# Mesoscale Damage Evolution, Localization, and Failure in Solid Propellants Under Strain Rate and Temperature Effects

## TL;DR

This paper studies how solid rocket propellants break under high-speed stress and temperature changes, using a new modeling approach.

## Contribution

A cohesive finite element method framework is developed to quantify thermomechanical responses at the microstructural scale.

## Key findings

- Damage evolution in propellants is strongly influenced by strain rate and temperature.
- The proposed CFEM model accurately predicts damage progression and mechanical responses.
- Neural network-based methods improve parameter identification for cohesive models.

## Abstract

High-energy solid propellants are multiphase engineering materials, whose mechanical behavior is predominantly governed by the characteristics of embedded crystalline particles. While microstructural influences have been extensively examined, quantitative correlations between microstructure and macroscopic mechanical properties remain underexplored. This work develops a cohesive finite element method (CFEM) framework to quantify the thermomechanical response of high-energy solid propellants at the microstructural scale. The analysis focuses on impact loading at strain rates ranging from 103 to 104 s−1, accounting for large deformation, thermomechanical coupling, and microcrack-induced failure. Damage evolution under impact conditions was evaluated using a combined neural network-based inverse identification method and a three-dimensional cohesive finite element model to determine temperature-dependent bilinear-polynomial cohesive parameters. Results demonstrate a strong dependence of the propellant’s mechanical behavior on both strain rate and temperature. Validation against experimental data confirms that the proposed temperature-sensitive CFEM accurately predicts both damage progression and macroscopic mechanical responses.