Modal parameter extraction from large operating structures using ambient excitation

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A technique called the Natural Excitation Technique or has been developed to response extract response parameters from large operational structure when subjected to random and unmeasured forces such as wind, road noise, aerodynamics, or waves. Six applications of NExT to ambient excitation testing and NExT analysis are surveyed in this paper with a minimum of technical detail. In the first application, NExT was applied to a controlled-yaw Horizontal-Axis Wind Turbine (HAWT). By controlling the yaw degree of freedom an important class of rotating coordinate system effects are reduced. A new shape extraction procedure was applied to this data set with ... continued below

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10 p.

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James, G.H. III; Carne, T.G. & Mayes, R.L. December 31, 1995.

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This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 32 times . More information about this article can be viewed below.

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  • Sandia National Laboratories
    Publisher Info: Sandia National Labs., Albuquerque, NM (United States)
    Place of Publication: Albuquerque, New Mexico

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Description

A technique called the Natural Excitation Technique or has been developed to response extract response parameters from large operational structure when subjected to random and unmeasured forces such as wind, road noise, aerodynamics, or waves. Six applications of NExT to ambient excitation testing and NExT analysis are surveyed in this paper with a minimum of technical detail. In the first application, NExT was applied to a controlled-yaw Horizontal-Axis Wind Turbine (HAWT). By controlling the yaw degree of freedom an important class of rotating coordinate system effects are reduced. A new shape extraction procedure was applied to this data set with good results. The second application was to a free-yaw HAWT. The complexity of the response has prompted further analytical studies and the development of a specialized visualization package. The third application of NExT was to a parked three-bladed Vertical-Axis Wind Turbine (VAWT) in which traditional modal testing could not excite all modes of interest. The shape extraction process used cross-correlation functions directly in a time-domain shape-fitting routine. The fourth application was to ground transportation systems. Ongoing work to improve driver and passenger comfort in tractor-trailer vehicles and to refine automobile body and tire models will use NExT. NExT has been used to process ambient vibration data for Finite Element Model correlation and is being used to study Structural Health Monitoring with ambient excitation. Shape fitting was performed using amplitude and phase information taken directly from the cross-spectra. The final application is to an offshore structure. This work is on-going, however initial studies have found a high-modal density, high noise content, and sparse data set.

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10 p.

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OSTI as DE96003755

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  • 14. international modal analysis conference, Dearborn, MI (United States), 12-15 Feb 1996

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  • Other: DE96003755
  • Report No.: SAND--95-2972C
  • Report No.: CONF-960238--4
  • Grant Number: AC04-94AL85000
  • Office of Scientific & Technical Information Report Number: 168699
  • Archival Resource Key: ark:/67531/metadc625218

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  • December 31, 1995

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  • June 16, 2015, 7:43 a.m.

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  • April 13, 2016, 3:03 p.m.

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James, G.H. III; Carne, T.G. & Mayes, R.L. Modal parameter extraction from large operating structures using ambient excitation, article, December 31, 1995; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc625218/: accessed September 20, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.