Storen-Rice法の局所くびれ解析における境界条件の乱れ

抄録

Reasonability of Storen-Rice method is discussed which is widely used for estimating the formability in stretch forming of sheet metals. One of the famous methods for analyzing localized necking had been proposed by Hill. But, the application of his analysis must be confined to the bi-axial forming where there is at least the direction t with no stretching, i.e., ε^^·u =0 in the forming sheet. Hence, this condition has been a serious obstacle for its application to the bi-axial stretch forming without fulfilling such condition. Storen and Rice proposed Δε^^·_tt=0 in place of ε^^·_tt=0, where Δ denotes difference between the regions separated by a necking plane. Moreover, in their analysis they imposed the equilibrium of traction rates acting between these regions. However, they ignored the necessity that these regions must be under a common boundary condition. We examine in this paper whether this necessity is satisfied or not in their method. Consequently, it is proved that it is not satisfied in general. Hence, their method cannot be reasonable for estimating the stretch formability of sheet metals.