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SRB frustrum 'smiley' cracking phenomenon studyThe thermal protection system installed on the SRB frustrums incurs the formation of debonds between the MSA-2 TPS material and the substrate. The debonds can lead to surface penetrating cracks, called 'smileys' near sealed fasteners and other surface discontinuities. The study concluded that the 'smileys' were caused as the result of stress risers caused by excess fastener sealant (PR-1422) and weakly bonded surfaces. Once the debond occurs, 'smileys' form when the debond area is sufficiently large. The loading for the debond and 'smiley' formation is seen to be depressurization at the vacuum conditions near the end of powered boost. The porous nature of the MSA-2 material covered by a vapor barrier paint provides internal pressure loading of the MSA-2 material. Recommendations for eliminating the problem include elimination of excess PR-1422 sealant and improved attention to bonding surface preparation.
Document ID
19930011723
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Cruse, Thomas A.
(Cruse (Thomas) Nashville, TN, United States)
Date Acquired
September 8, 2013
Publication Date
February 26, 1993
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
TAC-93-001
NAS 1.26:192522
NASA-CR-192522
Accession Number
93N20912
Funding Number(s)
CONTRACT_GRANT: NASA ORDER H-11992-D
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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