Modeling of crack initiation and growth in solid rocket propellants using macromechanics and micromechanics theories

Abstract

Modeling and simulation of crack initiation and propagation in solid rocket propellant materials were conducted using both the macromechanics approach and the micro/macromechanics approach. Due to their composition, the solid rocket propellant can be construed as particle reinforced composites. The macromechanics approach entailed a numerical simulation of a finite element model to predict the crack behavior based on the damage initiation, growth, and local saturation. Its results were then compared to the experimental data. In the simulation, it was assumed that a crack forms when a damage is saturated in a localized zone. The results from the simulation were quite comparable to the experimental results, validating the method of predicting crack initiation, growth, and arrest using the concept of damage growth and saturation. The second approach involved using a simplified micromechanical model and the damage mechanics being applied at the micromechanics level and the finite element analysis being done subsequently at the macromechanics level. In using this approach, the damage modes such as matrix cracking, interface debonding and particle cracking were explainable in an explicit fundamental manner. Several simulations were conducted using this approach including the cases of non- uniform particle distribution. The predicted results compared well with the experimental data.