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Probabilistic evaluation of uncertainties and risks in aerospace componentsThis paper summarizes a methodology developed at NASA Lewis Research Center which computationally simulates the structural, material, and load uncertainties associated with Space Shuttle Main Engine (SSME) components. The methodology was applied to evaluate the scatter in static, buckling, dynamic, fatigue, and damage behavior of the SSME turbo pump blade. Also calculated are the probability densities of typical critical blade responses, such as effective stress, natural frequency, damage initiation, most probable damage path, etc. Risk assessments were performed for different failure modes, and the effect of material degradation on the fatigue and damage behaviors of a blade were calculated using a multi-factor interaction equation. Failure probabilities for different fatigue cycles were computed and the uncertainties associated with damage initiation and damage propagation due to different load cycle were quantified. Evaluations on the effects of mistuned blades on a rotor were made; uncertainties in the excitation frequency were found to significantly amplify the blade responses of a mistuned rotor. The effects of the number of blades on a rotor were studied. The autocorrelation function of displacements and the probability density function of the first passage time for deterministic and random barriers for structures subjected to random processes also were computed. A brief discussion was included on the future direction of probabilistic structural analysis.
Document ID
19940005906
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Shah, A. R. (Sverdrup Technology, Inc. Cleveland, OH., United States)
Shiao, M. C. (Sverdrup Technology, Inc. Cleveland, OH., United States)
Nagpal, V. K. (Sverdrup Technology, Inc. Cleveland, OH., United States)
Chamis, C. C. (NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 6, 2013
Publication Date
March 1, 1992
Subject Category
Structural Mechanics
Report/Patent Number
NAS 1.15:105603
NASA-TM-105603
E-6240
Accession Number
94N10361
Funding Number(s)
PROJECT: RTOP 505-63-53
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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