Non-linear Deformation Behavior during Unloading in Various Metal Sheets
Non-linear Deformation Behavior during Unloading in Various Metal Sheets
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DOI：
10.2355/isijinternational.55.1067
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发表时间：
2015-05
影响因子：
1.8
通讯作者：
T. Hama;Ryogo Matsudai;Yota Kuchinomachi;H. Fujimoto;H. Takuda
中科院分区：
文献类型：
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作者：
T. Hama;Ryogo Matsudai;Yota Kuchinomachi;H. Fujimoto;H. Takuda
研究了低碳钢板（体心立方金属）、铝合金板（面心立方金属）和镁合金板（六方密排金属）在单轴拉伸下卸载时的变形行为。还使用晶体塑性有限元方法来研究材料之间变形行为的差异。卸载过程中的非线性在镁合金板中最大，并且低碳钢板比铝合金板表现出更大的非线性。另一方面，由卸载曲线的线性近似确定的表观弹性模量并不总是与非线性中观察到的特征一致，并且随着非线性程度的增加，这种不一致变得明显。研究发现，非线性程度与应变率敏感性有很强的相关性，这表明表观弹性模量不适合模拟高应变率敏感性材料的卸载行为。晶体塑性分析表明，如实验结果所示，镁合金板的非线性比其他两种板大得多。模拟结果表明，卸载过程中产生非线性的原因之一是滑移系统之间临界解析剪应力的差异。
The deformation behavior during unloading was examined under uniaxial tension in a mild steel sheet (body-centered cubic metal), an aluminum alloy sheet (face-centered cubic metal), and a magnesium alloy sheet (hexagonal close packed metal). A crystal plasticity finite-element method was also used to investigate the difference in the deformation behavior among on the materials. The nonlinearity during unloading was the largest in the magnesium alloy sheet, and the mild steel sheet showed a larger nonlinearity than the aluminum alloy sheet. On the other hand, the apparent elastic moduli determined from the linear approximation of unloading curves were not always consistent with the characteristics observed in the nonlinearity, and this inconsistency became pronounced as the degree of nonlinearity increased. It was found that the degree of nonlinearity would have a strong correlation with the strain rate sensitivity, suggesting that the apparent elastic modulus was not suitable to model the unloading behavior for materials with high strain rate sensitivity. The crystal plasticity analysis demonstrated that the nonlinearity was much larger in the magnesium alloy sheet than in the other two sheets as observed in the experimental results. The simulation results suggested that one of the reasons that gave rise to the nonlinearity during unloading would be the difference in the critical resolved shear stresses among the slip systems.