Experimental studies and numerical modeling of the specimen and grain size effects on the flow stress of sheet metal in microforming
Experimental studies and numerical modeling of the specimen and grain size effects on the flow stress of sheet metal in microforming
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DOI：
10.1016/j.msea.2011.06.076
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发表时间：
2011-09-25
期刊：
影响因子：
6.4
通讯作者：
Fu, M. W.
中科院分区：
文献类型：
--
作者：
Chan, W. L.;Fu, M. W.
本文通过纯铜的拉伸试验和数值模拟，研究了晶粒尺寸和试样尺寸对微成形板材流动应力的交互作用。基于不同的假设，提出了模型来分析规模效应现象。结果表明，随着试样与晶粒尺寸比的减小，流变应力呈线性减小。随着晶粒尺寸的减小，晶界厚度减小，晶界体积分数增大。晶界厚度的变化与晶粒尺寸的变化不成正比。此外，晶界的分数增加的应变和试样的晶粒尺寸比。基于有限元模拟，发现模拟的流动应力，这是基于所识别的晶界厚度使用所提出的模型建模，具有良好的一致性与实验结果。此外，还基于表面层模型分析了流变应力的尺寸效应。根据实验结果，提出了识别表面和内部晶粒特性的方法。所确定的属性是适用于模拟试样和晶粒尺寸对流动应力的相互作用。本研究为深入了解微成形过程中的塑性变形行为提供了理论依据。(C)2011 Elsevier B.V.保留所有权利。
In this research, the interactive effect of grain and specimen sizes on the flow stress of sheet metal in microforming is investigated via the tensile test of pure copper and numerical modeling. Models based on different assumptions are proposed to analyze the size effect phenomenon. It is found that the flow stress decreases linearly with the decrease of the ratio of specimen to grain sizes. The grain boundary thickness decreases and its volume fraction increases with the decrease of grain size. The variation of grain boundary thickness is not proportional to the variation of grain size. Furthermore, the fraction of grain boundary increases with the strain and the ratio of specimen to grain sizes. Based on the FE simulation, it is found that the simulated flow stress, which is modeled based on the identified grain boundary thicknesses using the proposed models, has a good agreement with the experimental result. In addition, the size effect on flow stress is also analyzed based on the surface layer model. The methodology to identify the surface and internal grain properties is proposed based on the experimental result. The identified properties are applicable in modeling of the interactive effect of specimen and grain sizes on flow stress. This research thus provides an in-depth understanding of the plastic deformation behavior in microforming process. (C) 2011 Elsevier B.V. All rights reserved.