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为研究固体推进剂在中应变率条件下的压缩力学性能,在高应变率液压伺服试验机上开展了单轴压缩实验,并获取了温度范围为-40~25℃及0.40~85.71s-1应变率下HTPB推进剂的应力-应变曲线。结果表明,本文的实验方法是有效的,温度和应变率对HTPB推进剂的压缩力学性能影响显著。随温度降低和应变率升高,应力-应变曲线特性变得更加复杂,并与准静态下的应力-应变曲线特性有明显区别。压缩模量E和压缩应力σ0.17随温度的降低和应变率的升高而逐渐增加,且均与应变率具有相对较好的线性双对数关系。在低温和较高应变率的双重作用下,-40℃,85.71s-1条件下的压缩模量E和压缩应力σ0.17分别为25℃,0.40s-1条件下数值的10.64倍和4.25倍。基于时温等效原理,得到了HTPB推进剂的压缩力学性能主曲线,该主曲线能够对低温较宽应变率范围内推进剂的压缩力学性能进行预测。在朱-王-唐非线性粘弹性本构模型的基础上,构建了考虑温度和应变率效应的固体推进剂中应变率压缩本构模型,并采用遗传算法拟合了本构参数。通过不同温度和应变率下预测结果与实验数据的比较,验证了模型的有效性。所建模型能够较好地描述0.17应变以内HTPB推进剂的压缩变形,可为低温中应变率下固体火箭发动机药柱的结构完整性分析提供理论基础。
In order to study the compressive mechanical properties of solid propellants at medium strain rate, a uniaxial compression test was carried out on a high strain rate hydraulic servo tester. The temperature range of -40 ~ 25 ℃ and strain of 0.40 ~ 85.71s-1 Stress-strain curves of HTPB propellants. The experimental results show that the experimental method is effective. The temperature and strain rate have significant influence on the compressive mechanical properties of HTPB propellants. As the temperature decreases and the strain rate increases, the characteristics of the stress-strain curve become more complex, which is obviously different from those of the quasi-static stress-strain curve. The compressive modulus E and compressive stress σ0.17 gradually increase with the decrease of temperature and strain rate, and have a relatively good linear logarithmic relationship with the strain rate. Under the double action of low temperature and high strain rate, the compressive modulus σ and compressive stress σ0.17 at 85 ℃ and 85.71s-1 at -40 ℃ are respectively 10.64 and 4.25 at 25 ℃ and 0.40s-1 Times Based on the time-temperature equivalence principle, the main curve of compressive mechanical properties of HTPB propellants was obtained, which can predict the compressive mechanical properties of propellants in a wide range of strain rates. Based on the Zhu-Wang-Tang nonlinear viscoelastic constitutive model, a constitutive model of strain rate compression in solid propellant considering the effect of temperature and strain rate was constructed, and the constitutive parameters were fitted by genetic algorithm. Through the comparison of the predicted results with the experimental data at different temperature and strain rates, the validity of the model is verified. The model can well describe the compression deformation of HTPB propellant within 0.17 strain, which can provide theoretical basis for structural integrity analysis of solid rocket motor grain at low temperature and medium strain rate.