| Currently,finite element simulation technology has been widely used in body structure design and stamping forming of covering parts.In the analysis of traditional car structure performance,designers often direct the design of 3D digital models directly into the finite element simulation software.The strength,stiffness,vibration,impact and fatigue analysis of the body parts are simulated by "white grid",and ignore that the mechanical properties of changes has the influence on the structure performance after stamping forming.After stamping by mold,body covering parts will produce sheet thickness change,strain and stress inevitably,these factors will affect the strength and stiffness of body structure,the traditional finite element analysis of car body mainly been done in the design stage of body structure and seldom consider the stamping changes in mechanical properties.So this article is based on concurrent engineering theory,using the front door of a car as the research object,analyzing the door cover parts stamping mechanical property's change on the door of the influence of the structure performance in order to get fine simulation analysis method to the actual body structure performance,by adopting the combination.of simulation and test methods.The main contents and conclusions of this paper are as follows:The finite element pretreatment software was used to simplify the model structure,geometry cleanup,meshing and quality control,etc.,established a complete finite element model of the door and the first four-order natural frequency and vibration mode for the door were obtained through the Hypemesh software.One step inverse forming technology was used in stamping forming simulation for the door panels by KMAS software,the result of simulation analysis of thickness,stress and strain was been as the initial value of the thickness,stress and strain for the structure performance analysis.Bring the results about simulation analysis of the doors and the doors into simulation analysis of the car door structure performance,carrying out the numerical analysis of the displacement and stiffness of the car door respectively.Compared with the finite element data which obtained by the white mesh division method,the maximum displacement,maximum stress and torsional rigidity have significant changes after taking the forming factor into consideration.According to the structural characteristics of the car door,the numerical analysis of car door mode and the experimental study of car door mode have been completed respectively,and the analysis process of the numerical calculation mode and experimental mode of the car door have been designed.According to the analysis steps of experimental mode,excitation system,the number and position of excitation point and the support mode of structure are selected in turn.Collecting experimental data and analyzing by modal analysis system,the frequency and mode of each order mode are obtained under the condition of car door test.Compared with the frequency and mode which acquired by the finite element calculation modal analysis after taking the stamping forming history into account,the comparison of the two analysis results show that the analysis results of the numerical calculation modal of mechanical properties which have taken stamping forming history into consideration are close to that of the experimental modal and the error is less than 5%.Based on the above analysis results,it is necessary to take the influence of mechanical properties of sheet metal forming into account to improve the simulation accuracy of car body structure performance. |
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