The used comuputer code Calembour enabled to modelize the nonlinear steel behaviour. The performance of the computer code were studied on an industrial automotive part from Audi and on a laboratory part from PSA (half oilpan). This preliminary study pointed out convergency problems due to the distorsion and/or the mesh elements turnaround which occur in high compression areas. It led the team to introduce a new degree of freedom in order to take into account the sheet gripping. The contact algorithm was also modified in order to take into account the vertical wall and to introduce a artificial clearance between the tools. A complex laboratory tool was created with preliminary consultations of Renault, PSA and Sollac, built by Sollac and then assembled on an instrumented press of their laboratory in order to realize the laboratory tests, which were planned to occur in two stages. These tests were made in order to validate the computer code as far as rheological and process parameters were concerned. The first part of the validation of Calembour using a complex laboratory tool was carried out by Sollac on two sheet metals, so-called Solpress FeP 06 and Solphor P 220. The aim was to study the effect of material properties on the deformed geometry of the stamped parts and the drawing forces. The differences between both mild steels are significant, even if the blank geometry is simple and the punch displacement is small. Renault carried out the numerical simulations of the Sollac part using the software Calembour on a workstation without noticing any numerical problem. The predictions of the thickness distribution, the drawing loads and the draw-in were correct but not in good agreement with the test results. It results that the computer code is not very sensitive to the material properties. The effect of the mesh refinement has been analysed but it does not show any significant improvement on the accuracy of the predictions. The analysis using the refined mesh is not justified. The tests adjusment as for this second stage was particulary difficult to do because of the introduction of the drawing ring. The authors could not reach the maximum punch stroke because it was impossible to supress wrinkling without breaking the sheet steel.
Modelidation de l'emboutissage de pieces automobiles complexes
Rechnersimulation des Tiefziehens kompliziert geformter Karosseriebauteile aus Tiefziehblech
Computer simulation of the deep drawing of complicated formed car parts
1999
159 Seiten, 89 Bilder
Report
French
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