| The research of automobile structure and material has been the focus and hot spot in the field of automobile.The continuous advancement of modern technology has driven the progress of processing technology,and aluminum alloy has begun to gradually replace steel.Aluminum alloy can achieve light weight of body while improving performance,and aluminum alloy material has less density and higher specific strength compared with steel,diversified ways of molding and strong shapability,so aluminum alloy is more and more applied to various body structure parts by die-casting integrated aluminum alloy structure instead of stamping-welding structure.Although the structure of automobile front hatch is relatively simple,the inner and outer plates,small parts and their processing technology are very complicated and tedious.This paper takes a car front hatch as the research object,based on the traditional punching-welding structure,according to the results of its topology and morphology optimization,combined with the die-casting process guidelines for a comprehensive study,the design of the front hatch with integrated inner and outer panels,and numerical simulation of die-casting molding,and then finally the optimization of the product for lightweight.(1)The front hatch of a conventional punch-welded structure of an automobile was selected as the research object,and a three-dimensional model was established by CATIA.The most commonly used die-casting material,Al Si10 Mn Mg aluminum alloy,was selected.For several common working conditions and constraints of the front hatch of the traditional punch-weld structure,topology optimization of the inner plate and shape optimization of the outer plate were carried out,and the position of the reinforcement was initially determined.Then the structure of the reinforcement was designed according to the design requirements of the die-casting process,and the integrated design of the front hatch was carried out.After the design was completed,the displacement and modal analysis of the integrated front hatch was carried out by Hypermesh under common operating conditions.The results show that the performance of the integrated front hatch can meet the requirements.(2)The solution design of the integrated front hatch for the pouring system and the overflow discharge system.Numerical simulation of velocity field,air roll phenomenon and shrinkage volume phenomenon were carried out by FLOW-3D software.Based on the calculation results,the orthogonal test was used to determine the simulation test arrangement for the die-casting process parameters.Based on the L934 orthogonal table,a four-factor,three-level orthogonal simulation test scheme was designed,and simulation calculations were performed for each scheme.Based on the roll-up volume and shrinkage volume as indicators,the test results were analyzed using the variance method to obtain the better die-casting process parameters for the product and verify the die-casting reliability of the integrated front hatch.(3)Based on the above analysis,the DOE experimental design of this front hatch was further carried out using the optimal Latin hypercube method with the optimization software ISIGHT.A second-order response surface approximation model based on common operating conditions is established to verify that the approximation model can continue the subsequent optimization design,and then a multi-island genetic algorithm is used to determine the optimal solution from the iterative results with weight and stiffness as the optimization objectives based on the approximation model.The front hatch model corresponding to the obtained optimal parameters is subjected to stiffness and modal calibration analysis,and the results show that it meets the operational requirements.Finally,the integrated front hatch was verified by die-casting simulation,and the product could be produced by die-casting.Compared with the punch-welded structure,the mass of the optimized integrated front hatch was reduced by 41%. |
PDF Full Text Request