Evaluation on prediction abilities of constitutive models considering FEA application
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Constitutive model plays an important role in the numerical simulations of metal forming. However, the influence of the models on the calculation is vague. Based on the stress-strain data of Al 7050 and Ti-6Al-4V alloys generated by isothermal compressive tests, the Johnson-Cook (JC) and Arrhenius-type (A-type) hyperbolic sine models were fitted to obtain the constants. Flow stresses directly calculated by the equations were compared with the experiment results, and rigid-plastic finite element analyses (FEA) utilizing these models were employed to simulate the same compression processes. The results show that A-type model has higher accuracy in the direct prediction of flow stress, even outside of the fit domain. The simulation results using A-type model also have higher agreement with the experiment; however, the suitability is affected by the referential parameters employed in the regression process. In terms of the overall deformation and strain distributions, there are slight differences among the simulation results using these two models.
Key wordsconstitutive model metal forming numerical simulation performance isothermal compression
本构模型在金属塑性成形数值模拟中扮演着重要角色,然而其对计算的影响仍不明确。本文基 于Al 7050 和Ti-6Al-4V 合金的等温压缩实验应力-应变曲线,对Johnson-Cook (JC)以及Arrhenius-type (A-type) 双曲正弦模型进行了拟合并得到表达式;将应用2 个方程直接预测的流动应力与实验结果进 行比较,同时利用刚塑性有限元数值方法对热压缩过程进行模拟,发现对于实验数据的直接预测, A-type 模型的预测精度高于JC 模型的,对拟合数据以外的实验数据也一样。从数值模拟结果来看, 利用A-type 模型的计算结果与实验更加吻合,但吻合程度受拟合所采用参考参数的影响;从模拟得到 的整体变形和应变分布来看,利用2 种模型的结果差别不大。
关键词本构模型 金属成形 数值模拟 性能 等温压缩
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