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The MISSE 7 Flexural Stress Effects Experiment After 1.5 Years of Wake Space ExposureLow Earth orbit space environment conditions, including ultraviolet radiation, thermal cycling, and atomic oxygen exposure, can cause degradation of exterior spacecraft materials over time. Radiation and thermal exposure often results in bond- breaking and embrittlement of polymers, reducing mechanical strength and structural integrity. An experiment called the Flexural Stress Effects Experiment (FSEE) was flown with the objective of determining the role of space environmental exposure on the degradation of polymers under flexural stress. The FSEE samples were flown in the wake orientation on the exterior of International Space Station for 1.5 years. Twenty-four samples were flown: 12 bent over a 0.375 in. mandrel and 12 were over a 0.25 in. mandrel. This was designed to simulate flight configurations of insulation blankets on spacecraft. The samples consisted of assorted polyimide and fluorinated polymers with various coatings. Half the samples were designated for bend testing and the other half will be tensile tested. A non-standard bend-test procedure was designed to determine the surface strain at which embrittled polymers crack. All ten samples designated for bend testing have been tested. None of the control samples' polymers cracked, even under surface strains up to 19.7%, although one coating cracked. Of the ten flight samples tested, seven show increased embrittlement through bend-test induced cracking at surface strains from 0.70%to 11.73%. These results show that most of the tested polymers are embrittled due to space exposure, when compared to their control samples. Determination of the extent of space induced embrittlement of polymers is important for designing durable spacecraft.
Document ID
20170010654
Document Type
Presentation
Authors
Snow, Kate E. (Hathaway Brown School Shaker Heights, OH, United States)
De Groh, Kim K. (NASA Glenn Research Center Cleveland, OH, United States)
Banks, Bruce A. (Science Applications International Corp. Brook Park, OH, United States)
Date Acquired
November 7, 2017
Publication Date
July 17, 2017
Subject Category
Spacecraft Design, Testing and Performance
Structural Mechanics
Report/Patent Number
GRC-E-DAA-TN43558
Meeting Information
2017 International Space Station Research and Development (ISS R&D) Conference(Washington, DC)
Funding Number(s)
CONTRACT_GRANT: NNC12BA01B
WBS: WBS 934844.01.12.04.02
Distribution Limits
Public
Copyright
Public Use Permitted.

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