Study On Wrinkling In Auto Panels Based On Universal Formability Theory

With the growth of Chinese automobile industry, reducing vehicle development cycle, improving quality and comfort are the decisive factors for increasing competitiveness in automobile market. Auto panel is an important constituent part of automotive. As most auto panels are composed of the free-form surfaces with complex sptical structure and large forming dimensions, the non-uniform pressures on blank during stamping process can generate some surface defects, like wrinkling, cracking and so on. This thesis manily concerns on the wrinkling defect of auto panel in finite element environment based on Universal Formability Theory. The study includes the following main areas.(1) To increasing the commonality of KMAS-SFT software, this thesis writes some codes to read the postpositional processing files of DYNAFORM software, and build pst file which could be read by KMAS-SFT.(2) This thesis increases the wrinkle height calculation function of wrinkling analysis module in KMAS-SFT software.(3) To analysis and eliminate wrinkles in sheet metal surface, this thesis establishes a wrinkling analysis process to determine the formability state of sheet metal, analyse the stamping deformation and eliminate wrinkles. For manual analysis in DYNAFORM postprocessing module and automatic analysis in wrinkling analysis module of KMAS-SFT software, this thesis provides difference analysis processes.(4) Taking an auto front fender as example, the thesis presents the wrinkling analysis process in DYNAFORM postprocessing module. This analytical result indicates the validity of the process to analysis and eliminate wrinkle defect.