The Vehicle Gear-box Transient Dynamics Research Including Bearing Power Transmission

China has manufactured and sold the most vehicles all over the world since2009,the automotive industry has been a mainstay in the Chinese economy, so thedevelopment of automotive technology is the vital factor that effects the quality ofChinese automotive industry. The gear-box, as an important part of vehicle, is becomingmore accuracy, more completed and lighter. We usually use the finite elementsimulation to test the gear-box’s performance.In the theoretical part, this thesis used Hertz Contact Theory to analysis thebearing’s stress condition, computed the oil film thickness in the ball bearing.According to the practical working condition, combined the elastic deformationbetween the roller and rings and the oil film deformation, created a simplified bearingmodel which suit vehicle gear-box, then used explicit dynamics software LS-DYNA tocalculate the gear-box model, discussed the analysis results. The major work in thisarticle concludes:Firstly, this thesis introduced the background and the current situation of thebearing simulation, also introduced the research method. The Hertz Contact Theory isused to analysis the bearing’s static force, the stress condition in it is deduced. So thisthesis introduced the friction force and friction moment equations in the bearing tomake up the deficiency of Hertz Contact Theory in the bearing stress analysis.Secondly, considering the characteristics of the cylindrical roller bearing in theMF524gear-box and the theory ‘the deformation in the bearing is gathered by thedeformation of rollers and the deformation of oil film’, this paper found the theoreticalbasis about how to calculate the roller bearing’s stiffness and then deduced thecomputational process. It pointed out that the roller bearing’s stiffness is a series ofcontact stiffness and oil film stiffness.Thirdly, according to the mechanical model of bearing, the purpose of this researchand the mock-up, this paper built the gear shafts’ finite element model, then built agear-box’ finite element model with simplified bearings. In this part, it also defined thematerial parameters, contact types, loads and constrains, prepared for the result analysis.At last, this dissertation used LS-DYNA to carry out an explicit dynamics analysisof MF524gear-box. According to the diagrams of gear-box’s stress distribution, thispaper analyzed the reason of the maximum stress’s appearance, then surveyed the variation of stresses. The results indicated that the method of simplified bearingsimulation could effectively transfer the forces from gear shaft to shaft block, but itshould consider the influence of the model errors.