Abstract In this study, a novel analytical method for predicting bending and springback behaviours of hexagonal close-packed (HCP) sheet metals is presented. The proposed analytical approach is developed by using the Cazacu-Barlat 2004 asymmetric yield function and isotropic plastic hardening rule. This model can be used to determine bending moment-curvature relationships and springback of HCP metals under uniaxial and plane strain loading conditions. Furthermore, to capture the nonlinearity in unloading and to improve springback prediction, the variable elastic modulus approach is implemented in the proposed model. The proposed new model reveals that reverse effects of the back force on springback behaviours cannot be found under the plane strain condition, which could not be found by using any existing models. Moreover, the analytical model is implemented into Abaqus via UMAT subroutine for its application in complex cases, and a numerical model is then developed as a showcase. The proposed methods are validated by using those experimental results available in literature. The results show considerable improvements by considering the plane strain condition and nonlinear unloading.

中文翻译：

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六方密排金属板回弹行为研究

摘要 在这项研究中，提出了一种预测六角密堆积 (HCP) 金属板弯曲和回弹行为的新分析方法。建议的分析方法是通过使用 Cazacu-Barlat 2004 不对称屈服函数和各向同性塑性硬化规则开发的。该模型可用于确定单轴和平面应变加载条件下 HCP 金属的弯矩-曲率关系和回弹。此外，为了捕捉卸载中的非线性并改进回弹预测，在所提出的模型中实施了可变弹性模量方法。所提出的新模型表明，在平面应变条件下无法发现反力对回弹行为的反向影响，而使用任何现有模型都无法发现这一点。而且，分析模型通过 UMAT 子程序实现到 Abaqus 中，用于复杂情况下的应用，然后开发一个数值模型作为展示。通过使用文献中可用的那些实验结果来验证所提出的方法。通过考虑平面应变条件和非线性卸载，结果显示出相当大的改进。