| Lighting structural weight in order to save on materials and energies in running is one of the contemporary automobile advanced manufacture technology development tendencies. Coming into the new century, sequentially boosting the automobile lightweight to reduce the oil consumes is still the important task for automobile industry facing therigorous challenge of the problems of resources and environment. To realize the automobile lightweight, the development tendency of the important parts' production is utilizing the hydroforming craft; the unimportant pats' production is using plastic or light metal materials to reduce the parts' weight. In this paper, on the wildly collecting the domestic and oversea research materials on hydroforming, the present situation and progression of study on hydroforming for rear axle housing are reviewed. Then the main research work of thesis is proposed. The following research has been done: Read a lot of domestic and oversea research materials on hydroforming for rear axle housing, realize the current production craft of light automobile rear axle housing and the advanced feature of hydroforming craft, determine the feasibility of finite element analysis for the hydroforming for rear axle housing and select the suitable finite element analysis software LS-DYNA to process simulation analysis. By using non-linear finite element theory, a non-linear finite element model for hydroforming for rear axle housing is established. According to the characteristic of hydroforming for rear axle housing, rigid-plastic material model is elected as tube blank material model process simulation analysis. Basic mathematics theoretical acknowledge of related finite element analysis, mechanical acknowledge, non-linear material constitutive relationship and solution for rigid-plastic finite element are discussed. Based on comprehending the detail hydroforming process for real axle housing, some technical details and computation control methods on the model building of hydroforming system for real axle housing, such as some necessary simplification to finite element model, the demarcation of the mesh, the method of loading the force, selection of element type and material constitutive relationship, ascertaining suitable friction coefficient, reduction integral and hourglass control, defining the solving time and so on, are researched deeply, in order to improve calculation speed and accuracy. Large quantity simulation analyses about some factors, which influence the hydroforming for real axle housing, such as bulge ratio, route of loading force, friction coefficient and tube blank characteristics, are operated separately with the dynamic explicit finite element analysis software LS-DYNA. The simulation results shows that when the hydroforming for real axle housing needs two bulge processes and the specific value of the two bulge ratio is about 1, the result is the best one; To obtain an appropriate route of loading force need adjust internal pressure and axial compression force for many times and according to the failure, the size of the two forces which has been mentioned can be rapidly and rationally adjusted; Because of good greasing conditions influencing largely, reducing the friction between tube blank and die inside surface as well as possibly not only makes more materials flow into the bulge area but effectively diminishes the axial compression force; The good or bad characteristics of tube blank material is also one of the decisive factors and when material is selected, we first consider its' formability. Comparing simulation results to the experiment data, in the same condition of the identical specific value, the relative error of the minimum thickness is less than 10%; The relative error of shrinkage mass along the axle direction is less than 9%; The relative error of maximum internal pressure is less than 10% and the simulative and experimental time histories of loading internal pressure have the same tendency of change; The relative error of maximum axi... |
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