Wang Xueren, Wang Yanchao, Qiang Hongfu, Bai Jianfang, Zhao Zhipeng, Luo Chao
Zhijian Laboratory, Rocket Force University of Engineering, Xi'an, 710038, China.
School of Astronautics, Northwestern Polytechnical University, Xi'an, 710072, China.
Sci Rep. 2025 Apr 25;15(1):14461. doi: 10.1038/s41598-025-99388-9.
For the propellant grain of solid rocket motors (SRMs) with circular inner surfaces, the generalized Maxwell model (GMM) and the generalized Kelvin-Voigt model (GKV) are used to characterize the relaxation properties of the grain's elastic modulus and the creep properties of Poisson's ratio, respectively. Based on the elastic-viscoelastic correspondence principle, an analytical expression for viscoelastic stress that simultaneously considers the time-dependent nature of elastic modulus and Poisson's ratio is derived. Based on this, a parametric analysis of the stress distribution in the grain under internal pressure is conducted. The results indicate that the hoop stress on the inner surface of the grain is most critical at the beginning of loading. As the thickness of the propellant grain increases, this initial tensile stress decreases moderately, but the duration of tensile stress increases. Increasing the thickness or stiffness of the combustion chamber casing moderately reduces the hoop stress during the initial loading and shortens the duration of tensile stress. Accurate measurement of the creep properties of Poisson's ratio has a significant impact on improving calculation accuracy. The stress calculation results under gradual pressurization are lower than those under instantaneous pressurization. The conclusions provide a reference for analyzing the structural integrity of propellant grains.
对于具有圆形内表面的固体火箭发动机（SRM）推进剂药柱，广义麦克斯韦模型（GMM）和广义开尔文 - 伏伊特模型（GKV）分别用于表征药柱弹性模量的松弛特性和泊松比的蠕变特性。基于弹性 - 粘弹性对应原理，推导了同时考虑弹性模量和泊松比随时间变化特性的粘弹性应力解析表达式。在此基础上，对药柱在内压作用下的应力分布进行了参数分析。结果表明，药柱内表面的环向应力在加载开始时最为关键。随着推进剂药柱厚度的增加，这种初始拉应力适度减小，但拉应力持续时间增加。适度增加燃烧室壳体的厚度或刚度可降低初始加载期间的环向应力，并缩短拉应力持续时间。准确测量泊松比的蠕变特性对提高计算精度有显著影响。逐步加压下的应力计算结果低于瞬时加压下的结果。这些结论为分析推进剂药柱的结构完整性提供了参考。
