Equivalence of Storen-Rice's method with Hill's for the analysis of localized necking
Moritoki Hitoshi; Okuyama Eiki
Abstract:Application range of Storen-Rice method is discussed which is 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 in the bi-axial forming where there is at least the direction with no stretching, ie, edottt =0 in the forming sheet. Hence this condition becomes an obstacle for its application in biaxial stretch forming. Storen-Rice proposed Dedottt =0, in place of edottt =0, where D denotes difference between the regions separated by necking plane. This proposal is suggesting that the condition edottt =0 might be removed, but it has not been proved whether the removal of the condition is realized or not. Then, on the equilibrium condition proposed in their analysis, the range of applicable forming is examined where the existence of multiple solution can be made sure. Consequently, it is found that it is possible to have multiple solution in the only forming condition satisfying edottt =0. Therefore, the forming limit obtained in biaxial stretching are in the outside of the application range, and they are an imaginary solution. Key Words:plasticity, plastic instability, localized necking, formability, multiple solution