平面应变颈缩扩展与剪切断裂的数值模拟

采用虚功率增率有限元法及Ｊ２形变理论，模拟韧性金属平面应变颈缩扩展，剪切断裂演化过程。运用载荷控制的自动识别方法以及各增量步间Ｅｕｌｅｒ控制方法，实现了均匀变形与非均匀变形临界状态的稳定过渡，采用本构方程的Ｅｕｌｅｒ显式积分，对Ｊ２形变理论塑性加载与弹性卸载的不连续性进行了改进，保证了变形局部化模拟过程的可靠性，最后，讨论了不同硬化指数及初始几何不均匀性对局部化力学行为的影响。

NUMERICAL SIMULATION FOR THE NECKING DEVELOPMENT AND THE SHEAR BAND FKACTURE UNDER PLANE STRAIN TENSION OF DUCTILE METALS

In this paper,the evolution of the necking development and the shear band fracture under planestrain tension of ductile metals was numerically simulated by the FEM based on the virtual power-rate functionaland the J2 deforrnation theorv of plasticity,Asmooth transition of the crisis from uniform deformation to neckingdevelopment was realized with the numerical identification method of the unloading point controlled by Load.Inaddition,the disconnection between the plastic-loading and the shortcoming of the J2D theory,was improved bythe Euler explicit integration of constitutive equation,Lastly,the influence of the hardening exponent of materials(n)and the initial geornetric irnperfection(f0)on the localization behavior was discussed.