Reliability Analysis of a Solid Rocket Motor Based on Response Surface Method and Monte Carlo Simulation

*† ‡ § Determination of the reliability of rocket motors is generally a difficult task because of its cost and the safety requirements during testing. In general, real time testing of a solid rocket motor to demonstrate a high reliability is impossible when the costs of manufacturing and testing are concerned and because of the destruction on the rocket motor components during the operation, it is also difficult to perform failure analysis for individual components. Because of the difficulties in demonstrating reliability by testing, other approaches to determine the reliability of the components/system should be used during the early stages of the design. In this study, Monte Carlo Simulation is used to predict Solid Rocket Motor (SRM) reliability and for the cases where performance function can not be expressed by known formulas, Response Surface Method is utilized. Performance requirements including ballistic performance and structural safety are defined for reliability calculations. Geometrical variations such as throat diameter, burning area, port area and propellant ballistic properties are considered for Monte Carlo simulations and response surface computations. Structural reliability of the motor case is also determined. Effectiveness and weakness of Response Surface method is discussed. Sensitivities of performance parameters with respect to geometrical properties of the motor and ballistic properties of the propellant are established. Numerical results are given for 71 mm unguided rocket motor.