考虑微观结构特征长度演化的内变量黏塑性本构模型
发布时间：2018-10-29 09:48
【摘要】：在金属晶体材料高应变率大应变变形过程中,存在强烈的位错胞尺寸等微观结构特征长度细化现象,势必对材料加工硬化、宏观塑性流动应力产生重要影响。基于宏观塑性流动应力与位错胞尺寸成反比关系,提出了一种新型的BCJ本构模型。利用位错胞尺寸参数,修正了BCJ模型的流动法则、内变量演化方程,引入了考虑应变率和温度相关性的位错胞尺寸演化方程,建立了综合考虑微观结构特征长度演化、位错累积与湮灭的内变量黏塑性本构模型。应用本文模型,对OFHC铜应变率在10-4~103 s-1、温度在298~542K、应变在0~1的实验应力-应变数据进行了预测。结果表明:在较宽应变率、温度和应变范围内,本文模型的预测数据与实验吻合很好;与BCJ模型相比,对不同加载条件下实验数据的预测精度均有较大程度的提高,最大平均相对误差从9.939%减小为5.525%。
[Abstract]:In the process of high strain rate and large strain deformation of metallic crystal materials, there is a strong phenomenon of microstructural length refinement, such as dislocation cell size, which is bound to have an important effect on material work hardening and macroscopic plastic flow stress. Based on the inverse relationship between the stress of macroscopic plastic flow and the size of dislocation cell, a new BCJ constitutive model is proposed. Based on the parameters of dislocation cell size, the flow rule of BCJ model and the evolution equation of internal variables are modified. The evolution equation of dislocation cell size considering the correlation of strain rate and temperature is introduced, and the evolution of characteristic length of microstructures is established. Visco-plastic constitutive model of internal variables for dislocation accumulation and annihilation. Using this model, the experimental stress-strain data of OFHC copper at 10-4 103s-1, temperature 298N 542K and strain 0U 1 have been predicted. The results show that the predicted data of this model are in good agreement with the experiment in a wide range of strain rate, temperature and strain. Compared with the BCJ model, the prediction accuracy of the experimental data under different loading conditions is greatly improved, and the maximum average relative error is reduced from 9.939% to 5.525%.
【作者单位】： 昆明理工大学机电工程学院;
【基金】：国家自然科学基金项目(11462008)
【分类号】：O344.4
，
本文编号：2297353
[Abstract]:In the process of high strain rate and large strain deformation of metallic crystal materials, there is a strong phenomenon of microstructural length refinement, such as dislocation cell size, which is bound to have an important effect on material work hardening and macroscopic plastic flow stress. Based on the inverse relationship between the stress of macroscopic plastic flow and the size of dislocation cell, a new BCJ constitutive model is proposed. Based on the parameters of dislocation cell size, the flow rule of BCJ model and the evolution equation of internal variables are modified. The evolution equation of dislocation cell size considering the correlation of strain rate and temperature is introduced, and the evolution of characteristic length of microstructures is established. Visco-plastic constitutive model of internal variables for dislocation accumulation and annihilation. Using this model, the experimental stress-strain data of OFHC copper at 10-4 103s-1, temperature 298N 542K and strain 0U 1 have been predicted. The results show that the predicted data of this model are in good agreement with the experiment in a wide range of strain rate, temperature and strain. Compared with the BCJ model, the prediction accuracy of the experimental data under different loading conditions is greatly improved, and the maximum average relative error is reduced from 9.939% to 5.525%.
【作者单位】： 昆明理工大学机电工程学院;
【基金】：国家自然科学基金项目(11462008)
【分类号】：O344.4
，
本文编号：2297353
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