고체추진제의 3차원 비선형 점탄성 구성방정식에 관한 연구

Abstract

A nonlinear viscoelastic constitutive model for the solid propellant is proposed. This model is extended to three-dimensional one from existing isotropic model which is verified in the one dimensional stress state. Large deformation, dewetting and cyclic loading effects are treated as main sources of nonlinear behavior of the solid propellant. The softening of the solid propellant due to dewetting is treated by the modulus decrease. The nonlinearities during cyclic loading are accounted for by functions of the octahedral shear strain measure. The constitutive equation is implemented into a finite element code for the analysis of propellant grains. A commercial finite element package ``ABAQUS`` is used for the analysis and the model is introduced into the code through a user subroutine. The model is evaluated with different loading conditions and the predicted values are in good agreement with the biaxial test results.