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    基于机器学习的GH4169合金Johnson-Cook本构参数反演方法

    Inversion Method Based on Machine Learning for Johnson-Cook Constitutive Parameters of GH4169 Alloy

    • 摘要: 采用拉丁超立方采样方法对基于文献的GH4169合金Johnson-Cook(J-C)本构参数空间进行均匀采样,利用有限元模拟输出对应参数组合的应力-应变曲线。以模拟应力-应变曲线数据为输入,J-C本构参数为输出,采用前向神经网络(FNN)模型、随机森林(RF)模型、循环神经网络(RNN)模型进行训练,并对模型进行贝叶斯超参数优化,通过测试集的决定系数R2对3种模型的参数反演能力进行对比;以试验获得的应力-应变曲线数据为输入,利用训练后的机器学习模型输出对应的J-C本构参数,再通过有限元模拟生成应力-应变曲线,并与试验结果进行对比。结果表明:FNN模型、RF模型和RNN模型测试集的R2分别为0.847,0.499,0.741,FNN模型的表现最佳,而RF模型的表现最差,不适用于GH4169合金J-C本构参数的反演;采用FNN模型反演J-C本构参数预测得到850~1 050 ℃下GH4169合金的压缩应力-应变曲线与试验曲线更加吻合,平均相对误差比采用RNN模型反演J-C本构参数和由试验曲线拟合本构参数预测得到的曲线分别低约11.9%和2.1%,验证了机器学习方法在反演GH4169合金J-C本构参数上的有效性。

       

      Abstract: The Latin hypercube sampling method was used to uniformly sample the Johnson-Cook (J-C) constitutive parameter space for GH4169 alloy from literatures. The stress-strain curve corresponding to the parameter combination was output by finite element simulation. With the simulated stress-strain curve data as input and J-C constitutive parameters as output, the forward neural network (FNN) model, random forest (RF) model and recurrent neural network (RNN) model were used for training, and Bayesian hyperparameter optimization was conducted on the models. The parameter inversion ability of the three models was compared by the determination coefficient R2 of the test set. With the stress-strain curve data obtained by testing as input, the corresponding J-C constitutive parameters were output by the trained machine learning model, and then the stress-strain curve was generated by finite element simulation and compared with the test results. The results show that the R2 of FNN model, RF model and RNN model on the test set was 0.847, 0.499, 0.741, respectively; FNN model had the best performance, while RF model had the worst performance and was not suitable for the inversion of material constitutive parameters. The compressive stress-strain curves of GH4169 alloy at 850–1 050 ℃ predicted with FNN model inversion J-C constitutive parameters were more consistent with the test curves, and the average relative error was about 11.9% and 2.1% lower than that of the predicted curves obtained with RNN model inversion J-C constitutive parameters and test curve fitting constitutive parameters, respectively, which verified the effectiveness of the machine learning method in the inversion of J-C constitutive parameters of GH4169 alloy.

       

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