Viscoelastic debonding criterion-based interface for modeling the mechanical behavior of solid propellants subjected to large deformation

Introducing new energetic particles into the solid propellants for improving their power performance may result in unsatisfactory mechanical responses. The current contribution aims to understand better the link between macroscopic mechanical behaviours and microstructural changes of a novel high elongation (>100%) Nitrate Ester Plasticized Polyether (NEPE) propellant using a computational representative volume element (RVE) containing a viscoelastic debonding criterion-based interface. The stress-strain responses and microstructural damage evolutions predicted at different strain rates agree reasonably well with the experiments. Results indicate that strain rate influences the local damage, and the particle size is not more critical than the interfacial properties for the appearance of interface debonding in the propellant with various types of fillers. Damage mechanisms and mechanical response under tensile and compressive loadings are discussed together with the impacts of damage in the matrix itself. While the damage in tension is characterized by amounts of interface debonding, fibrillar matrix, cavities and catastrophic cracks orthogonal to the loading direction, the microstructural damage in compression features in-layer tearing fracture, which is almost inclined at 45° to the loading direction, with relatively few damaged interfaces. Besides, the stress-strain response is slightly affected by matrix damage in the case of tensile loading but significantly influenced under compression.