Evaluation on prediction abilities of constitutive models considering FEA application

Constitutive model plays an important role in the numerical simulations of metal forming. However, th~ influence of the models on the calculation is vague. Based on the stress-strain data of A1 7050 and Ti-6A1-4V alloy generated by isothermal compressive tests, the Johnson-Cook （JC） and Arrhenius-type （A-type） hyperbolic sine model were fitted to obtain the constants. Flow stresses directly calculated by the equations were compared with th~ experiment results, and rigid-plastic finite element analyses （FEA） utilizing these models were employed to simulate th~ same compression processes. The results show that A-type model has higher accuracy in the direct prediction of roy stress, even outside of the fit domain. The simulation results using A-type model also have higher agreement with th~ experiment; however, the suitability is affected by the referential parameters employed in the regression process, h terms of the overall deformation and strain distributions, there are slight differences among the simulation results usint these two models.

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。