铝合金7050-T7451高温高应变率本构方程及修正

Research and Revise on Constitutive Equation of 7050-T7451 Aluminum Alloy in High Strain Rate and High Temperature Condition

通过分离式霍普金森压杆(SHPB)及准静态压缩实验研究铝合金7050-T7451高温高应变率下流变应力特征,利用准静态实验数据获得本构方程应变强化参数,利用SHPB实验数据获得室温下不同应变率(400～2500s-1)的应变率强化参数,以及应变率为2500s-1不同温度下(250～600℃)的热软化参数。利用不同幂次多项式对Johnson-Cook本构方程的热软化项拟合,最终选择五次多项式作为修正后本构方程热软化项。利用修正后本构方程对不同温度条件下应力-应变曲线进行预测,实验数据与预测曲线表现出良好一致性。

The flow stress behavior of 7050-T7451 aluminum alloy at high temperature and high strain rate was investigated by split Hopkinson pressure bar （SHPB） and quasi-static test system. The strain hardening parameters were obtained by the quasi-static test experiment data. The strain rate hardening parameter at various strain rates （400-2500s-1） and room temperature,and the thermal sof- tening parameter at various temperatures where strain rate is 2500s-1 ,were obtained by the split Hop- kinson pressure bar experiment data. A new thermal softening equation is proposed to revise the John- son-Cook constitutive equation ,where the a quintie polynomial equation is ehoosed as the new thermal softening equation. According to the comparison between predict curves and experiment curves of stress-strain at various temperatures, the modified constitutive equation can fit the experiment date well.