Research On The Interface Profile Modification Of A Steering Kingpin Thrust Bearing Based On Optimal Contact Pressure Distribution

Kingpin thrust bearing is an important part of automobile steering bridge.The stand and fall of its working performance affect the safety and stability of vehicle seriously.Under the bidirectional of body load force and the wheel supporting force,the bearing is always in the condition of eccentric compression,which easily leads to the tendency of fatigue failure on the side of eccentric load.Research shows that the overbalance of contact pressure distribution is an important factor caused fatigue failure.By means of trace modification on the interface,the strength and life of the bearing can be enhanced effectively.So doing a study on the method of modifying the joint surface of elastic structure,and generating applied research on the steering axle.It has vital significance to solving the problem of elastic contact modification.The traditional modification design Lundberg logarithmic curve based is unable to adjust the jointing surface modification under complex conditions.It has high computational complexity when conducting repeated iteration with finite element software,and need a large amount of calculation.Besides,the semi-empirical method,which uses contact deformation to estimate the modification amount,it can't obtain effective optimization results as well.Aiming at the shortcomings of the modification design using traditional method,a new modification method of interface is put forward in this paper.The main research work is as follows:(1)The solution research is conducted for the optimal contact pressure distribution model.Based on the mathematical programming theory and under the condition of satisfying the force balance and deformation coordination,two solving models are established for solving the optimal contact pressure distribution on interface——Least square solution model and Minimax solution model.What's more,examples are used to verify the effectiveness of optimal solving model.(2)The new method research is conducted for elastic contact modification.The coupling stiffness calculation ideology is proposed based on the basic principle of finite element method,which considers the interaction between the shape and the contact pressures.An efficient and accurate modification calculation method is put forward to centralizing solving the contact stiffness matrix.The excellent modification result can be obtained with only one structural analysis.In view of the over determined boundary structure,on the basis of considering the effect of contact characteristic parameters and displacement boundary condition on the modification area of interface,the mathematical solving model based on the optimization method of Minimax,which make it a reality to achieve perfect modification with low-order linear calculation merely for the optimization problem on the interface.(3)The new method modification research is conducted on interface of Kingpin thrust bearings.By means of appropriate simplification for axle model,the modification of kingpin thrust bearing is converted to nonlinear contact modification containing a kind of over determined boundary conditions.Consider that the nonlinear influence caused by multi-domain contact conditions when carrying contact modification on interface,the modification optimization problem on the interface of bearing is translated into low-order mathematical programming problem,and then achieve the optimal modification.The comparative analysis of the examples is conducted for contact model of kingpin thrust bearing.Analysis results show that the interface modification algorithm based optimal contact pressure distribution has the feature of high precision and high efficiency,which provides a new solution for solving the problem of bearing failure and also can be applied to the general modification solution of elastic contact problem effectively.