MECHANISMS OF LOCALIZED NECKING DEFORMATION OF SHEET METALS
来源期刊：中国有色金属学报(英文版)1997年第2期
论文作者：Zhou Weixian
文章页码：72 - 76
Key words：sheet metals; localized necking ;mechanisms
Abstract: Abandoning the various assumptions and prerequisites in the existing theories, the whole process of tensile instable deformation of sheet metals from its occurrence, development to Lüders type localized necking deformation was analyzed using the classical plastic mechanics on the basis of the principle of minimum strain energy. The results showed that when the load bearing ability in the direction of maximum principal stress of an element of sheet metal reached the extreme, i.e. the condition of d P 1=0, the instable deformation occurs. In the tension compression strain fields, as the instable deformation progresses, the ratio of the two principal stresses, χ (= σ 2/ σ 1), increases gradually and P 1 reduces gradually, i.e. the direction of the instant extreme of load bearing ability turns successively. Until it is perpendicular to the direction in which the normal strain increment is zero, then the localized necking deformation takes place. In the biaxial tension strain fields, as the instable deformation progresses, P 1 remains constant while χ decreases gradually until causing the condition of plane strain increment to emerge, then the localized necking deformation takes place.
