Diagnostic Ultrasound for Structural Health in Solid Rocket Motor Components

The degradation of solid rocket motor components due to aging has a significant negative impact on mission success for both aerospace and military applications. Luna, in teaming with Aerojet, will assemble a specifications database including appropriate ranges of material properties and geometries of individual SRM components to help focus the efforts to relevant applications. Using Aerojet-supplied samples, Luna will apply its high resolution ultrasonic measurement capability for materials characterization of critical SRM components. Measurements of ultrasonic velocity and attenuation including stress/strain dependence will be made in order to assess shear and elastic moduli, as well as, third order elastic/viscoelastic properties. These measurements will be made under the context of their relationship with age related effects and become the foundation for the development of a numerical model of ultrasonic guided wave propagation in multilayer cylinders. This model will be used to optimize sensitivity and determine appropriate inspection parameters. Proof-of-concept testing on strain relief cylinders will evaluate this technique’s capability for assessing reduced modulus propellant and propellant-liner disbond in practically applicable samples. The results of this Phase I effort will lay the groundwork for a diagnostic measurement system capable of assessing the structural health of SRM components.