Structural integrity under inertia loading was considered to be one of the design conditions for a solid propellant rocket motor. Grain structural integrity evaluations were generally based upon mechanical properties which were evaluated from tests of specimens removed from carton samples of propellant. Significant deviations were noticed while testing specimens from carton samples and from dissecting grains due to manufacturing process. Main grain to carton correlation factors established for a HTPB-based propellant and their adequacy examined measuring slumps in cylindrical grain segments. A simple methodology presented to carryout viscoelastic finite element analysis for slump estimations in rocket grains under vertical storage condition. Finite element analysis was carried out on a cylindrical segment grain of a typical steel casing rocket motor using the eight-node quadrilateral axi-symmetric Hermann element of the MARC computer program. A mathematical model proposed to represent the time dependent master stress relaxation modulus of a HTPB-based propellant grain essential for estimation of slump displacements in cast segment grains. Measured slump displacements in rocket motors of different segment grains at different storage times were found to be reasonably in good agreement with the finite element analysis results.
K. Renganathan, B. Nageswara Rao and M.K. Jana , 2006. Slump Estimation of Cylindrical Segment Grains of a Typical Rocket Motor under Vertical Storage Condition. Trends in Applied Sciences Research, 1: 97-104.