Quantitative Propellant Diagnostics with Ultrasonic Guided Waves

Given their polymeric and viscoelastic nature, solid propellants are subject to various aging effects that may lead to failure of the asset.  Many of these aging effects relate back to degradation or variation in material properties/behavior over time.  Luna proposes to address this issue with an ultrasonic guided wave approach capable of extracting engineering properties from portions of the propellant requiring only access to the outer surface of the case.  In Phase I, Luna plans to address several key factors for determining feasibility of the proposed approach.  Luna will measure bulk ultrasonic properties in propellant simulants provided by Aerojet at various stages of aging.  Mechanical test specimens will be prepared to validate links between ultrasonic measurement and engineering properties.  An initial two-layer mockup will be prepared to show connection between ultrasonic guided wave measurement and bulk ultrasonic properties.  Connections between viscoelastic properties and aging effects within solid rocket propellants will also be explored.  Successful outcomes from these four Phase I focus areas will help address high technical risks early in the program .  These results are also fundamental in shaping the roadmap and framework for a continuing program to transition from measurement to practical instrument. BENEFITS: By partnering with Aerojet, Luna will be able to mature this collaboration into a potential business relationship with a prime contractor in this field.  Luna aims to couple these developments with other solid rocket motor diagnostic efforts for a broader suite of measurement capability tied to mission critical assets providing a significant cost reduction to both military and aerospace entities by eliminating access maintenance and limit premature removal from service.  Luna can leverage the developments under this program to further enhance the capability of its pre-existing Nondestructive Checkout Center (NCC) (an NDI and material characterization system developd for the DOD under a separate program) by providing that proof-of-concept system with a capability to assess more complex geometries and materials.  This enhancement can greatly enhance the marketability of that system while that system provides a tangible manifestation of the proposed measurement approach.