宽温域宽应变率下丁羟四组元HTPB推进剂单轴压缩力学行为

Uniaxial Compressive Mechanical Behavior of Four⁃component HTPB Propellant under Wide Temperature and Strain Rate Range

为研究丁羟四组元端羟基聚丁二烯(HTPB)推进剂在宽温域宽应变率下的单轴压缩力学行为,基于万能材料试验机、高速液压伺服试验机、分离式霍普金森压杆,结合可程式恒温恒湿试验机等温控手段,开展了宽温域宽应变率下的推进剂单轴压缩力学性能实验,获取了-40,-25,-10,20,50℃5个温度下10-4~103 s-1应变率的丁羟四组元HTPB推进剂的应力应变曲线,并建立了HTPB推进剂的分段式单轴压缩率温本构关系。结果表明,HTPB推进剂的力学响应存在显著的率温相关性,在任意应变率下其力学响应都呈阶段性变化,即线弹性阶段⁃非线性屈服阶段⁃应变软化阶段或应变硬化阶段;且在高应变率下,非线性屈服行为后的应变软化现象明显弱于低、中应变率。此外,高应变率时,随着温度的降低,应力应变曲线的变化速率逐渐减缓;而低、中应变率却恰恰相反,随着温度的降低,应力应变曲线的变化速率逐渐加快。HTPB推进剂的力学强度随着温度的降低显著增大,温度从50℃降低至-40℃时,HTPB推进剂试件在宽应变率作用下的最大应力从2.2~8.8 MPa增长至约11~22 MPa。同时基于实验数据构建了分段式率温本构关系,发现其在温度较高时拟合效果更好,能够较好地预测HTPB推进剂的力学行为。

In order to investigate the uniaxial compression mechanical behavior of four⁃component HTPB propellant under wide temperature and wide strain rate ranges,uniaxial compressive mechanical performance tests of propellant were conducted under wide temperature and strain rate ranges based on universal material testing machine,high⁃speed hydraulic servo testing ma⁃chine,split Hopkinson pressure bar,and programmatic constant temperature and humidity testing machine.Stress⁃strain curves of HTPB propellant under 10-4-103 s-1 at-40,-25,-10,20℃and 50℃were obtained,and the segmented uniaxial compres⁃sion rate⁃temperature constitutive relationship of HTPB propellant was established.The results indicate that the mechanical re⁃sponse of HTPB propellant exhibits a significant rate⁃temperature correlation.At any strain rate,its mechanical response under⁃goes staged changes,i.e.,linear elastic stage⁃nonlinear yield stage⁃strain softening or strain hardening stage.Moreover,at high strain rates,the strain softening phenomenon after the nonlinear yield behavior is significantly weaker than that at low and medi⁃um strain rates.In addition,at high strain rates,as the temperature decreases,the changing rate of the stress⁃strain curve gradual⁃ly slows down;while at low and medium strain rates,the changing rate of the stress⁃strain curve gradually increases as the tem⁃perature decreases.The mechanical strength of HTPB propellant increases significantly with decreasing temperature.When the temperature drops from 50℃to-40℃,the maximum stress under wide strain rate increases from about 2.2-8.8 MPa to 11-22 MPa.The segmented rate⁃temperature constitutive relationship constructed based on the experimental data has a better fit⁃ting effect at higher temperatures,which can better predict the mechanical behavior of HTPB propellant.