Effect of Material Anisotropies of Hot-Rolled High-Strength Steel Sheet on Localized Deformation Behavior in Hole Expansion - Part-I Experimental Consideration to Circular and Oval Hole

Abstract

In this study, the effect of the material anisotropies of hot-rolled high-strength steel sheet on localized deformation behavior in hole expansion test has been investigated experimentally. First, the hole expansion test with the circular hole has been conducted to investigate the effect of anisotropies of material properties on the localized deformation behavior around the hole edge. Next, the hole expansion test with the oval hole has been conducted to investigate the effect of the major axis direction of the oval hole on the localized deformation behavior around the hole edge. As a result, it was clarified that the effect of anisotropies of r-value and n-value on the localized deformation behavior is strong, especially the anisotropy of n-value.

Effect of Material Anisotropies of Hot-Rolled High-Strength Steel Sheet on Localized Deformation Behavior in Hole Expansion - Part-II Simulation and Evaluation of Anisotropic Yield Function

“…, and the localization in T.D. is caused by the low r-value in R.D., as considered in Part-I [1]. Under the relatively small initial hole diameter as D 0 =20mm, the localization of thickness strain was higher in R.D.…”

“…The difficulty still remains, however, in the prediction of fracture initiation especially in stretch flanging, because of strong anisotropic behaviors of HSS sheet. In the first part (Part-I) of this study [1], the authors experimentally discussed the effect of the anisotropy on deformation behavior of HSS sheet in hole expansion test. In this Part-II, we numerically simulate the deformation of HSS sheet in circular hole expansion and evaluate the effect of anisotropic yield functions on the local reduction of thickness in HSS sheet.…”