| The stiffness of the car body plays a very important role in evaluating the car’skey performance indicators, such as reliability, security, NVH. So the analysis of thestiffness characteristics is indispensable at the car body design phase.Based on the investigation of the related domestic and overseas research in thisfield, the finite element model of a car BIW is established，static stiffness werecarried on, at the same time, the static stiffness testing had been finished．Resultscomparison between the testing and analysis revealed the structural capabilities andverified the finite model’s correctness, for mutual combination with each other．Ouranalytic works in concrete are mainly as follows：(1)Through simplifying the geometric model and using HyperMesh and Radioss，a fine FEM model of the body shell and frame is establishe d，and then, analysis of theresult is made．This paper describes how to deal with the detail structure，partswelding and the simulation of the joints between the body and the frame．The paperalso discusses how to simulate the load and boundary conditions un der torsional andbending loads to meet the actual loading manner of the test．Through the analysis，thispaper concludes the result of stiffness in torsional and bending load conditions，thedeformation and stiffness of body and frame.(2)In this paper, static stiffness test system was established and the fixture usedfixed the BIW with the frame was designed following the practical stucture. Thenbending stiffness and torsional stiffness of the car BIW were tested with this testsystem. This paper concludes the result of stiffness in torsional and bending loadconditions，the deformation and stiffness of body and frame. Furthermore，the paperfinds out the vulnerable areas and deformation of main openings in torsional andbending load conditions．Through the stiffness measuring test, the paper found asimple and convenient way of measuring the of body and frame，and a discussion onseveral possible problem and critical technical issues of test process, and validatedthe correctness of the FEM model．(3)Finally, the results of the test and the simulation were compared, It was foundthat the simulation calculated and test values of the static stiffness of the car are ingood agreement with each other, which was in a limit of allowable error. The paperdiscussed the possibility of mutual support and crosscheck between the simulation and the testing, in addition to, the paper also took a research and evaluation on thecause of the errors which was existed in the testing.The conclusions of this paper can provide tech nological basis and method forproduct development, model Change and optimizing of car body structure of the samekind. |
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