长期贮存发动机中HTPB推进剂老化特性及蠕变本构模型

Aging characteristics and creep constitutive model of HTPB propellant for long-term storage motors

为了研究固体火箭发动机长期贮存期间老化对推进剂力学性能的影响,开展了三种温度(50℃,60℃与70℃)下为期60天的高温加速老化试验。对老化前后HTPB推进剂进行了定速拉伸试验与蠕变试验,并采用扫描电镜观察了其表面细观形貌。引入扩裂元件,结合Arrhenius方程,建立了含老化因子的推进剂蠕变全过程本构模型,利用试验数据拟合了模型参数并验证了其有效性。结果表明:随着老化进程的加剧,推进剂最大伸长率逐渐减小,最大抗拉强度会依次出现下降、波动、上升三个阶段。所建本构模型能较好地表征贮存1.5年后推进剂的蠕变全过程,预测曲线与试验结果曲线最大误差为13.35%。

In order to study the effects of aging on the mechanical properties of propellant during long-term storage of solid rocket motors,a 60-day thermal accelerated aging test was carried out at three temperatures(50℃,60℃and 70℃).The constant speed tensile test and creep test of HTPB propellant before and after aging were carried out,and the surface morphology was observed by scanning electron microscope.The constitutive model of the whole creep process with aging factor was established by introducing the cracking element and combining the Arrhenius equation.The model parameters were fitted and validated based on the experimental data.The results show that with the increase of aging process,the maximum elongation of propellant decreases gradually,and the maximum tensile strength will appear in three stages in sequence:decreasing,fluctuating,and increasing.The constitutive model can well characterize the whole creep process of propellant after 1.5 years of storage,and the maximum deviation between the prediction curve and the test result curve is 13.35%.