COMPLAS 2023

Improved Accuracy of Edge Crack Analysis of High Strength Steel Sheets

  • Okubo, Shuji (Gunma University)
  • Otake, Yusei (Gunma University)
  • Nishida, Shinichi (Gunma University)
  • Nedachi, Tomoki (Toa Industries Co.,Ltd.)

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This paper reports on the edge crack analysis of high strength steel sheets using the finite element method analysis. In press forming of high-strength steel sheets, cracking of the plate edge is a major issue, and prediction by FEM analysis is required. In FEM, molding analysis is performed with the stress and strain values of the plate edge being 0. However, in the actual product, the sheared part is cut when the material is cut due to tensile or compressive stress or strain, which reaches the limit value of the material. Forming limit diagram (FLD) is generally used for crack prediction in press forming FEM analysis of steel sheets. In the current FEM, since the sheared state of the plate edge is not taken into consideration, molding starts from the origin of FLD, and it is not possible to predict the occurrence of edge cracking. The purpose of this study was to improve the analysis accuracy by incorporating the strain value of the plate edge of the actual material after shearing into the finite element method analysis. Based on the amount of notch deformation at break measured by the notch tensile test, the notch tensile test analysis was performed and the limit damage value was calculated. After that, the strain amount and depth of the material generated on the plate edge during shearing were obtained by shear test analysis.