Effect of Ageing on Structural Integrity of a Composite HTPB Solid Propellant Rocket Motor Grain
Ageing of solid propellants in a broad sense is the deterioration of mechanical properties during storage, resulting changes in performance of the solid propellant rocket motors. The ageing of composite propellant grains is very complex. Changes in the initial properties of the propellant occur due to a combination of the damage caused by physical ageing together with chemical processes in the propellant. Margins of safety evaluated using initial mechanical properties with knockdown or knockup factors might not reflect the true nature of these combined effects. This paper examines the effect of ageing on the structural integrity of a composite HTPB solid propellant rocket motor grain of 1m diameter having star cross-section under thermal shrinkage and internal pressure loading conditions. A complex 3D geometric model of the propellant grain configuration is generated and performed the finite element analysis utilizing the MARC software. The maximum induced thermal and pressure load related strains along the inner port of the grain and principal stresses along the propellant /insulation interface are determined for margin evaluation by comparing with allowable values of elongation and bond strength. HTPB propellant mechanical properties at the normal strain rate for different time instants are evaluated and determined the ageing rate constant K in the Arrhenius equation. A segment was dissected to evaluate the mechanical properties of main motor, which are comparable with those of the Carton samples. The mechanical properties evaluated at the higher strain rate corresponding to the ignition pressure enhance the margins.
RENGANATHAN K. SARMA B.S.V.Rama RAO B.Nageswara SIVASUBRAMONIAN B. NAIR N.Jayachandran
Structural Engineering Entity, Vikram Sarabhai Space Centre, Trivandrum-695022, India
国际会议
2011 International Autumn Seminar on Propellants,Explosives and Pyrotechnics(2011国际推进剂、炸药、烟火技术秋季研讨会)
南京
英文
210-220
2011-09-20（万方平台首次上网日期，不代表论文的发表时间）