TC4钛合金高精度热塑性唯象本构模型研究

Research on High-Precision Thermoplastic Phenomenological Constitutive Models of TC4 Titanium Alloy

摘要:

为了准确预测TC4钛合金的热塑性成形效果，研究了TC4钛合金的高温流变行为，并构建了高精度的热塑性唯象本构模型。首先，在温度范围973~1123 K和应变率范围0.01~1 s^-1的条件下进行了TC4钛合金高温拉伸试验。基于试验数据，建立了六阶多项式应变补偿的Arrhenius本构模型和修正的Johnson-Cook本构模型，并利用麻雀搜寻算法（sparrow search algorithm，SSA）对2种本构模型的参数进行了优化。最后，通过统计分析，评估了上述4种TC4钛合金热塑性唯象本构模型的预测能力。研究结果表明，Arrhenius本构模型在有限的试验数据情况下能够实现较高的预测精度，但其参数优化的空间有限。与之相比，修正的Johnson-Cook本构模型虽然初始预测精度较低，但具有更大的参数优化空间。基于SSA优化的Johnson-Cook修正本构模型的预测结果与试验结果吻合良好，能够作为TC4钛合金的高精度热成形数值仿真的基础。

Abstract:

To accurately predict the thermoforming process of TC4 titanium alloy, the high-temperature rheological behavior of TC4 titanium alloy was investigated, and a high-precision thermoforming phenomenological constitutive model was developed. Firstly, high-temperature tensile tests of TC4 titanium alloy were conducted at 973-1123 K with strain rates of 0.01-1 s^-1. Based on the experimental data, two constitutive models were established: an Arrhenius constitutive model with strain compensation and a modified Johnson-Cook constitutive model. Sparrow search algorithm (SSA) was employed to optimize the model parameters. Finally, the predictive abilities of the phenomenological constitutive models for TC4 titanium alloy were assessed using statistical analysis. The results indicate that the Arrhenius constitutive model achieves relatively high predictive accuracy despite limited experimental data. However, it has a restricted parameter optimization space. In contrast, the modified Johnson-Cook constitutive with lower predictive accuracy, offers a larger parameter optimization space. The SSA-optimized modified Johnson-Cook constitutive model provides a good fit with experimental results, serving as a solid foundation for high-precision numerical simulations of TC4 titanium alloy thermoforming.