Aging kinetics modeling and storage life prediction of composite solid propellants under thermomechanical coupling

Abstract

In order to investigate the influence of tensile stress on the aging behavior of HTPB propellants and to predict their storage life at 298.15 K, three high-temperature accelerated aging experiments and six thermomechanical coupling accelerated aging experiments were designed and conducted. An aging kinetics model based on the Arrhenius equation was developed, in which both aging temperature and aging stress were incorporated as coupled factors affecting the degradation rate. The results show that under thermomechanical coupling conditions, the propellant’s creep deformation exhibits a strong dependence on the aging stress, and considerable irreversible deformation remains after unloading. Aging stress not only accelerates oxidation crosslinking reactions but also induces molecular chain alignment along the stress direction, thereby markedly enhancing the axial mechanical response of the material. Scanning electron microscopy (SEM) observations indicate that the temperature-stress coupling effect further weakens the chemical bonding at the filler-matrix interface. Model predictions indicate that propellant’s storage life decreases from 17.19 years under a single temperature field to 7.83 years under thermomechanical coupling conditions. This reduction highlights the significant role of aging stress in accelerating performance degradation. These findings provide crucial theoretical insights for accurately assessing the long-term storage performance of solid rocket propellants.