The improvement of stress correction in post-necking tension of cylindrical specimen
The improvement of stress correction in post-necking tension of cylindrical specimen
复制标题
圆柱形试件缩颈后拉伸应力修正的改进
DOI：
10.1177/0309324719852875
复制
发表时间：
2019-04-01
影响因子：
1.6
通讯作者：
Meng, Xiangrui
中科院分区：
文献类型：
--
作者：
Chen, Junfu;Guan, Zhiping;Meng, Xiangrui
在圆柱形试件的颈缩后拉伸中，基于现有分析模型的应力修正在大应变时有较大的误差。在本研究中，通过对不同硬化指数(0.05~0.3)的圆柱形试件进行一系列有限元模拟，评估了Bridgman模型、Siebel模型和Chen模型对这些模型的预测能力。对颈缩截面上的应力和应变分布的数值分析表明，在这些分析模型中，对应于大应变的修正应力的相当大的误差可能主要归因于在颈缩截面上的均匀应变分布的假设。为了提高这些模型的颈后应力预测精度，综合考虑了颈项的几何形状和材料特性，提出了相应的修正策略。在此基础上，根据数值模拟结果，给出了考虑颈项横截面半径和硬化指数的修正公式。最后，利用这些公式对Q345圆柱体试件颈缩后拉伸应力进行了修正，并与用反演法确定的应力进行了比较。结果表明，改进后的模型显著提高了大应变下后缩颈应力的预测精度。
In post-necking tension of cylindrical specimen, the stress corrections based on the current analytical models have relatively significant errors at large strains. In this study, the prediction capability of these models involving Bridgman model, Siebel model and Chen model is evaluated by performing a series of finite element simulations of uniaxial tension of cylindrical specimen with different hardening exponents varied from 0.05 to 0.3. Numerical analysis of stress and strain distributions on the necking cross section indicates that the considerable errors of the corrected stresses corresponding to large strains might be mainly attributed to the assumption of uniform strain distribution on the necking cross section in these analytical models. The modification strategies of these models are presented in order to improve their prediction accuracy of post-necking stresses, taking geometrical configuration of neck and material properties into consideration. Accordingly, the modification formulas are proposed based on simulation results, involving the radius of cross section of neck and the hardening exponent. Finally, these formulas are used to correct the stresses in the post-necking tension of Q345 cylindrical specimen, which are compared with the stresses identified through inverse method. The results indicate that the modified models significantly improve the prediction accuracy of post-necking stresses at large strains.