大变形扭转塑性硬化的实验和仿真研究

通过拉伸和扭转实验以及理论分析发现:在扭转实验中,当等效名义伸长率达到 286％时发生扭断,在此之前无明显局部化现象出现;相比较而言,单轴拉伸实验中的试件在颈缩失稳断裂时标距的最大伸长率仅为 29％.因此,用实心圆柱的扭转实验作为研究低碳钢这类弹塑性材料在大变形特征下的更为有效的基本实验,而以单轴拉伸实验作为补充是十分必要的.并通过数值模拟对在扭转过程中弹性核演变的历史进行了分析.

TEST AND SIMULATION FOR LARGE DEFORMED TORSION AND PLASTIC HARDENING

Through both tension and torsion tests and theoretical analyses, we found that, in torsion test, when the equivalent nominal elongation rate reached 286%, the specimen was failure without occurring localization phenomena. In contrast, the largest elongation rate was only 29% when plastic necking and unstable fracture occurred in uniaxial tension test. Thus, it is important to use torsion test as the effective basic test for studying the character of elastic-plastic materials at large deformation, while the uniaxial tensile test could be used as the supplement. According to the simulation, the evolution history of elastic core is also discussed during the torsion process.