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2016
Conference Paper
Titel
Non-destructive ageing state determination of solid rocket motors charges
Abstract
Solid rocket motor propulsion is used for missiles, spacecrafts, space launch vehicles and gas-generators whenever high thrust, impulse and/or energy are needed in combination with a compact volume, high reliability and instantaneous readiness over a long service life. Solid rocket motors propellant charges for missiles are designed to withstand significant thermal and mechanical loads. Structural failure modes related to the charge are almost invariably catastrophic due to the large energy released by propellant combustion. Unfortunately, solid rocket motors have a finite life: propellant ageing due to chemical effects or mechanical damage limits their useful life. The complexity and hazard related to replacing the solid rocket motor, together with the cost of the motor itself, makes it a key factor in the life-cycle cost of tactical and strategic missiles. Motor ageing is driven by usage: chemical ageing occurs faster at higher temperature, mechanical damage depends on real load exposure. As a result, the condition of individual motors in the stockpile can be very different. In-service surveillance procedures during service life involve expensive destructive tests on a small number of motors. Extending few results to the entire missile stockpile involves the use of safety factors. In many cases, assets are disposed prematurely. Consequently, high-performance missiles procurement and maintenance involves a high yearly life-cycle cost because motors are disposed or replaced prematurely. This paper shows the feasibility of a new-non-destructive ageing state determination test for solid propellant charges, the first of its kind for this application. The method relies on stress and temperature sensors embedded in the propellant charge. It allows measuring the ageing state of the propellant charge, determining its safe remaining life, and measuring life consumption after a period of time during life. The economic and operational benefits for users seem significant.