Impact test , Sound and vibration assistant

[Noby]

I am using Sound and Vibration assistant to get that natural frequencies of a beam using an accelerometer and hammer ( the file is attached ) , although I am using a filter a very wide range of frequencies appears in the output graphs and I think the graphs are giving the wrong answer , so can any one help me to set this test right 

My supervisor told me to use scaling feature with the hammer signal but I do not know why and how .

[_kb]

Noby

I'd like to see if the step configurations are the issue.  Can you try using the Impact Test example?  You can find it in SignalExpress through the Help menu.  Select Open Example » Sound and Vibration Assistant...
and open the project SVA_Impact Test (DAQmx).seproj.  Let us know if you can run this example successfully.  It may even give you the results you are trying to obtain.

As far as the scaling feature, are you referring to A, B, or C weighting?  If so, there is a step specifically for that functionality under Processing » Analog Signals that you can use.

Hope this helps.

[Noby]

I tried the impact test but the graphs at the data view did not change , and My supervisor told me to talk readings till 300 Hz I tried to do this using nyquist theorem but I was getting frequency up to 1K Hz so can I change any thing at the number of samples or sampling frequency , and when I run the program it runs continuously also I am setting it to N samples mode , By weighting do you mean those in the configuration tab of the frequency response step ?!

Thanks in advance

[Noby]

I was trying to get output up  to 100 Hz but the graphs are totally wrong 

[_kb]

When you configure for N Samples, your Analog Input step is going to acquire the number of Samples to Read.  That measurement is going to be the analog signal of all of the vibrations picked up by the accelerometer.  There will be all kinds of different frequencies throughout that set of data.

When you transform the information into frequency data, you want to focus on frequencies below 300 Hz, probably because that is where you'd expect to see the resonant frequency of your test material.  So, even though there is data beyond the range of interest, you're going to be analyzing the amplitudes at those lower frequencies.

Ignore the mention of weighting -- I mistook your application for a different type of project.  I think your supervisor may have been referring to the plot scale.  When you are looking at your graphs, you can set the x-scale to whatever range you'd like.  Double-clicking the max value on the right end of the frequency scale allows us to edit that value.  If you set it to 300, you can limit the display to the data with which you're concerned.  In your log file, you can simply ignore the data logged past the 300 Hz.