Lightweight Design of Car Doors Based on Six Sigma Reliability Optimization

Considering the impact of machining errors in the mass production of car doors, uncertainty factor analysis is introduced to achieve the three-in-one optimization goal of “lightweight-performance-reliability”. This paper takes a car door as the research object. First, its finite element model is established, and analyses of upper torsion, lower torsion, vertical, and belt line stiffness working conditions, as well as modal analysis, are carried out to obtain the door’s stiffness and modal performance data. Taking the thickness of the door sheet metal parts as the design variable, an RBF surrogate model is established. The NSGA-II algorithm is used to carry out reliability optimization with the stiffness under four working conditions, the first-order torsional mode, and the Six Sigma reliability level as constraints, and with the minimization of door mass and maximization of the first-order bending mode as objectives. The research results show that while meeting the reliability requirements and achieving weight reduction of the door, the performance of the door is also improved.