Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation
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University of Cincinnati / OhioLINK
2012
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342729500 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-ucin13427295002021-08-03T06:15:48Z Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation Hassan Pour Dargah, Mahmoud Engineering Force transmissibility Shaker/structure interaction cross-axis sensitivity Stinger This study investigates the interaction of the shakers and structures in structural measurements and the how the transducers and stingers can affect the measurements and estimations. The instrumental variable frequency response function (FRF) algorithm is first used to see if this estimation algorithm is capable of removing the shaker effects from the measurements, which was not successful.The force transmissibility function in different setups was analytically formulated and it is shown that the force drop-out is due to two reasons: The use of voltage-controlled shaker amplifiers and the resonating frequency of the structure itself. Equations that were derived to explain the force transmissibility function show that the major parameters affecting the force level transmitted to the structure is the shaker impedance, frequency of interest and the structure’s response in that frequency. It was observed that for a single degree of freedom system, the drop out occurs exactly at the resonating frequency of structure. For multiple degree of freedom systems, the same governing equations are at play but when excited by more than one shaker, other parameters such as response at each DOF and the level of the force transmitted at each shaker connection are also at play.Experimental results on a circular plate (C-Plate) reinforces the findings in the theory and it is shown that the low cost, prototype, pancake shakers are not able to transfer force to the structure at higher frequencies due to their higher impedance. The stinger effects were also studied and it is shown experimentally that the stinger material and dimension can also affect the force transmissibility. The nylon stingers undergo resonance when tested on a stiff, H shaped test structure (H-Frame) and are not able to transfer enough force at higher frequencies. The metallic stingers on the other hand do not experience any resonances in the same frequency band and they are able to transfer force up to higher frequencies.Finally the effect of the transducers on the measurements was studied on the H-Frame and it is observed that the type of transducer will also introduce some abnormalities in the measurements. It is shown, that the impedance heads are not the best choice for structural measurements, based upon the structures evaluated, and better results can be obtained by using separate force and acceleration transducers. 2012-10-08 English text University of Cincinnati / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342729500 http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342729500 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Engineering Force transmissibility Shaker/structure interaction cross-axis sensitivity Stinger |
| spellingShingle |
Engineering Force transmissibility Shaker/structure interaction cross-axis sensitivity Stinger Hassan Pour Dargah, Mahmoud Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation |
| author |
Hassan Pour Dargah, Mahmoud |
| author_facet |
Hassan Pour Dargah, Mahmoud |
| author_sort |
Hassan Pour Dargah, Mahmoud |
| title |
Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation |
| title_short |
Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation |
| title_full |
Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation |
| title_fullStr |
Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation |
| title_full_unstemmed |
Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation |
| title_sort |
effects of shaker impedance and transducer cross-axis sensitivity in frequency response function estimation |
| publisher |
University of Cincinnati / OhioLINK |
| publishDate |
2012 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342729500 |
| work_keys_str_mv |
AT hassanpourdargahmahmoud effectsofshakerimpedanceandtransducercrossaxissensitivityinfrequencyresponsefunctionestimation |
| _version_ |
1719433667439230976 |