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Designing of a Fleet-Leader Program for Carbon Composite Overwrapped Pressure VesselsComposite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases on board spacecraft when mass saving is a prime requirement. Substantial weight savings can be achieved compared to all metallic pressure vessels. For example, on the space shuttle, replacement of all metallic pressure vessels with Kevlar COPVs resulted in a weight savings of about 30 percent. Mass critical space applications such as the Ares and Orion vehicles are currently being planned to use as many COPVs as possible in place of all-metallic pressure vessels to minimize the overall mass of the vehicle. Due to the fact that overwraps are subjected to sustained loads during long periods of a mission, stress rupture failure is a major concern. It is, therefore, important to ascertain the reliability of these vessels by analysis, since it is practically impossible to show by experimental testing the reliability of flight quality vessels. Also, it is a common practice to set aside flight quality vessels as "fleet leaders" in a test program where these vessels are subjected to slightly accelerated operating conditions so that they lead the actual flight vessels both in time and load. The intention of fleet leaders is to provide advanced warning if there is a serious design flaw in the vessels so that a major disaster in the flight vessels can be averted with advance warning. On the other hand, the accelerating conditions must be not so severe as to be prone to false alarms. The primary focus of the present paper is to provide an analytical basis for designing a viable fleet leader program for carbon COPVs. The analysis is based on a stress rupture behavior model incorporating Weibull statistics and power-law sensitivity of life to fiber stress level.
Document ID
20090039962
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Murthy, Pappu L.N. (NASA Glenn Research Center Cleveland, OH, United States)
Phoenix, S. Leigh (Cornell Univ. Ithaca, NY, United States)
Date Acquired
August 24, 2013
Publication Date
October 1, 2009
Subject Category
Composite Materials
Report/Patent Number
AIAA Paper 2009-2517
E-17057
NASA/TM-2009-215685
Meeting Information
Meeting: 50th Structures, Structural Dynamics, and Materials Conference
Location: Palm Springs, California
Country: United States
Start Date: May 4, 2009
End Date: May 7, 2009
Sponsors: American Helicopter Society, Inc., American Society of Civil Engineers, American Inst. of Aeronautics and Astronautics, American Society of Mechanical Engineers
Funding Number(s)
WBS: WBS 869021.03.03.02.01
Distribution Limits
Public
Copyright
Public Use Permitted.

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