Modified cumulative damage model of composite propellants based on thermal aging mechanisms

This study proposes a modified cumulative damage model for GAP-based composite solid propellants, considering thermal aging effects. Accelerated thermal aging experiments were conducted at 333.15 and 343.15 K to analyse the variations in mechanical properties, including elastic modulus and maximum elongation. The results revealed an approximately 15% increase in elastic modulus and an approximately 25% decrease in maximum elongation during 333.15 K thermal aging. Based on the Arrhenius equation, a predictive model for mechanical parameter degradation was established, and the evolution of cumulative damage parameters was simplified using three assumptions. The modified model, accounting for aging effects on parameter β, demonstrated good agreement with direct computational results. Numerical simulations indicated that aging substantially amplifies cumulative damage in solid rocket motors under thermal cycling loads. This research provides a theoretical framework for assessing the structural integrity of solid rocket motor during long-term storage.