作者：姚迪, 蔡力勋, 包陈

作者单位：西南交通大学力学与工程学院, 四川 成都 610031

关键词：TF法; 单轴拉伸; 颈缩; 大变形; 有限元模拟; 材料本构关系

摘要：

材料拉伸直至破坏的单轴本构关系对于材料与结构的大变形分析和裂纹问题中的变形行为研究有重要意义。该文提出一种将实验与数值分析相结合获取材料拉伸直至颈缩破断全程本构关系的新方法TF法(tensile test-finite element method)。通过构造初始微小缺陷实现拉伸试样的颈缩有限元模拟;应用自制对中夹具,结合DIC(digital image correlation)方法和应变传感器来测量材料拉伸全程的标距位移、试样颈缩根部直径和颈缩区轮廓线;应用逐步逼近原理并借助开发的ANSYS APDL命令流程序实现材料全程单轴真实本构关系求解的迭代计算。应用TF方法得到的全程材料本构关系对SS316L和T225NG合金拉伸试样的颈缩行为进行有限元模拟分析,结果表明:颈缩区两端的载荷-位移曲线、最小截面直径-位移曲线和颈缩区轮廓线的数值分析结果与实验结果吻合良好;对SS316L小曲率半径漏斗试样的载荷-位移曲线的模拟结果也与实验结果吻合良好。还给出SS316L和T225NG合金两种材料的Ramberg-Osgood全程单轴本构模型参数与等效破断应力应变,讨论两种材料单轴拉伸试样破断时颈缩根部横截面的应力分布。

Approach for full-range uniaxial constitutive relationships of ductile materials

YAO Di, CAI Li-xun, BAO Chen

School of Mechanics and Engineering, Southwest Jiaotong university, Chengdu 610031, China

Abstract: The description of constitutive relationships of materials up to failure is very significant for the analyses of large deformation and fracture problems of engineering structures. This paper presents a new method to determine the full-range uniaxial constitutive relationship of a material. This approach combining tensile tests that lead to specimen necking and the finite element method is named as TF method. The method firstly implements the necking simulation of a tensile specimen by constructing an initial defect. And then the deformation of the specimen in gauge length range, the cross section diameter at necking root and necking contours of the specimen can be measured by using the self-made centering clamps, DIC (digital image correlation) technique and strain sensor. Finally, ANSYS APDL command stream program is developed to conduct the iterative solution of the constitutive relationship based on load versus displacement curve. The research results show that the necking simulation results of the specimens for 316L stainless steel and T225NG titanium alloy are much closed to the testing results. The simulation for a funnel specimen of SS316L with small curvature radius is investigated. Besides, the parameters of Ramberg-Osgood constitutive model and the failure stress distributions on the cross section at necking root of the specimens for the two materials are given.

Keywords: TF method; uniaxial tension; necking deformation; large deformation; finite element simulation; constitutive relationship of materials

2014, 40(5): 5-13  收稿日期: 2014-4-9;收到修改稿日期: 2014-6-3

基金项目: 国家自然科学基金项目(11072205)

作者简介: 姚迪(1990-),男,山东荷泽市人,博士,研究方向为材料本构关系与断裂力学。

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