CUMMULATIVE DAMAGE RULE APPLICATION IN SOLID ROCKET MOTOR SERVICE LIFE  PREDICTION

RADUN JEREMIĆ

Military Academy, Belgrade, radun@mail.com

Nikola GligorijeviĆ

Military Technical Institute, Belgrade, nikola.gligorijevic@gmail.com

VESNA RODIĆ

Military Technical Institute, Belgrade, vesna_rodic@vektor.net

SREDOJE SUBOTIĆ

Military Technical Institute, Belgrade, sredoje.subotic@gmail.com

RADENKO DIMITRIJEVIĆ

Military Academy, Belgrade, radenkod@beotel.rs

SAŠA ŽIVKOVIĆ

Military Technical Institute, Belgrade, sasavite@yahoo.com

Abstract: Linear cummulative damage rule is  found to be useful in the solid propellant case-bonded grain service life prediction. A number of a HTPB composite propellant specimens were exposed to different constant stress levels. Times required to produce failure were measured. It has been confirmed that a power function is useful to describe the relationship between applied stresses and reduced times to failure. During a new rocket motor design, the cummulative damage law  for a new propellant is not known, and the calculations with the purpose to estimate the service life are not possible before the long time experiments were evaluated. A new simple rule has been indicated through the cummulative damage experiments, and it makes possible to get an approximation during a preliminary structural analysis, using the propellant initial strength results.