Three-dimensional photoelastic and finite-element analysis of a propellant grain

The results of a three-dimensional photoelastic analysis of a propellant-grain model are compared with the results obtained from a three-dimensional finite-element analysis of the same model. The loading considered was differential thermal expansion between the case and the grain model. The model analyzed was the Stage I Minuteman propellant grain which consists of a six-point-star configuration with a head-end web. Stresses and strains determined from the two analyses in the star valley are compared. The excellent correlation between the stresses determined from the photoelastic analysis and the stresses calculated by the three-dimensional finite-element computer program established the validity of the computer program.