Effect of Cooling Load on the Safety Factor of Propellant Grains

Abstract

The reliability of propellant grains of a solid-propellant rocket is crucial to the performance of a missile. The environment temperature changes greatly from the curing to the firing conditions of the missile. The propellant grains inside the missile experiences similar temperature variations as well. In this study, the time–temperature shift principle, cumulative damage theory, and finite element software are used to evaluate the time–temperature-dependent behavior of the structural integrity of the solid-propellant grains under cooling loads. The results show that the cooling load from the curing temperature to the storage temperature significantly influences the safety factor of the propellant grains; the larger the cooling rate, the smaller the safety factor. Thus, safety factors of the propellant grains can be tuned to a desired value within certain limits by adjusting the cooling load with a smaller cooling rate.