Description: Damage caused by composite overwrapped pressure vessels (COPVs) failure can be catastrophic. Thus, monitoring condition and stress in the composite overwrap, including the fiber layers most prone to failure is needed during both preflight qualification and spaceflight. We will develop practical Non-destructive Evaluation (NDE) capability for use during spaceflight and surface mounted magnetic stress gages (MSGs) for preflight qualifications/testing and in-flight monitoring. NDE will address damage produced by impacts from micro-meteoroid orbital debris (MMOD). In addition, we will investigate the need to inspect through multi-layer insulation layer (MLI). The goal is to demonstrate feasibility of (i) volumetric stress monitoring using light weight, surface mounted MSGs, and (ii) practical, portable and easy to interpret NDE for use by crews during spaceflight, with limited training and minimal logistics support. Dual purpose electronics will be adapted to the constraints of spaceflight for NDE and MSG data acquisition and the feasibility of developing extremely light weight and small form factor electronics suitable for space flight will be investigated. This proposal is founded on successful implementations of JENTEK MWM-Array technology for the Space Shuttle leading edge RCC and recent feasibility demonstrations for MSG volumetric stress monitoring on COPV sections. The MWM-Arrays and MSGs use linear drive winding constructs to selectively induce eddy currents in different fiber layers to assess damage and monitor stresses.

Benefits: Enhanced inspection required for qualification testing are needed for widely used gas cylinders and other pressure vessels used throughout industry. Stress monitoring during COPV operation will enhance life management capabilities. Composite SCBA tanks that are widely used by fire and rescue personnel are currently limited to a 15 year life from date of manufacture by the department of transportation. This restriction is partly due to the fact take there is no accepted method to characterize damage in composite SCBA tanks. If this project is successful the techniques developed in it can be adapted to composite SCBA tanks to provide reliable damage assessment of these cylinders. Furthermore, composites are seeing widespread use for repairs of pressurized pipelines and other infrastructure; thus, we anticipate broad commercial opportunities in transportation and other sectors.

If this project is successful, an enhanced inspection capability will become available to NASA that will support improved life management of COPVs. Improved NDE of COPVs was identified in the 2008 KSC High Priority Technology Needs. NDE and stress monitoring during spaceflight with a minimal logistics footprint would enhance flight safety and provide capability for in-flight condition assessment, mission adaptations, and maintenance. Furthermore, this capability can support NDE and stress monitoring for other composite structures of interest to NASA.