Nondestructive In-Situ Examination of Solid Rocket Motor Propellant Using Induced Positron Technology

Abstract

Failure of solid rocket motor propellants due to structural or chemical breakdown from manufacturing or aging effects can result in failure of the rocket and may require significant surveillance and maintenance requirements to assure operational readiness. Defects and aging effects in rocket propellants are significant issue s particularly for new propellants, which may suffer from short experiential histories, frequently unknown lifecycle parameters, and the inability of current non -destructive inspection techniques to detect damage (other than gross cracking) in these material s. Grain cracking and dewetting are significant propellant problems, which result from strain -induced damage in the solid rocket motor propellant and are undetectable by current nondestructive inspection methods. An inspection technology that is capable o f accurately, reliably, and nondestructively measuring strain and dewetting effects in advanced propellants through the outer rocket casing is needed for the purpose of assessing operational readiness for all solid rocket motors. New technologies that indu ce positrons inside the material to be characterized have demonstrated capabilities in non destructively measuring material damage in many material types. Damage assessment of solid rocket fuel propellant through the outer missile shell has been demonstrate d and indicate s that accurate and reliable evaluations of component readiness, either at the manufacturing level or during field inspections can be performed. The feasibility assessment discussed here demonstrated that empirical data on solid rocket propel lant strain buildup and grain cracking can be generated using the induced positron technologies, which can be used with confidence for assessing the damage state and mission readiness of advanced propellant or similar materials.