Fractal dimension-based damage characterization of solid propellant under different loading conditions

The long-term storage and service of solid rocket propellants can lead to microstructural changes that significantly impact their combustion performance and reliability. Understanding and quantifying this damage is crucial for ensuring the safety and extends the service life of aerospace propulsion systems. Existing methods often lack a comprehensive quantitative approach for characterizing complex surface damage. In this study, a novel quantitative analysis method is proposed, integrating image processing and fractal dimension analysis to characterize the surface damage of solid propellants. This approach leverages high-resolution scanning electron microscopy (SEM) images and the box-counting method for fractal dimension calculation. This method provides a powerful and versatile tool for evaluating the extent of surface microstructural degradation. Experimental results demonstrate that the fractal dimension, serving as a robust indicator of surface damage, increases with rising temperature (from 1.5260 at 50°C to 1.5772 at 70°C), longer aging durations (from 1.5772 at 7 days to 1.6391 at 21 days) , and greater pre-strain levels (from 1.6391 at 6% to 1.6657 at 12%). These findings offer valuable insights for service life assessment and damage prediction of solid propellants, contributing significantly to the fields of aerospace materials science, non-destructive evaluation, and propulsion system reliability.