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The use of coherence functions to determine dynamic excitation sources on launch vehicle payloadsThe problem of determining the relative contribution of simultaneous acoustic and mechanical inputs to the response of structures under combined dynamic loads was studied. An analytical technique developed by Bendat for calculating ordinary, partial, and multiple coherence functions, using an iterative nonmatrix approach was applied to data obtained from laboratory tests on a complex structural assembly. Testing was performed in an acoustically 'live' room. Up to three random inputs, having similar spectral content and varying degrees of mutual coherence, and a single output were used. Stationary and nonstationary inputs were used. It was concluded that the technique provided an effective method of identifying sources of dynamic excitation and evaluating their relative contributions to the measured output at structural resonances, for stationary random inputs. An attempt to apply the technique to nonstationary inputs did not yield consistent results.
Document ID
19790017252
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Barrett, S. (Martin Marietta Corp. Denver, CO, United States)
Halvorson, R. M. (Martin Marietta Corp. Denver, CO, United States)
Date Acquired
September 4, 2013
Publication Date
June 1, 1979
Publication Information
Publisher: NASA
Subject Category
Structural Mechanics
Report/Patent Number
MCR-78-556
NASA-CR-3142
Accession Number
79N25423
Funding Number(s)
CONTRACT_GRANT: NAS1-14370
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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