DP780高强钢板材高应变率变形行为及本构模型

Deformation behavior and constitutive model of DP780 high strength steel at high strain rates

基于MTS准静态拉伸和分离式霍普金森杆冲击拉伸实验对DP780高强钢板材在0.001、1150、1900、2800和4200 s^（-1）应变率水平下的本构行为进行了描述,获得了其高应变率变形规律,并建立了修正的Johnson-Cook（JC）动态本构模型。结果表明,动态冲击拉伸时,DP780板材的变形行为与准静态时显著不同,呈现显著的应变率强化特征。动态拉伸条件下的屈服强度和抗拉强度都要明显高于准静态条件下,屈服和抗拉强度在动态条件下随应变率升高也会有所增加,但由于绝热升温效应,应变率达到2800 s^（-1）左右时不再出现增加的趋势。基于动态拉伸数据建立的修正的JC本构模型能很好地描述和预测实验结果。

The MTS quasi-static and split Hopkinson bar dynamic tensile tests at strain rates 0. 001,1150,1900,2800 and 4200 s^（-1） were carried out to study the constitutive behavior of DP780 high strength steel,the law of high strain rate deformation was obtained,and the Johnson-Cook（ JC） dynamic constitutive model was proposed and modified subsequently. The results show that the deformation behavior of DP780 sheets under dynamic tension is of great difference from that of the quasi-static tensile process,exhibiting a significant strain rate strengthening effect. The yield and ultimate tensile strength of DP780 under dynamic tension condition are obviously higher than that under quasi-static condition,and the strengths increase with the increasing strain rates. However,the tendency of increasing disappears when the strain rate increases to 2800 s^（-1） because of the adiabatic heating effect. The modified JC model established based on dynamic tension data can describe and predict the tensile curves well.