A fully-coupled mechanics and regression model for deflagration of solid composite propellants with realistic microstructure

Abstract

Solid Composite Propellants (SCPs) are widely employed in the field of propulsion due to their enduring chemical and mechanical stability during extended periods of storage, as well as their uncomplicated production and reliable performance. Unlike liquid propellants, solid propellants are self-supporting, meaning that that they function as structural materials as well as energetic. Consequently, it is essential to understand the mechanical behavior of SCPs during deflagration, as structural failure can have potentially catastrophic consequences. SCP failure is often associated with the formation and growth of micromechanical damage sites due to thermal and mechanical loads during burning. Thus, the ability to simulate stress propagation during the burning process is a key feature for the effective design and safe use of SCPs. The ability to evaluate failure in aged propellants and of those produced using additive manufacturing is of special interest. In this work, we present an elasticity solver coupled with a thermal phase-field model of regression of SCPs. Our model implements a unique strong-form solver for finite deformation material response, featuring block structured adaptive mesh refinement techniques and a multigrid solver. The model is first tested with simple tension-compression and is then expanded for the simulation of packed AP spheres in an HTPB binder matrix. Overall, it is determined that the model’s prediction of stress and strain fields and stress concentrations, yielding insight into the interplay between mesostructure and mechanical damage propensity.