Research On Lightweight Design And Forming Of Sub-frame Based On Investment Casting

With the development of automotive technology,lightweight research has become a hotspot in the industry.The sub-frame is an important part of the chassis of the car.Lightweight can not only reduce the quality of the car but also have a greater impact on the stability and comfort of the car.In this paper,the sub-frame of a certain model is based on investment casting technology,which uses aluminum alloy material instead of original steel material to carry out the material structure integration design of the sub-frame,and completes the lightweight design of the sub-frame.The main research contents are as follows:Firstly,the rigid-flexible sub-frame-front suspension multi-body dynamics model is established,and the dynamics simulation under five typical conditions is carried out.The load of the key hard point of the sub-frame is extracted,which is the finite element analysis and topology.Optimized to provide load information;at the same time,the finite element model of the sub-frame was established,structural strength and modal analysis were carried out,and the sub-frame modal test was completed.The accuracy of the model was verified by comparing the experimental results with the simulation results.Secondly,the multi-objective topology optimization theory and method are deeply studied.Based on the compromise planning method,the mathematical models of static multi-stiffness,dynamic natural frequency and comprehensive working conditions are established respectively.The weight coefficient of each working condition is calculated by orthogonal test method.Optimize to make the results more reasonable.Using Optistruct to realize sub-frame topology optimization under multiple working conditions,combined with topology optimization results and precision casting process requirements,the redesign of aluminum alloy sub-frame structure was carried out,and the thickness of each component of aluminum alloy sub-frame was taken as a variable.The size is optimized to determine the final structure of the sub-frame.At the same time,the finite element analysis of the new structure was carried out to verify the rationality of the new structure.Finally,the design of the gating system was carried out according to the structural characteristics of the sub-frame,and the casting simulation was carried out using ProCAST software to analyze the filling,cooling solidification and casting defects in the casting process.The results show that the obtained castings have fewer defects,the designed runner form and casting parameters are reasonable,and the casting performance is superior.The quality of the investment casting aluminum alloy sub-frame designed in this paper is 8.25 kg,the original steel sub-frame is 12.05 kg,and the weight reduction rate is 32%,and the stiffness and modal performance of the sub-frame are also improved,which indicates that the analysis and design method proposed in this paper is fully effective.The integrated design of cast aluminum material provides an idea.