A new method based on the EMF ring expansion test has been suggested for determining the dynamic characteristics of annealed and as-received aluminum 1050 H18 sheet. The proposed method does not need any expensive hardware or data collector. After performing quasi-static (QS) tensile tests, two coils and three sets of rings were prepared. The rings were expanded by coils at different voltages, and the strains induced were measured using 2D scanners. An inverse modeling algorithm was used as a tool to determine the strain rate hardening coefficient by minimizing the difference between experimentally measured strain and that calculated from FEM simulation. The obtained strain-rate hardening coefficient of the material shows that annealed aluminum 1050 sheet is sensitive to strain rate, whereas the as-received is not. The obtained results showed that the as-received aluminum 1050 sheet depicts brittle failure behavior in both QS tensile test and high strain rate ring expansion test, but the annealed one withstands strains above 0.25 at both mentioned strain rates. The proposed method is successful in determining the flow curve of the material in sheet forming at high strain rates.

Graphic Abstract

中文翻译：

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用电磁成型环膨胀试验测定铝1050板的动态特性

提出了一种基于 EMF 环膨胀试验的新方法，用于确定退火和原样的 1050 H18 铝板的动态特性。所提出的方法不需要任何昂贵的硬件或数据收集器。在进行准静态 (QS) 拉伸试验后，准备了两个线圈和三组环。这些环通过不同电压的线圈展开，并使用 2D 扫描仪测量引起的应变。逆向建模算法被用作通过最小化实验测量的应变与 FEM 模拟计算的应变之间的差异来确定应变率硬化系数的工具。获得的材料应变率硬化系数表明，退火的 1050 铝板对应变率敏感，而原样则不然。获得的结果表明，原样的 1050 铝板在 QS 拉伸试验和高应变率环膨胀试验中均表现出脆性破坏行为，但退火板在上述两种应变率下均能承受 0.25 以上的应变。所提出的方法成功地确定了材料在高应变率下板材成形的流动曲线。

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