Multiscale viscoelastic constitutive modeling of solid propellants subjected to large deformation

This paper develops a multiscale nonlinear viscoelastic constitutive model for the Nitrate Ester Plasticized Polyether (NEPE) propellant with high elongation. The proposed model considers viscoelasticity, strain rate, confining pressure, and softening effects. The macroscopic damage due to interface debonding or failure in the matrix itself is investigated by capturing the microstructural changes in a representative volume element (RVE). To account for the evolution of interface debonding, a physics-based normalized debonding ratio is introduced and modeled using a cohesive zone model (CZM). As the damage functions are obtained from the RVE, decoupled calibration of the material parameters is possible. The model is then programmed into ABAQUS via a subroutine for numerical analysis. The effects of strain rate, multi-step relaxation, creep, and confining pressure on the stress response are presented. Overall, the predicted results are in good agreement with the experiments.

Automated summary

This paper presents a multiscale nonlinear viscoelastic constitutive model for NEPE propellant with high elongation, taking into account viscoelasticity, strain rate, confining pressure, and softening effects. The damage due to interface debonding or failure is investigated by analyzing microstructural changes in an RVE. A physics-based normalized debonding ratio is introduced and modeled using a cohesive zone model to capture the evolution of interface debonding. The model is implemented in ABAQUS for numerical analysis and shows good agreement with experimental results, considering the effects of strain rate, relaxation, creep, and confining pressure on stress response.