Fiber Breakage Model for COPV Reliability Estimation
Volume 9, Number 6, November 2013 - Paper 06 - pp. 641-655
RICHARD P. HEYDORN1, and PAPPU L. N. MURTHY21 JSC Safety and Mission Assurance, Analysis Branch
2 GRC Structures and Materials, Life Prediction Branch
(Received on February 02, 2013, revised on April 02, May 01, and May 23, 2013)
The most commonly used reliability model to predict the probability of a COPV rupture is based on the Weibull distribution. In this paper we propose an alternative reliability model based on the idea that the stress rupture process is preceded by the formation and evolution of fiber breakage clusters. The fiber breaks in this process are described by a Bose-Einstein distribution which leads to a Polya urn model that describes the progression of the number of fiber breaks. This urn model shows that two distinct paths for the formation of breakage clusters are possible. In the first one a few breakage clusters are shown to have a dominant number of breaks. In the second one, the breakage clusters are shown to have the number of breaks evenly distributed across clusters. Simulations suggest that the dominant case leads to a high variance across the total number of breaks, whereas the evenly distributed case leads to a smaller variance. A small number of clusters will lead to fiber breakage reliability models that estimate a higher reliability than does the Weibull.
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