REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

AN EXAMPLE OF PROPELLANT GRAIN STRUCTURAL ANALYSIS UNDER THE THERMAL AND ACCELERATION LOADS

SAŠA ANTONOVIĆ

Military Technical Institute, Rocket Armament Sector, Belgrade, saleantonovic82@gmail.com

Nikola GLIGORIJEVIĆ

Military Technical Institute, Rocket Armament Sector, Belgrade, nikola.gligorijevic@gmail.com

ALEKSANDAR MILOJKOVIĆ

Military Technical Institute, Sector for Materials and Protection, Belgrade, aleksandar.milojkovic@gmail.com

SREDOJE SUBOTIĆ

Military Technical Institute, Rocket Armament Sector, Belgrade, sredoje.subotic@gmail.com

SAŠA ŽIVKOVIĆ

Military Technical Institute, Rocket Armament Sector, Belgrade, sasavite@yahoo.com

BOJAN PAVKOVIĆ

Military Technical Institute, Rocket Armament Sector, Belgrade, bjnpav@gmail.com

Abstract:  In the design phase of a rocket motor propellant grain for an anti-armor artillery rocket, the problem of high stresses and strains due to temperature and acceleration has been considered. Complete mechanical characterization for a new composite propellant composition is very expensive and takes a long time. Therefore it is usually not done before the propellant composition completely meets the ballistic requirements of the new rocket motor. In the initial stage, the measurements of the mechanical properties are performed only in standard conditions, but these data are not sufficient for reliable analysis. Composite rocket propellant is a viscoelastic material whose mechanical properties depend on temperature and strain rate and vary in the range of several orders of magnitude. The lack of data required for a reliable analysis is compensated by using the known data of a similar composite propellant composition. In the MTI database, for this similar propellant composition there exists a data colection for the complete mechanical characterization. A method of comparison and extrapolation has been used. Finally, quasi-viscoelastic analysis was performed for different design solutions, using the finite element method.

Keywords: Propellant Grain, Thermal Load, Acceleration, Viscoelasticity, Mechanical Characterization.