Influence of curvature variation on edge stretchability in hole expansion and stretch flanging of advanced high-strength steel

摘要: Advanced high-strength steels (AHSSs) have been widely used in automotive structural components to reduce the vehicle weight and improve safety, while edge stretchability is an important characteristic besides traditional material property parameters. In presented work, a new method proposed investigate influence of curvature variation on stretching performance by introducing evaluation index, i.e., strain localization intensity index (SLII), which strain-based defined as ratio theoretical failure (first appearing at location with maximum curvature) same time minimum curvature. The algorithm calculate SLII based elliptical hole expansion simulation was developed details. Numerical experimental studies typical AHSS-DP780 semi-ellipse stretch flanging were conducted geometric features performance. Results showed that got more severe increasing eccentricity. More caused declined stretchability. Fractures prone position largest Comparative during than under Perimeter elongation (PE) limit height (FLH) for calculated compared, showing terms PE FLH sensitive eccentricity expansion.