The Space Shuttle Columbia's catastrophic failure is thought to have been caused by a dislodged piece of external tank spray on foam insulation (SOFI) striking and significantly damaging the left wing of the orbiter, which may have been due to a flawed section of SOFI. Microwave and millimeter wave nondestructive evaluation (NDF) methods have shown great potential detecting anomalies in SOFI such as small air voids using a horn and lens in a (real) focused configuration. Synthetic focusing methods may also be used to detect air voids in SOFI and may additionally offer the ability to locate the defect in three dimensions. To this end, two different methods were investigated; namely, frequency domain synthetic aperture focusing technique (FD-SAFT) and wide-band microwave holography. To illustrate the performance of these methods they were applied to two different SOFI samples. The results of these investigations demonstrate the capabilities of these methods for SOFI inspection
J. T. Case et al., "Inspection of Spray on Foam Insulation (SOFI) Using Microwave and Millimeter Wave Synthetic Aperture Focusing and Holography," Proceedings of the IEEE Instrumentation and Measurement Technology Conference, 2006, Institute of Electrical and Electronics Engineers (IEEE), Apr 2006.
The definitive version is available at http://dx.doi.org/10.1109/IMTC.2006.328527
IEEE Instrumentation and Measurement Technology Conference, 2006
Electrical and Computer Engineering
Marshall Space Flight Center
United States. National Aeronautics and Space Administration
Keywords and Phrases
Flaw Detection; Foams; Microwave Holography; Millimetre Wave Imaging; Space Vehicles Voids (Solid)
Article - Conference proceedings
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