TY - JOUR A1 - Yanagimoto, Jun A1 - Oya, Tetsuo A1 - Kawanishi, Seiichiro A1 - Tiesler, Nicolas A1 - Koseki, Toshihiko T1 - Enhancement of bending formability of brittle sheet metal in multilayer metallic sheets JF - CIRP Annals N2 - The formability of multilayer metallic sheets is evaluated by tensile, V-bending, hat bending and hemming tests. A monolithic type-420J2 stainless steel sheet cannot be formed because of poor elongation as small as 1.7%. Marked enhancement of the bending formability was observed in the bending of type-420J2 stainless steel sheets when they are layered by type-304 stainless steel sheets and composed into a multilayer metallic sheet. The mechanism of the enhancement of the formability of type-420J2 stainless steel in a multilayer metallic sheet is investigated analytically by focusing on the delay of the initiation of necking, and by performing stress analysis by finite element method (FEM). Y1 - 2010 U6 - https://doi.org/10.1016/j.cirp.2010.03.109 VL - 59 IS - 1 SP - 287 EP - 290 ER - TY - JOUR A1 - Oya, Tetsuo A1 - Tiesler, Nicolas A1 - Kawanishi, Seiichiro A1 - Yanagimoto, Jun A1 - Koseki, Toshihiko T1 - Experimental and numerical analysis of multilayered steel sheets upon bending JF - Journal of Materials Processing Technology N2 - In this study, the bending formability of multilayered steel sheets is evaluated by tensile tests, V-bending tests, and hemming tests. Enhanced formability was observed in these experiments, namely, the constituent high-strength materials were elongated beyond the original fracture strain limit. As a result of this effect, multilayered steel sheets were successfully formed in V-bending tests and even in hemming tests. Observations using a scanning electron microscope verified that no delamination occurred at interfaces. To represent the geometrical features of a multilayered steel sheet, a solid-element model under an isostrain condition was utilized in finite element modeling, where the rule of mixtures was adopted to obtain the flow curve of the constituent high-strength material, and a good agreement with experimental results was observed. Analyses using this finite element model were conducted to investigate the effect of the geometry on the springback of multilayered steel sheets undergoing V-bending. Y1 - 2010 U6 - https://doi.org/10.1016/j.jmatprotec.2010.07.003 VL - 210 IS - 14 SP - 1926 EP - 1933 ER -