@article{YanagimotoOyaKawanishietal., author = {Yanagimoto, Jun and Oya, Tetsuo and Kawanishi, Seiichiro and Tiesler, Nicolas and Koseki, Toshihiko}, title = {Enhancement of bending formability of brittle sheet metal in multilayer metallic sheets}, series = {CIRP Annals}, volume = {59}, journal = {CIRP Annals}, number = {1}, doi = {10.1016/j.cirp.2010.03.109}, pages = {287 -- 290}, abstract = {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).}, language = {en} } @article{OyaTieslerKawanishietal., author = {Oya, Tetsuo and Tiesler, Nicolas and Kawanishi, Seiichiro and Yanagimoto, Jun and Koseki, Toshihiko}, title = {Experimental and numerical analysis of multilayered steel sheets upon bending}, series = {Journal of Materials Processing Technology}, volume = {210}, journal = {Journal of Materials Processing Technology}, number = {14}, doi = {10.1016/j.jmatprotec.2010.07.003}, pages = {1926 -- 1933}, abstract = {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.}, language = {en} }