Research On Stamping Forming Characteristics And Defects Judging Of Laminated Steel Sheet

Laminates steel sheet is increasingly used for the special structure to improve vehicle's vibration-damping performance without adding additional weight and meet the strength and rigid requirement at the same time. Therefore, the formability of laminated steel sheet has become the key problems of present research. This paper has invetigated the stamping forming characteristics and defects for laminated steel sheet funded by National Natural Science Foundation of China(NO.50775142).Study the influence of punch speed on the springback behavior of laminated steel sheet through 90°V-shape bending experiment and discover that springback angle of laminated steel sheet has time-lag effect. When the punch speed varies in the range of 0.5-5mm/s, springback value of laminated steel sheet decreases to a steady value with the punch speed increasing.The springback behavior of laminated steel sheet(0.83mm), solid sheet (0.83mm), skin sheet(0.4mm) was also considered through the 90°V-shape model, and the results showed that among laminated steel sheet, solid sheet and skin sheet, skin sheet had the maximum springback angle, solid sheet came second, and laminated steel sheet had the minimum springback angle but closed to the value of solid sheet, which meant the laminated steel sheet had similar springback behavior with solid sheet.Delamination criterion was established according to the obtained data in shear strength experiment and normal adhesive strength expe from riment in reference[15] based on the displacement method. In these two experiments the relative limit displacement between the top and bottom sheet of laminated steel sheet was got, so the limit displacement could be used as the delamination criterion. Skin sheets FLD was set as FLD criterion because the skin sheets were parts of the whole laminated steel sheet.Developed the laminated steel sheet forming defects judgment system using MFC with the tool of OpenGL to clearly visualize the defects, such as delamination, fracture and wrinkle. When comparing the judgment results of delamination and fracture defects with experiment results, it showed that the laminated steel sheet forming defects judgment system could reasonably predict these defects.?...