Finite Element Analysis And Optimal Design For Interference Of Automobile Ball Joint

Ball joint is an important auto part of the car chassis system,which connects other parts in the car chassis system and has a direct influence on the handling stability,comfort and driving safety of the car steering.Therefore,in order to improve the quality of the ball joint,the ball joint in-depth study is necessary.Products have the problem of discrete frictional moments because of the unreasonable dimensional tolerance of ball joint and the shrinkage of the inner surface of ball race.In order to ensure the stability of the friction torque of ball joint and improve the production efficiency,it is necessary to optimize the performance of ball joint.The main contents are as follows:The more stable the torque of the same batch of products,the more reliable the quality of products.This paper firstly optimizes the process parameters of the ball race,and performs numerical analysis in the Moldflow software based on the orthogonal test.Using the process parameters determined by orthogonal testing can reduce the average volumetric shrinkage of the ball race compared to products molded in the previous injection molding process,thereby improving the torque stability of ball joints.Then,we should determine the best interference of ball joint.First of all,the torque model of ball joint is established according to the spherical conformal contact model,which is verified by the finite element analysis method.On the one hand,the true stress-true strain curve is obtained by the uniaxial tensile test of POM material,which is input in the finite element analysis.On the other hand,the relationship between contact pressure and friction coefficient is obtained by pin-disk friction test.We can set the minimum torque as the optimization target,and the average minimum contact gap is set as the evaluation parameter in the process of optimizing the interference.The relationship between the contact pressure and the friction coefficient and the theoretical model are used to determine the optimal interference combination,which is confirmed by the IAMT torque test.In addition,due to temperature have a lot of influence on the mechanical properties of the POM material,the stress-strain curves at 23? and 80? were measured by the compression test.The uniformity of the contact stress distribution of ball race is taken as the evaluation parameter,and the mean value of the contact stress is greater than the minimum contact stress value and as possible as close to the value.We re-optimized the radial and axial interference of ball joint,which is used to verify the analysis result under different heat treatment conditions by the ball joint torque test.The error between experiment results and the corresponding theoretical value were quantitatively analyzed by the data comparison.The optimization of the design parameters of ball race and the determination of the optimal interference of ball joint greatly improve the stability of the friction torque of ball joint.The conclusion of this study provides guidance for the further optimization of the performance of other ball joints,and provides reference for the study of other suspension parts.