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Alternate Methods in Refining the SLS Nozzle Plug LoadsNumerical analysis has shown that the SLS nozzle environmental barrier (nozzle plug) design is inadequate for the prelaunch condition, which consists of two dominant loads: 1) the main engines startup pressure and 2) an environmentally induced pressure. Efforts to reduce load conservatisms included a dynamic analysis which showed a 31% higher safety factor compared to the standard static analysis. The environmental load is typically approached with a deterministic method using the worst possible combinations of pressures and temperatures. An alternate probabilistic approach, utilizing the distributions of pressures and temperatures, resulted in a 54% reduction in the environmental pressure load. A Monte Carlo simulation of environmental load that used five years of historical pressure and temperature data supported the results of the probabilistic analysis, indicating the probabilistic load is reflective of a 3-sigma condition (1 in 370 probability). Utilizing the probabilistic load analysis eliminated excessive conservatisms and will prevent a future overdesign of the nozzle plug. Employing a similar probabilistic approach to other design and analysis activities can result in realistic yet adequately conservative solutions.
Document ID
20130013955
Document Type
Conference Paper
Authors
Burbank, Scott (ATK Aerospace Systems Brigham City, UT, United States)
Allen, Andrew (ATK Aerospace Systems Brigham City, UT, United States)
Date Acquired
August 27, 2013
Publication Date
April 24, 2013
Subject Category
Spacecraft Propulsion and Power
Report/Patent Number
M13-2597
Meeting Information
ATK Internal Conference(Ogden, UT)
Funding Number(s)
CONTRACT_GRANT: NNM07AA75C
Distribution Limits
Public
Copyright
Public Use Permitted.

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