Numerical analysis on large deformation of propellant grains for solid rocket motors

Near-incompressibility and nonlinearity of propellant grains for solid rocket motors were considered. Based on incompressible viscoelastic constitutive relationship and virtual work equation of total Lagrangian, a two-dimensional viscoelastic geometry nonlinear finite element incremental relationship was derived. Finally finite element program was complied and its results were compared with that of calculation case, in addition, structure of star-shaped grain under the pressure load was analyzed. The results show that the approach and program are valid for stress analysis of viscoelastic materials with all admissible values of Poisson's ratio and particularly for stress analysis of solid propellant grains.