Shearographic nondestructive evaluation of Space Shuttle thermal protection systems

Christopher K. Davis; Jeffery A. Hooker; Stephen M. Simmons; Kenneth E. Tenbusch

doi:10.1117/12.213534

7 July 1995 Shearographic nondestructive evaluation of Space Shuttle thermal protection systems

Christopher K. Davis, Jeffery A. Hooker, Stephen M. Simmons, Kenneth E. Tenbusch

Proceedings Volume 2455, Nondestructive Evaluation of Aging Aircraft, Airports, Aerospace Hardware, and Materials; (1995) https://doi.org/10.1117/12.213534
Event: Nondestructive Evaluation of Aging Infrastructure, 1995, Oakland, CA, United States

Abstract

Preliminary results of shearographic inspections of the shuttle external tank (ET) spray-on foam insulation (SOFI) and solid rocket booster (SRB) Marshall sprayable ablative (MSA-2) epoxy-cork thermal protection systems (TPS) are presented. Debonding SOFI or MSA-2 damage the orbiter `belly' tile and exposes the ET/SRB to thermal loading. Previous work with the ET/SRB showed promising results with shearography. The first area investigated was the jack pad close-out, one of many areas on the ET where foam is applied at KSC. Voids 0.375 inch were detected in 1.75 inch thick foam using a pressure reduction of less than 0.4 psi. Of primary interest are areas of the ET that directly face the orbiter tile TPS. It is estimated that 90% of tile TPS damage on the orbiter `belly' results from debonding SOFI during ascent. Test panels modeling these areas were manufactured with programmed debonds to determine the sensitivity of shearography as a function of debond size, SOFI thickness and vacuum. Results show repeatable detection of debonds with a diameter approximately half the SOFI thickness at less than 0.4 psi pressure reduction. Preliminary results are also presented on inspections of MSA-2 and the remote manipulator system (RMS) honeycomb material.

Citation Download Citation

Christopher K. Davis, Jeffery A. Hooker, Stephen M. Simmons, and Kenneth E. Tenbusch "Shearographic nondestructive evaluation of Space Shuttle thermal protection systems", Proc. SPIE 2455, Nondestructive Evaluation of Aging Aircraft, Airports, Aerospace Hardware, and Materials, (7 July 1995); https://doi.org/10.1117/12.213534

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