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Fracture Mechanics Testing of Titanium 6AL-4V in AF-M315EThe Green Propellant Infusion Mission (GPIM) will demonstrate the performance of AF-M315E monopropellant on orbit. Flight certification requires a safe-life analysis of the titanium alloy fuel tank to ensure inherent processing flaws will not cause failure during the design life of the tank. Material property inputs for this analysis require testing to determine the stress intensity factor for environment-assisted cracking (KEAC) of Ti 6Al-4V in combination with the AF-M315E monopropellant. Testing of single-edge notched, or SE(B), specimens representing the bulk tank membrane and weld material were performed in accordance with ASTM E1681. Specimens with fatigue pre-cracks were loaded into test fixtures so that the crack tips were exposed to AF-M315E at 50 C for a duration of 1,000 hours. Specimens that did not fail during exposure were opened to inspect the crack surfaces for evidence of crack growth. The threshold stress intensity value, KEAC, is the highest applied stress intensity that produced neither a failure of the specimen during the exposure nor showed evidence of crack growth. The threshold stress intensity factor for environment-assisted cracking of the Ti 6Al-4V forged tank material was found to be at least 22 ksi√in and at least 31 ksi√in for the weld material when exposed to AF-M315E monopropellant.
Document ID
20160006338
Acquisition Source
Kennedy Space Center
Document Type
Conference Paper
Authors
Sampson, J. W.
(NASA Kennedy Space Center Cocoa Beach, FL United States)
Martinez, J.
(NASA Kennedy Space Center Cocoa Beach, FL United States)
McLean, C.
(Ball Aerospace and Technologies Corp. Boulder, CO, United States)
Date Acquired
May 17, 2016
Publication Date
May 16, 2016
Subject Category
Metals And Metallic Materials
Aircraft Design, Testing And Performance
Report/Patent Number
KSC-E-DAA-TN31582
Meeting Information
Meeting: JANNAF Propulsion Meeting
Location: Newport News, VA
Country: United States
Start Date: May 16, 2016
End Date: May 19, 2016
Sponsors: Department of the Army, NASA Goddard Space Flight Center, Department of the Navy, Department of the Air Force
Funding Number(s)
CONTRACT_GRANT: NNM12AA79C
WBS: WBS 878336.01.06
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
AF-M315E
Ti 6Al-4V
monopropellant
titanium 6Al-4V
Stress intensity threshold
Environment-Assisted Cracking
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