Prediction Method of Heterogeneous Propellant Relaxation Moduli Based on Viscoelastic VCFEM

The relaxation modulus of heterogeneous propellants permits evaluating the structural integrity and life of a solid rocket motor. Its governing factors were investigated by the Voronoi cell finite element method (VCFEM) at the microscopic level. The formula of viscoelastic VCFEM is based on the discrete form of the Prony series viscoelastic constitutive model in the time domain; the iterative procedure is also proposed to obtain the effective modulus at each time step. The random sampling method is adopted to analyze the effect of each microparameter on the effective relaxation modulus. The results show that the matrix modulus and inclusion weight fraction exert a more pronounced effect on the relaxation modulus than the inclusion material constants and particle grain.