Abstract A unified viscoplastic constitutive model is proposed coupling fluid pressure rate control and damage evolution for warm medium forming (WMF), which also includes flow stress function, hardening law and dislocation density evolution. The pressure rate and damage behavior are investigated based on the experimental data of Ref. (Lang et al., 2013) [10] and the fracture morphology observations of specimens. The constitutive equations are discretized and derived through the fourth-order Runge-Kutta method. Meanwhile, the material constants of this model are determined using the Genetic Algorithm. The proposed constitutive model is applied to the WMF process of AA7075-O sheet and compared with the results of Ref. [10] . The error between calculated and experimental data is quantified using the average absolute relative error (AARE). Results indicate that the prediction accuracy of the proposed constitutive model is significantly improved compared with Ref. [10] , also, the predictions compare well with the experimental results. The new constitutive model can effectively predict the flow behavior of AA7075-O in WMF.

中文翻译：

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用于模拟暖介质形成过程中流体载荷和损伤演化的粘塑性本构方程

摘要 提出了一种统一的粘塑性本构模型，结合流体压力速率控制和温介质形成（WMF）损伤演化，该模型还包括流动应力函数、硬化规律和位错密度演化。基于参考文献的实验数据研究了压力速率和损坏行为。(Lang et al., 2013) [10] 和试样的断裂形态观察。本构方程通过四阶Runge-Kutta方法进行离散和推导。同时，该模型的材料常数是使用遗传算法确定的。所提出的本构模型应用于 AA7075-O 板材的 WMF 工艺，并与参考文献的结果进行比较。[10]。使用平均绝对相对误差 (AARE) 量化计算数据和实验数据之间的误差。结果表明，与参考文献相比，所提出的本构模型的预测精度显着提高。[10] ，同样，预测与实验结果相比较。新的本构模型可以有效预测 AA7075-O 在 WMF 中的流动行为。