness of the control arm as design variables.Comparing the sampling points distribution of Latin Hyoercube Sampling and Hammersley Sampling,the experimental design of Hammersley sampling with more uniform sampling points is selected.The proxy models are constructed by Kriging and RBF methods,and the accuracy of the two proxy models at sampling points and non-sampling points is compared.Finally,the mathematical model of control arm structure optimization is established,and the model is solved by genetic algorithm.The performance of the control arm is improved after optimization,and it still meets the design requirements.