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6-DOF shaker test input derivation from field test

Conference Proceedings of the Society for Experimental Mechanics Series

Ross, Michael R.; Jacobs-O'Malley, Laura D.; Tipton, David G.; Nelson, Garrett D.; Cross, Kevin R.; Laros, James H.; Harvie, Julie M.

Six degree of freedom (6-DOF) subsystem/component testing is becoming a desirable method, for field test data and the stress environment can be better replicated with this technology. Unfortunately, it is a rare occasion where a field test can be sufficiently instrumented such that the subsystem/component 6-DOF inputs can be directly derived. However, a recent field test of a Sandia National Laboratory system was instrumented sufficiently such that the input could be directly derived for a particular subsystem. This input is compared to methods for deriving 6-DOF test inputs from field data with limited instrumentation. There are four methods in this study used for deriving 6-DOF input with limited instrumentation. In addition to input comparisons, response measurements during the flight are compared to the predicted response of each input derivation method. All these methods with limited instrumentation suffer from the need to inverse the transmissibility function.

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TYPE Conference Poster YEAR 2017
DOIOSTIScopusDOIOSTIScopus

Structural-acoustic mode coupling in a bolted aluminum cylinder

Conference Proceedings of the Society for Experimental Mechanics Series

Pacini, Benjamin R.; Tipton, David G.

This work presents a modal test on a cylindrical bolted structure that initially appeared to be a routine model calibration experiment. However, while reviewing the test data the structure appeared to have two pairs of ovaling modes with identical shapes. Assuming this to be the result of an uninstrumented component of the test article, extensive efforts were conducted to identify this feature. When all options were exhausted, the interaction between the structure and the air contained within was investigated. Contrary to the typical assumption that the fluid-structure interactions are negligible for such a thick walled cylinder, analysis showed that for this test article the acoustic modes of the internal air significantly impacted the structural response. In this case, the acoustic and the structural modes coincided in frequency, causing the first ovaling modes to split into two pairs at different frequencies. Experimental and analytical results are presented that describe this structural-acoustic mode coupling phenomenon.

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TYPE Conference Poster YEAR 2016
DOIOSTIScopus
Results 1–25 of 44
Results 1–25 of 44