Abstract: Long-term storage-induced aging of the bonded interface in solid rocket motors (SRMs) is a critical factor influencing structural integrity and service reliability. Conventional high-temperature accelerated aging tests cannot realistically reproduce the stress-time coupled fields experienced under actual service conditions, leading to limitations in predicting interfacial property degradation. In this study, multi-level constant-stress aging tests were conducted under temperature conditions close to practical storage environments, and key mechanical parameters including maximum tensile strength, maximum elongation and effective fracture energy were extracted. An exponential aging kinetics model incorporating time-stress coupling was developed, wherein the Zhukov relation was introduced to quantitatively describe the dependence of degradation rate on the applied stress level. The results indicate that, under high-stress conditions, the maximum tensile strength decreases to approximately 60% of its initial value within the first 10 days of aging, while the effective fracture energy drops to nearly one-third. In contrast, the degradation under low-stress conditions is significantly slower, demonstrating pronounced stress dependence and cumulative time effects. By further integrating finite element simulations of a vertically stored SRM, the Mises stress history along the liner propellant interface was extracted and coupled with the proposed aging model. The predicted safe storage life of the bonded interface is approximately 8.4 years. The proposed method enables quantitative characterization of interfacial aging behavior and provides a reliable basis for service life assessment, offering valuable guidance for structural safety analysis and storage reliability design of SRMs.

Key words: Solid rocket motor, Bonded interface, Aging, Peel test, Life assessment