Research On Bending Characteristics Of Front Rail In Concept Design Stage

The collision energy is most absorbed by the front rail during the front impact. Thestructure design quality of front rail plays an important role in the safety of the vehiclecollision. Under vehicle impact two deformable form of front rail are axial crushing andbending collapse. Plastic hinge is developed in bending collapse, which leads to a greatdeformation but energy is absorbed rarely. A research on bending collapse behaviour offront rail for controling it when vehicle front impact is therefore significant.Concept design is the most important stage in the vehicle design process, many vehicleparameters which determine the detailed design are determined at this stage. The researchon bending characteristics of front rail in concept design stage is very important for detaileddesign of front rail structure and improve the crashworthiness of vehicles. This thesissupported by Science and Technology Development Plan of Jilin Province (No.20126001)and its assorted project, FAW Group Combined Action Plan (1322A issue)，baseon the research of National Natural Science Foundation of China (No.50975121) andScience and Technology Development Plan of Jilin Province (No.20096004). The bendingcharacteristics of front rail in concept design stage were studied.This thesis describes the background and significance of the study about bendingcharacteristics of front rail in concept design stage, and summarizes the related research atpresent. Introduced the theory of thin-walled box section beam bending characteristicswhich is put forward by KECMAN, and research its calculation process in-depth. Thesimplified model of bending characteristics of front rail in concept design stage proposed bythis thesis is based on this theory. The simplified model is established by beam elements andnonlinear rotational spring unit in HyperMesh. The characteristics of nonlinear rotational spring unit obtained from the theoretical model in Chapter2. The analysis results comparewith detailed model of front rail for conceptual design prove that the simplified model putforward in this thesis can be used to analysis the bending characteristics of front rail inconcept design stage. In order to facilitate the application of simplified model proposed bythis thesis for engineers, the parametric modeling process is studied. Finally, the responsesurface method based on orthogonal experimental design is investigated in this thesis. Inorder to improve crashworthiness of front rail, cross-section parameters as design variables,orthogonal design for the arrangements of test point, good statistics and high precisionresponse surface model established, optimization analysis base on particle swarmoptimization algorithm, and get a good optimization results, proposed guidance to modifythe section parameters of front rail.