降伏曲面上に形成される尖り点を考慮した弾粘塑性モデルによるモードIき裂進展解析

Abstract

It has been confirmed by experiments and crystal plasticity analysis that a vertex is formed at the loading point of the yield surface in the stress space during plastic deformation. However, most past deformation analyses for crack tip behavior have used plasticity models with a classical normality flow rule. In this study, we introduce a non-normality flow rule, which considers the formation of a vertex on the yield surface. We investigate the effect of vertex formation on Mode I crack growth behavior for cyclic loading. Numerical results show that both crack tip opening displacement and crack growth are greater for the model with the non-normality flow rule than for the standard normality flow rule. The distribution of equivalent plastic strain near the crack tip indicates that the model with the non-normality rule leads to localized plastic deformation, which is not seen in the case where the standard normality flow rule is adopted.