冲击载荷下中碳低合金钢的动态力学性能与J-C本构模型的改进

Dynamic mechanical properties of medium carbon low alloy steel and improvement of J-C constitutive model under impact load

对淬火和高温回火的中碳低合金钢进行准静态室温拉伸实验以及不同应变速率下的室温冲击压缩实验,发现中碳低合金钢具有明显的应变速率敏感效应与增塑效应。为了建立能真实反映中碳低合金钢在较强冲击载荷下塑性变形特征的本构模型,通过引进绝热温升热软化项,以及修正应变速率敏感系数来改进传统的Johnson-Cook (J-C)本构模型,并采用多变量线性拟合与遗传算法(GA)求解模型参数。结果显示:在不同应变速率下,改进的J-C本构模型结果与实验结果吻合效果较好。表明改进的J-C本构模型可以很好地描述中碳低合金钢在动态冲击载荷下的力学行为,为工程中采用数值模拟方法研究中碳低合金钢的动态力学行为提供理论参考。

The quasi-static tensile tests and impact compression tests under different strain rates at room temperature were carried out on quenched and high-temperature tempered medium carbon low-alloy steel, and it is found that the material has obvious strain rate sensitive effect and plasticizing effect. In order to establish a constitutive model, which could truly reflect the plastic deformation characteristics of medium carbon low alloy steel under strong impact load, the traditional Johnson-Cook(J-C) constitutive model was revised by adding the thermal softening term of adiabatic temperature rise(ATR)and modifying the strain rate sensitive coefficient, and the model parameters were solved by multi-variable linear fitting and genetic algorithm(GA). The research shows that the results of the improved J-C constitutive model are in good agreement with the experimental results under different strain rates, and the improved J-C constitutive model well describes the mechanical behavior of medium carbon low alloy steel under dynamic impact load, which provides theoretical reference for the use of numerical simulation method in engineering to study the dynamic mechanical behavior of medium carbon low alloy steel.