Study on a damage model of NEPE solid propellant based on a Weibull distribution

In this paper, the Weibull distribution function was used to describe the mechanical behavior of damage evolution and a new type of nonlinear viscoelastic constitutive model was established. Based on the results of a relaxation test and a uniaxial tensile test of NEPE propellant, the parameters of this model were fitted. The accuracy of the model was verified by comparing the predictive results and the experimental results. The UMAT subroutine was developed based on the Fortran code, and it was applied to simulate a uniaxial tensile model and a biaxial tensile model in ABAQUS. The finite-element calculated solutions are in good agreement with the experimental values, which proves that the subroutine is effective and the Mises equivalence criterion is applicable to NEPE solid propellant.