Mechanical properties of double-base propellant at high strain rates and its damage-modified ZWT constitutive model
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摘要: 为了解双基推进剂在冲击载荷下的力学特性及本构行为,利用材料试验机和分离式霍普金森压杆(SHPB)对双基推进剂进行了单轴压缩实验,并对实验数据的有效性进行了检验。用二波法对实验数据进行处理,得到了双基推进剂的应力应变曲线。实验结果表明:双基推进剂具有明显的应变率相关性,动态下屈服应力与静态下相比明显提高,且屈服应力表现为应变率对数的双线性关系;双基推进剂屈服应变表现为延脆转换特性,在低应变率下表现为延展性,高应变率下表现为冲击脆化特性。利用含损伤朱王唐(ZWT)本构模型对实验结果进行了拟合,得到了模型中的本构参数,并对损伤因子项进行了分析。通过模型预测曲线与实验曲线的对比,发现含损伤ZWT本构能较好地描述双基推进剂在0~0.14应变范围内的力学特性。Abstract: To obtain the mechanical properties and constitutive behaviors of double-base propellant under impact loading, uniaxial compression experiments were performed on the material test machine and the split Hopkinson pressure bar (SHPB) device. The availability of the experimental data was examined, and the stress-strain curves were obtained by using the two-wave method. The experimental results indicate that the double-base propellant is a significant strain-rate-dependent material, the yield strength increases obviously at high strain rates compared with that under quasi-static loading, and the relationship between yield strength and logarithm of strain rate is bilinear. The yield strain of the doublebase propellant behaves in the effect of ductile-brittle transition, and it behaves in ductility at low strain rates as well as impact brittleness at high strain rates. The damage-modified ZWT constitutive model was used to fit the experimental data, and the parameters in the constitutive equation were obtained. Moreover, the damage factor was analyzed. Comparisons of the model-predicted curves with the experimental ones show that the damagemodified ZWT model can well predict the mechanical properties of the double-base propellant in the strain range from 0 to 0.14.
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