中文摘要：

为获取金属材料颈缩后的真实本构关系,提出了一种新型的试验-数值耦合方法,即NE（Numerical and experimental）法。该方法的基本原理是将单轴拉伸试验的荷载-位移曲线作为目标,通过有限元迭代运算,不断修正输入的应力-应变曲线,直至荷载-位移曲线的模拟结果与试验结果完全吻合或达到误差要求时,即得到真实应力-应变曲线。基于该原理,开发了一套数值模拟程序CONST以实现测试技术的自动化并节省操作时间。为验证NE法的有效性,将传统理论计算方法与NE法获得的材料真实本构关系进行对比,并对圆棒和矩形试件分别进行拉伸模拟,结果表明NE法对两种试件均适用,且NE法获得的荷载-位移曲线、颈缩变形特征等较理论计算方法更为精确。所提方法解决了金属材料单轴拉伸颈缩至断裂期间获取真实应力-应变曲线存在的困难,对材料性能评价及结构变形分析具有重要的理论及工程应用价值。

英文摘要：

In order to obtain the material true constitutive relation of ductile metal in the post-plastic localization regime （necking stage）, we proposed an experimental-numerical combined method （NE method）, based on the simple tension test results. An iterative scheme was used to minimize the errors between the simulated and experimental loaddisplacement curves by modifying the imported stress-strain data step by step, and the true stress was determined when the error was less than a given value. In addition, we developed a numerical simulation program CONST to implement this algorithm automatically and save operating time. As a verification, the true stress-strain curves obtained by the traditional theoretical approach and NE method were compared, and employed to analyze the large deformation behavior of both cylindrical and rectangular specimens. The results showed that NE method was applicable for both of the specimens and could achieve an adequate description of the mechanical response of the materials after necking formation more effectively. The proposed method overcomes the difficulties in the acquisition of true constitutive relation from necking to fracture during uniaxial tensile, and has an important theoretical and engineering value in the evaluation of the material properties and structural deformation analysis.