displacement frf

[nareshjaiswal]

I need to plot the five mode shapes of cantilever beam. For that I intend to plot imaginary part of displacement FRF so that by curve fitting the respective peaks  along the length of beam i may plot the mode shape by roving hammer method.

I tried the attached VI. But there are some errors. Can somebody help me to get out of these errors or sugest any alternate VI to find experimental mode shapes please?. Please see the attached files.

What is wrong in this VI?

[natasftw]

The errors tell you what the problem is.  The VI is meant to read a waveform.  You're feeding it an array of waveforms.  Index the array to clear up the first error.

Use the context help (ctrl+h) to understand what the write to measurement file is looking for.

[nareshjaiswal]

Thanks for the Reply.

I am the beginer in in vibration data acquisition and also in Labview.

Could you please correct the VI and sent me back,

Thanking you so much........

[Zwired1]

Right click on the broken wire coming out of the SV Integration.VI and say insert>>array palette>>index array.  That should fix the broken wire, but you'll have to decide if getting only one waveform out of the array of waveforms is what you want.  If there's more than one waveform and you need all of them analyzed and saved to file there's a few more steps to do.  Let us know. 

For the broken wire going to the write to measurement file, the frequency response function is outputing a f0, df,  and a 1D array of phase values.  These could be wired to a build waveform function -- wire them to t0, dt, and Y, repectively -- and the resulting waveform can be wired to the write to measurement file function.  Note that the headers in the measurment file will probably say t0, dt, Y but the information will be f0, df,  and phase.

[nareshjaiswal]

Problem persists.

I could see the graph of Imaginary part of FRF. It consists of some amplitude on y axis and freq on x axis. In that sense it is a two dimensional graph which I could see on screen.

Now I need those  x and y values (numbers) with which that graph is plotted which are  to be saved in two columns of excel file.

I place 'index array', but didnt work

pl see the attachment

[johnsold]

Open the Context Help window. KEEP IT OPEN AT ALL TIMES WHILE PROGRAMMING! Move the wiring tool cursor over the broken wire. The Context Help window will tell you that you have connected a cluster datatype source (Frequency Resonse.vi) to an array datatype sink (Index Array). 

See if you can figure out how to fix it.

Lynn

[nareshjaiswal]

Thanks a lot

I will try..

Regards!