An Analytical Study of Macro/Microscopic Effects on the Forming Limit of Polycrystalline Materials

宏观/微观对多晶材料形成极限影响的分析研究

基本信息

批准号：
05650082
负责人：
IMATANI Shoji
金额：
$ 1.47万
依托单位：
Kyoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05650082/
关键词：
Polycrystal Forming limit Finite element method Anisotropy Crystal plasticity Surface roughness 成形性

项目摘要

Finite element analyzes have been carried out in order to evaluate both macro-and micro-scopic effects on the forming limit of polycrystalline materials. Theobtained results are as follows :1. The material anisotropy which is inevitably induced through the production process of rolling has a predominant influence on the onset as well as the growth of strain localization. In particular the direction of necking is generated perpendicular to the rolling direction when subjected to a tensile loading, while it extends to the parallel direction under a balanced biaxial stretching. The analytical results show qualitative agreement with experiments for both cases of loading pattern.2. In order to simulate real polycrystalline metals, a sophisticated mesh generation scheme is proposed in such a way that each Voronoi polygon is assigned to a crystal with random slip plane while the boundary corresponds to a grain boundary. The analytical result shows that the deformation in the polycrystal is inhomogeneous due to the difference in slip system and that the stiffness of grain boundary plays an important role in the evolution of the inhomogeneity. An experimental study is also carried out on a specially prepared specimen with micro-grid indentation. It is observed that the surface roughness has a periodicity with two of three crystal grain size and that it is caused by the discrepancy at the grain boundary. Further simulation with more elements in fully three-dimensional state will enable us to evaluate the forming limit of metals in terms of the microscopic inhomogeneity.

为了评估对多晶材料的形成极限的宏观和微观影响，进行了有限元分析。被视为的结果如下：1。不可避免地通过滚动生产过程引起的材料各向异性对菌株定位的发作和生长产生了主要影响。特别是，在承受拉伸载荷时，颈部的方向垂直于滚动方向，而在平衡的双轴拉伸下，它延伸至平行方向。分析结果显示了与两种负载模式的实验的定性一致性。2。为了模拟真实的多晶金属，提出了一个复杂的网格生成方案，以使每个Voronoi Polygon被分配给具有随机滑动平面的晶体，而边界对应于晶界。分析结果表明，由于滑移系统的差异，多晶的变形是不均匀的，并且晶界的刚度在不均匀性的演变中起重要作用。还对具有微电网压痕的特殊准备的标本进行了实验研究。据观察，表面粗糙度具有三个晶体晶粒尺寸中的两个周期性，并且是由晶界的差异引起的。在完全三维状态下使用更多元素的进一步仿真将使我们能够根据微观不均匀性评估金属的形成极限。