Analysis of effect of the pad material on stress in the grain during launching artillery missile

Three-dimensional visco-elastic large deformation incremental constitutive equation was derived based on total Lagrangian method. The stress distribution in the grain during launching was simulated numerically by finite element method under axial highly accelerated condition for solid rocket motor. The influences of pad material, pad thickness, and load abidance time on the stress in the grain were analyzed. The analyzed results show that the equivalent stresses in the grain decrease with the increase of Poisson ratio of the pad material; equivalent stresses in the grain increase slightly with the increase of elastic modulus when Poisson ratio is less that 0.49, and equivalent stress in the grain decreases first, increases slightly then with the increase of elastic modulus when Poisson ratio is equal to 0.49; the maximum stress in the grain decreases with the increase of the pad thickness; influence of load abidance time on equivalent stress in the grain is not evident after reaching steady load.