3-d Viscoelastic Random Analysis Of Grain For Solid Rocket Motor
- Paper ID
7050
- author
- company
Beijing University of Aeronautics and Astronautics
- country
China
- year
2007
- abstract
Structure integrity of solid propellant grain is a very important issue for department of design, manufacturing and application of solid racket motor. To analyze structure integrity of solid grain, structure and material parameters must be known. However, solid propellant is one type of viscoelastic macromolecule polymer material; its performance parameters always are dispersive. In addition, complex structure figure of grain and diversified outer load often has random characteristics. In traditional design methods, the randomness of these parameters is not taken into consideration, but taking these parameters as confirmed quantity. Only an experimental safety factor is used to describe possible influence of the randomness to product’s reliability. As the promotion of calculation precision, continue using traditional safety factor will cause mismatch of precision. Thus, the randomness in all factors which affect structure intensity needs to be considered in design and structure analysis. In recent years, for the promotion of calculation ability, as well as to describe real condition of engineering structure, it is a trend to consider uncertain factor. To do this, Monte Carlo method is often employed to simulate directly, but its disadvantage is that it needs a very high computational complexity. As the introduction of viscoelastic random FEM, computational efficiency has been increased largely. At present, random structure analysis of grain is still in elementary phase, research about it mainly focus on performance and analysis of 2-D simple structure of grain. For the randomness and complexity of 3-D structure, computational complexity in random structure analysis of 3-D grain has increased largely. There are few relevant reports at present. In this paper, for the randomness in the structure analysis of the grain, on the basis of incompressible viscoelastic incremental FEM and random FEM, with local averaging to discretize the random field, a 3-D viscoelastic random FEM is deduced and described. The influences of Poisson ratio, modulus and correlative structure model are studied. Additionally, the influences of more random variables together are studied. The results indicate that the influence of Poisson ratio is more important, which provide valuable reference to grain design.