Identification of plastic behaviors of structural steels at very large deformation

超大变形时结构钢塑性行为的识别

基本信息

批准号：
10650461
负责人：
OBATA Makoto
金额：
$ 1.6万
依托单位：
NAGOYA INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650461/
关键词：
plasticity constitutive relation plastic rupture inverse analysis large deformation analysis material tests

项目摘要

The initiation of brittle cracks in members degrades the ductility of steel structures. As observed in the Hyogoken Nanbu Earthquake, such brittle fracture is often triggered by preceding ductile fracture. The estimation of ultimate behaviors and deformation capacity of steel structures, therefore, critically depends on the ductile fracture of its members. However, few numerical method to investigate the ductile fracture of members is available because of the lack of the understandings of the quantitative aspects of such material characteristics. we have proposed an alternative experimental method to circumvent the difficulty using an FEM-based inverse analysis. This method provides a consistent way to determine the material constants by a simple uniaxial test. In the present work, we show that the FEM analysis with Gurson's model could be a suitable tool for the estimation of ductility limit of steel members. Once the material parameters are properly determined, the initiation of plastic rupture can be predicted with reasonable accuracy in terms of void volume fraction. However, we also note that the experimental result suggests the needs for the further investigation in some cases. In view of practical importance, we proposed a simple extension of Gurson's model to so called a kinematic hardening model. The modified model is coded as a plug-in user subroutine of an FEM program DIANA for practical numerical analysis.

成员中脆性裂纹的启动降低了钢结构的延展性。正如在nanbu地震中观察到的那样，这种脆性断裂通常是由延性裂缝引起的。因此，钢结构的最终行为和变形能力的估计在很大程度上取决于其成员的延性断裂。但是，由于缺乏对此类材料特征的定量方面的理解，很少有数值方法可以研究成员的延性裂缝。我们提出了一种替代实验方法，以使用基于FEM的反向分析来规避难度。该方法提供了一种一致的方法来通过简单的单轴测试来确定材料常数。在目前的工作中，我们表明使用Gurson模型的FEM分析可能是估计钢构件延展性极限的合适工具。一旦正确确定了材料参数，就可以在空隙体积分数方面准确地预测塑料破裂的启动。但是，我们还指出，实验结果表明在某些情况下需要进一步研究。鉴于实际的重要性，我们提出了Gurson模型的简单扩展，以称为运动硬化模型。修改后的模型被编码为FEM程序Diana的插件用户子例程，用于实用数值分析。