各向同性均质弹塑性材料圆棒试样单向拉伸试验变形特性与应力应变本构关系的相关性分析

针对各向同性均质弹塑性材料圆棒试样单向拉伸试验,分别从理论上以及采用有限元法分析了变形特性与应力应变本构关系的相关性,探讨了形成颈缩的必要条件及实际颈缩形貌的形成过程。结果表明,等效塑性应变ε_p达到一定临界值后,流变应力σ₀不再随等效塑性应变ε_p的增大而增大的材料的应力应变本构特性,以及试样为非理想圆柱体是产生颈缩的必要条件,颈缩后期内部形成断裂是导致颈缩区最小截面位置弧形轮廓线曲率半径较小的原因。 

Correlation Analysis of Deformation Characteristics and Stress-strain Constitutive Relationship of Round-bar Specimens with Isotropic Homogenous Elasto-plastic Materials by Unidirectional Tensile Test

Based on the uniaxial tensile test of round-bar specimens of isotropic homogeneous elasto-plastic material, the correlation between the deformation characteristics and the stress-strain constitutive relationship are analyzed theoretically. By the finite element method, the necessary conditions for the formation of necking and the formation process of the actual necking morphology are discussed. The results show that the material stress-strain constitutive properties and the specimen are non-ideal, and that a cylinder is a necessary condition for necking. When the equivalent plastic strain (ε_p) reaches a certain critical value, the flow stress (σ₀) no longer increases with the increase of ε_p. The internal fractures formed in the later stage of necking are the reasons for the smaller curvature radius of the arc contour at the minimum cross-sectional position of the necking area.