Analysis of the stress state of solid propellant grains under internal pressure load

Abstract

In order to determine the stress state of the solid rocket motor grain under the internal pressure load, based on the finite element numerical simulation calculation, the length and size requirements of the grain under the internal pressure simplified to a plane strain problem are obtained. Numerical simulation calculations are further carried out for the grains in plane strain state that meet the simplified conditions, and the radial and circumferential stress states of the grains are obtained. The numerical simulation results are compared with the viscoelastic theoretical solution of the grains under the same material parameters. The results show that when the aspect ratio exceeds 2.5, the axial strain is approximately 0, which can be equivalent to a plane strain problem. In addition, the analysis shows that under the action of internal pressure, the plane strain grains are in a bidirectional compression stress state with a radial and circumferential stress ratio of approximately 1:1. Finally, by comparing the numerical solution and the analytical solution, it is found that the relative error is within 3%, which verifies the correctness of the numerical simulation calculation results.