The Structural Integrity Analysis Of Solid Rocket Grains Bases On The Three-dimensional Viscoelastic Finite Element Method

In this paper, the structure integrity analysis of solid rocket grains is studied by the use of the three-dimensional linear viscoelastic finite element method, and the structure integrity of the solid rocket motor made of hydroxyl teminated polybutadiene propellant is analyzed.Because the solid propellant is a typical viscoelastic material, it is necessary for structure integrity analysis of solid propellant grains to use the viscoelastic mechanics mold. From the one-dimensional linear viscoelastic theory, the one-dimensional linear viscoelastic constitutive equations are summarized. Extending to three-dimension, the three-dimensional linear viscoelastic integral equations and the governing equations of 3D viscoelastic theory are got. Based on those works, the mechanical properties of solid propellant are studied, the viscoelastic poisson vatio,the stres s ralaxation modulus,the maximum unilateral tensile strength and elongation rate are obtained through tests, the stress relaxation modulus master curve,the maximum unilateral tensile strength master curv,the elongation rate master curve and their W. L. F. equations are also obtained on the basis of the temperature-time equivalence principle.After acquiring the mechanical properties of solid propellant, the numerical results of stress and strain about the solid rocket grain in the lowest temperature environment allowed are given by using FEM software MSC. Marc. Based on those results, the destroy analysis is carried out. Compared the numerical results with the experimental results, the relation of the maximum mechanical properties on the three-dimensional condition and the maximum unilateral tensile properties about the grain is abstained. It is of certain significance for the design and the structure integrity analysis of solid rocket grains.