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Progress in Operational Analysis of Launch Vehicles in Nonstationary Flight
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Author and Affiliation:
James, George(NASA Johnson Space Center, Houston, TX, United States);
Kaouk, Mo(NASA Johnson Space Center, Houston, TX, United States);
Cao, Timothy(NASA Johnson Space Center, Houston, TX, United States)
Abstract: This paper presents recent results in an ongoing effort to understand and develop techniques to process launch vehicle data, which is extremely challenging for modal parameter identification. The primary source of difficulty is due to the nonstationary nature of the situation. The system is changing, the environment is not steady, and there is an active control system operating. Hence, the primary tool for producing clean operational results (significant data lengths and data averaging) is not available to the user. This work reported herein uses a correlation-based two step operational modal analysis approach to process the relevant data sets for understanding and development of processes. A significant drawback for such processing of short time histories is a series of beating phenomena due to the inability to average out random modal excitations. A recursive correlation process coupled to a new convergence metric (designed to mitigate the beating phenomena) is the object of this study. It has been found in limited studies that this process creates clean modal frequency estimates but numerically alters the damping.
Publication Date: Feb 11, 2013
Document ID:
20130009152
(Acquired Feb 10, 2013)
Subject Category: LAUNCH VEHICLES AND LAUNCH OPERATIONS
Report/Patent Number: JSC-CN-27492
Document Type: Conference Paper
Meeting Information: International Modal Analysis Conference 31st; 11-14 Feb. 2013; Garden Grove, CA; United States
Meeting Sponsor: Society of Experimental Mechanics, Inc.; Bethel, CT, United States
Financial Sponsor: NASA Johnson Space Center; Houston, TX, United States
Organization Source: NASA Johnson Space Center; Houston, TX, United States
Description: 20p; In English; Original contains color illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: ALGORITHMS; CORRELATION; DEGREES OF FREEDOM; DISPLACEMENT; HILBERT TRANSFORMATION; LAUNCH VEHICLES; MATHEMATICAL MODELS; MODAL RESPONSE; PARAMETER IDENTIFICATION; SIGNAL PROCESSING; SPACECRAFT LAUNCHING; TIME DOMAIN ANALYSIS
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