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Combine high frequency and low frequency FRF?

Experimenter
Experimenter

I take FRF data on a car body at suspension and engine attachment locations.  We measure a transfer function from the attachment to driver's ear, etc.

 

Currently, we do each measurement twice - once with a larger modal hammer to get low frequency transfer function, and once with a smaller hammer to get the high frequency transfer function.  It is really not possible to use a single hammer to get the entire frequency range of interest.

 

Is it possible to combine the two FRFs taken at each attachment into a single FRF that spans the entire range?

3 REPLIES

Re: Combine high frequency and low frequency FRF?

Siemens Genius Siemens Genius
Siemens Genius

Try the FRF Merge tool.

Start - LMS Test.Lab<version> - Tools - FRF Merge

Re: Combine high frequency and low frequency FRF?

Siemens Legend Siemens Legend
Siemens Legend

The program "FRF Merge" is in the Tools menu.  LMS Test.Lab should already be running, and have a project open with both sets of FRFs.

 

Start_Menu.png

 

Once the interface is open, use the "Folder with LF data" to select the section or run with the low frequency FRF data.  Use "Folder with HF data" to select the high frequency FRF data.  The FRF data should have the same names.

FRF_Merge.png

 

 

The transition band settings allow you to decide what frequency content of the FRFs to keep.  The data can be blended together over the transition zone.

 

 

Re: Combine high frequency and low frequency FRF?

Siemens Phenom Siemens Phenom
Siemens Phenom

One other possible suggestion is using the Merge_Functions command in the Data Calculator. 

 

6-4-2018 9-40-29 AM.jpg