Decoupling Mode-based Shape Optimization For Vehicle Door In The Conceptual Design Stage

With the development of society and economy, the competition of automobilemarket is becoming fiercer and fiercer, and this requires that the development cycle ofnew autos should be as short as possible. As we know, the door is a very importantpart of the vehicle body, therefore, the door’s properties, such as stiffness, strengthand vibration, etc, must be calculated and analyzed during the concept design phase,and the preliminary optimization scheme should be put forward, which has a greatsignificance for shortening the developing cycle and enhancing the productivity.Though the application of approximate model technology is mature in theproblems of engineering optimization, the number of samples used to build model isbecoming much bigger with the in-depth research of optimization problems and theincrease of design variables. How to balance the model’s precision and efficiency hasbeen the bottleneck in the field of engineering optimization.By using the approximate model technology, the section shapes of door areoptimized during the stage of conceptual design in this paper. The research contentsare as follows:(1)Calculating the initial parameters of the door：The finite element model of theoriginal door is established, both the door’s stiffness and free model performance areanalyzed.(2)Setting the shape variables and calculating the sensitivity: Based on thestructural feature of the door, the shape variables of the main sections are defined byusing HyperMorph, and the problems which shape changes may lead to are discussed.Then the sensitivity of the shape variables is calculated and the final optimal designvariables are obtained by sifting through all the variables.(3)Recognizing the coupling relationship between variables and building theapproximate model: The sample points are generated based on Cut-HDMR, and theDOE experiment is defined. Then the response values of sample points are calculatedin order to judge the coupling between the optimal design variables. By using theinterpolation method of Kriging, every term of the Cut-HDMR is established so as tobuild the approximate model of static stiffness, and then the model’s precision istested. (4)The multi-objective optimization model of the door’s stiffness is established,and the balanced objective function is built, then the model is optimized by NSGA-II.The results show that the vertical stiffness and torsional stiffness are raised greatlyand the distribution of stiffness is more balanced, and the quality of the door islightened reasonably.