Ha Jinjin, Fones Johnathon, Kinsey Brad L, Korkolis Yannis P
Department of Mechanical Engineering, University of New Hampshire, 33 Academic Way, Durham, NH 03824, USA.
Department of Integrated Systems Engineering, The Ohio State University 1971 Neil Avenue, Columbus, OH 43210, USA.
Materials (Basel). 2020 Sep 25;13(19):4285. doi: 10.3390/ma13194285.
The plasticity and formability of a commercially-pure aluminum sheet (AA1100-O) is assessed by experiments and analyses. Plastic anisotropy of this material is characterized by uniaxial and plane-strain tension along with disk compression experiments, and is found to be non-negligible (e.g., the r-values vary between 0.445 and 1.18). On the other hand, the strain-rate sensitivity of the material is negligible at quasistatic rates. These results are used to calibrate constitutive models, i.e., the Yld2000-2d anisotropic yield criterion as the plastic potential and the Voce isotropic hardening law. Marciniak-type experiments on a fully-instrumented hydraulic press are performed to determine the Forming Limit Curve of this material. Stereo-type Digital Image Correlation is used, which confirms the proportional strain paths induced during stretching. From these experiments, limit strains, i.e., the onset of necking, are determined by the method proposed by ISO, as well as two methods based on the second derivative. To identify the exact instant of necking, a criterion based on a statistical analysis of the noise that the strain signals have during uniform deformation versus the systematic deviations that necking induces is proposed. Finite element simulation for the Marciniak-type experiment is conducted and the results show good agreement with the experiment.
通过实验和分析评估了工业纯铝板（AA1100-O）的塑性和可成形性。通过单轴和平面应变拉伸以及圆盘压缩实验对该材料的塑性各向异性进行了表征，发现其不可忽略（例如，r值在0.445至1.18之间变化）。另一方面，在准静态速率下，该材料的应变速率敏感性可忽略不计。这些结果用于校准本构模型，即以Yld2000-2d各向异性屈服准则作为塑性势和Voce各向同性硬化定律。在一台完全仪器化的液压机上进行了Marciniak型实验，以确定该材料的成形极限曲线。使用了立体型数字图像相关技术，这证实了拉伸过程中诱导的比例应变路径。从这些实验中，极限应变，即颈缩的开始，通过ISO提出的方法以及基于二阶导数的两种方法来确定。为了确定颈缩的确切时刻，提出了一种基于对均匀变形期间应变信号的噪声与颈缩引起的系统偏差进行统计分析的准则。对Marciniak型实验进行了有限元模拟，结果与实验显示出良好的一致性。
