Denna rapport har handlat om utvärderingen av ny utrustning för modelprovning samt
de-sign av ett EXE-program skapat i Labview, som används under en obligatorisk laboration inom
kursen Strukturoptimering och sandwichdesign på Kungliga Tekniska Högskolan, samt inom
forskning på skolan. För att nna en lämplig ersättare skrevs en lista med kravspeci kationer
som användes till att sålla ut möjliga alternativ. Som ersättare valdes en National Instruments
9234 datainsamlingsmodul tillsammans med en National Instruments 9171 chassi, som
imple-menterades tillsammans med en förhållandevis modern dator med operativsystemet Windows 7
Enterprise Edition. Ett mätprogram skapades också i Labview 2011 för laborationen, men kan
modi eras för andra mätningar till forskningen inom skolan, och kan ses i bilaga B.3.
Litteraturförteckning
[1] Wennhage, P., Rosén, A., 2014. Design project in SD2416 Structural Optimisation and
Sandwich Design Autumn 2014 (3hp)
[2] Wallin, H. P., Carlsson, U., Åbom, M., Bodén, H., och Glav, R., 2012. Ljud och Vibrationer
Reviderad version av den tredje upplagan. KTH farkost och yg/ Marcus Wallenberg
La-boratoriet för Ljud- och Vibrationsforskning, Stockholm: Universitetsservice US-AB.
[3] Ewins, D.J. 1991. Modal Testing: Theory and Practice.
Taunton, Somerset, England: Research Sudies Press LTD.
[4] Prevas. inget datum tillgängligt. LabVIEW, gra sk programmering som ger stora
besparing-ar
http://www.prevas.se/labview.html (Hämtad 2015-07-15)
[5] National Instruments. 2014. Understanding Resolution in High-Speed
Digiti-zers/Oscilloscopes.
http://www.ni.com/white-paper/4806/en/ (Hämtad 2015-04-27)
[6] Sandberg, Mats. Sales Engineer vid HBM Sveige.
Kapitel 5
A Allmänt
A.1 Tidsschema
Thesis Work Time schedule
Month Day Work/events Deadline!
April 1
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7 Meeting with Per/ Begin planning
8 Intervjues with teachers
9 Write specifications, requirements
10 and requests
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13 Pilot Study Write report!
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20 Search for hardware Write LabView
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May 1
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4 Order hardware Write report!
5 Write LabView program
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18 Write LabView program
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25 Write LabView program Write report!
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June 1 Write LabView program
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8 Testing Write report!
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15 Testing
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23 Testing Write report!
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August 1
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Johan Berglund
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User manual for measurement of the frequency
response function, FRF, of a sandwich beam.
1. Write the number assigned to the group. This number will be attached to the filenames.
2. Write the number written on the beam. This number will attached to the filenames.
3. Check this box to save the raw-data from the sensors. The data will be saved in a separate file, at the
same location as all other files.
4. Select the folder where the files will be saved by clicking the folder-icon, navigate into the desired
folder, and click the Current Folder button.
5. Write a measurement-time. By increasing the measurement-time, the frequency-increment Δf will
decrease in the FRF. For a good FRF, the time need to be long enough for both signals to settle down
reasonably close to its initial values.
6. Select a sampling rate: The higher the sampling-rate, the higher the maximum frequency of the FRF
will be. But this program automatically cuts off the results at 2000 Hz before plotting and saving.
7. Select the input channel that the impulse hammer is connected to.
8. Select the input channel that the accelerometer is connected to.
9. The Recording indicator will be on during data recording.
10. The # of Measurements indicator displays the number of measurements that has been completed this
session. Quitting the program will reset this to zero. This number will be attached to the filename.
11. Click RECORD to begin recording. No changes can be made while recording.
12. Click TEST to test if the chosen channels are correct, this will open a new window, see page 2.
13. Click QUIT to close the program. Clicking QUIT will not stop a measurement in progress.
14. Click on the tab to select which graph to display: The Signals Graph plots the measured signals from
the two selected channels. The FRF Graph plots the frequency response function.
15. Show, hide or change the plotted lines.
16. Plot tools for zooming.
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Johan Berglund
2015-07-14
1. Displays the Sampling rate during testing, set to maximum of the NI 9234.
2. Use the slider to select the number of samples to be displayed per update on the two graphs below,
point 3 & 4. The smaller the number of samples, the faster the response is displayed, though it will
also be shown for a shorter time. This value is not used in the main measurements.
3. Displays the input signals from the first channel, labeled Hammer Channel (Stimulus) in the main
window. This graph is not recorded or saved.
4. Displays the input signals from the second channel, labeled Accelerometer Channel (Response) in the
main window. This graph is not recorded or saved.
5. Click this button to close down the TestingModeOfInstruments.vi window and return to the main
window, see page 1.
The measurement data are saved as LVM-files, which is a based format, meaning it can be open by
text-editors such as Notepad or Word. But LabView saves all the data using a comma as decimal mark, while Matlab
uses a point as a decimal mark. The m-file “lvm_import.m” on the desktop will import the measurement data,
and change all decimal points from commas to points. Follow the instructions described in the m-files
program-code. In case you forgot to make a copy of the m-file when at the lab, it can be downloaded from mathworks:
http://www.mathworks.com/matlabcentral/fileexchange/19913-lvm-file-import/content/lvm_import.m
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In document
Utvärdering av ny utrustning för modalprovning
(Page 38-50)