基于GA优化的7055铝合金Johnson–Cook流变本构建模及其FEA应用

目的 研究7055铝合金高温流变行为，建立高精度流变本构模型和有限元分析(Finite Element Analysis，FEA)仿真模型。方法 基于Gholamzadeh温度修正模型和Evans摩擦修正模型，计算修正7055铝合金热压缩流动应力，以排除试验过程中变形温升和摩擦对流动应力的影响;针对修正后的流动应力构建Johnson–Cook本构模型，依托MATLAB编程采用遍历法优化模型参考条件，并引入遗传算法(Genetic Algorithm，GA)对模型参数进行优化，通过流动应力子程序二次开发实现优化后的模型在商用软件DEFORM中的应用，以预测变形工件的应力应变分布与成形载荷。结果 经温度和摩擦修正的流动应力与试验值相近;采用遍历法优选参考条件后的Johnson–Cook本构模型流动应力预测值与试验值之间的平均相对误差绝对值(Average Absolute Relative Error，AARE)为4.57%，经GA优化后降至3.50%，实现了精度的提升。基于该模型二次开发的DEFORM模拟平台能准确预测成形载荷，预测值与试验值之间的AARE为2.42%。结论 构建了具有较高精度的流动应力本构模型，并基于其开发了有限元仿真模型，仿真结果与试验结果吻合良好，该仿真模型能够为7055铝合金热加工工艺的精确设计和优化提供有效指导。

GA Optimized Johnson-Cook Constitutive Model for 7055 Aluminum Alloy and Its Application in FEA

The work aims to investigate the flow behavior of 7055 aluminum alloy at high temperature, and construct constitutive model and finite element analysis (FEA) simulation model with high precision. Based on the Gholamzadeh temperature correction model and Evans friction correction model, the hot compression flow stress of 7055 aluminum alloy was calculated and corrected to eliminate the effect of deformation temperature rise and friction on the flow stress during the test. Johnson-Cook constitutive model was constructed for the modified flow stress, and the reference conditions of the model were optimized by traversal method based on MATLAB programming, and Genetic Algorithm (GA) was introduced to optimize the model parameters. In order to predict the stress-strain distribution and forming load of the deformed workpiece, the optimized model was applied to commercial software DEFORM through the secondary development of flow stress subroutine. The corrected flow stress was close to the test value. After reference condition optimization, the average absolute relative error (AARE) between the predictions of Johnson-Cook model and the corrected values was 4.57%, which reduced to 3.50% after GA optimization and the accuracy was improved. Furthermore, the AARE value between predicted forming load by FEA and test value was 2.42%, indicating precise prediction capability of the secondary developed DEFORM simulation platform. The optimized constitutive model and the corresponding FEA platform have high prediction precision, and the simulation results agree well with the test results, which offers significant guide for the accurate design of thermomechanical processing and optimization of 7055 aluminum alloy.