Research Of Lightweight Design For The Vehicle Door Structure Based On Stiffness And Crashworthiness

The lightweight design for vehicle body is the main way to improving fuel efficiency andreducing emissions in order to control the environmental pollution. As an importantcomponent of vehicle body, the vehicle door’s stiffness and crashworthiness performancehave a significant impact on the whole performance. The lightweight design of the vehicledoor is a complicated multi-parameter and multi-state design problem. Previous research ofthe vehicle door’s lightweight design is usually just based on single performance of the door,without considering both the stiffness and crashworthiness performance. Therefore, thelightweight design research of the vehicle door based on stiffness and crashworthiness hasimportant significance.This paper which is based on the plug-in hybrid electric vehicle research anddevelopment project of an enterprise, mainly reserched on the lightweight design for the frontdoor of the vehicle body structure. Firstly, the door’s calculated and experimental modal wasanalysised. Comparing the calculated modal result and experimental modal result. the reliablefinite element model of the door and the door’s modal performance were obtained. Withreference to the relevant standard of the enterprise, the door’s performance of vertical stiffness,sash lateral stiffness, inside and outside plate waist stiffness was analysised based on thefinite element model. With reference to the domestic and international car crash standards, thefinite element model of the door’s column crash was established. The door’s crashworthinessperformance was obtained by the column crash analysis. Considerring the analysis result ofthe vehicle door’s modal, stiffness and crashworthiness, the goals and constraints of thevehicle door’s multi-objective optimization were determined. Through the optimizationobjectives’ sensitivity analysis about the thickness of each component of, including weightand first-order modal frequency sensitivity analysis, the thickness of the first six keycomponents was selected as the design variables. Then the mathematical model of themulti-objective optimization was established. By using the uniform Latin square designmethod, the sample points were selected. Considering the characteristic of eachapproximation model, the second-order response surface model of the weight, the kriging model of the first-order modal, the kriging model of the stiffness and the kriging model of theinner panel’s maximum deformation along Y-direction in the door’s column crash wereestablished based on the approximation model method. The approximations’ accuracy wereverified, and the results met the engineering analysis requirement. Finally, the multi-objectiveoptimization problem were solved by using the genetic algorithm NSGA-Ⅱ, then thelightweight plan was selected and the solution was verified by using FEM simulation.The final lightweight plan showed that the door’s stiffness met the design requirement,the crashworthiness performance was not reduced, the first-order modal frequency of the doorwas34.3Hz, the mass of the door was17.79kg, the lightweight ratio reached2.73%comparedto the original door. Overall, this paper completed the research of the vehicle door lightweightdesign, and the entire design process had important reference significance on the lightweightdesign of other vehicle body components.