Impact hammer + accelerometer VI needed

[PKP]

Hi everyone,

I'd be really grateful if someone could post a link to a VI that captures the time domain signals from an impact hammer and an accelerometer, and performs an FFT to display and store the frequency response. LabVIEW 2012 or 2013.

Thanks and best regards,

[johnsold]

You may not find a ready-made VI which does all of that.  LabVIEW is a programming language, so you can use the tools provided to create your own programs for yous specific needs.

There are many examples that come with LV. They can help you get started.  Start with DAQ examples. Since you are using an impact hammer, you may want to consider examples which show triggered acquisition. You can trigger on the hammer signal. Mnay of the DAQ examples also include saving to file or displaying results on a graph. Then look at the FFT and Frequency Analysis examples in the Analysis, Signal Processing and Mathematics folder.  

You can open the block diagrams of the examples to see how things were done. If you decide an example is close but not exactly what you want, make a copy under a different name and save it to your project. Then modify the copy as needed. One possibility is that you may want to insert code from an FFT example as a subVI into the DAQ and save example.

If you are new to LabVIEW, look at the on-line tutorials to help you get started.

Lynn

[Henrik_Volkers]

There is a example vi shipped with the Sound and Vibration Toolkit

called: Impact Test 🙂

Description:
This VI performs a triggered acquisiton from two or more channels on the same device.  The first channel should use a sensor mounted on an impact hammer.  The other channel(s) should use accelerometer(s) mounted on the structure under test.

For each impact, the data from each channel is windowed and the frequency response is computed.  The results of the frequency response measurement are displayed as magnitude and phase.  The coherence is also graphed to evaluate the validity of the measured frequency response.

This application example is an advanced example. It uses a robust architecture that uses parallel loops. The top (orange) loop is an event structure that responds to user events by updating front panel objects, enqueueing DAQ states, and setting local variables to control processing. The middle (purple) loop is a state machine that controls the DAQmx analog input task. Continuous data is read from the task, displayed, checked for trigger threshold crossing, and triggered impacts are enqueued.The state machine enables the analog inputs to be started and stopped at the discretion of the user. The bottom (blue) loop is a version of a state machine used to process triggered data, measure averaged frequency response functions, save these FRFs to a UFF 58b file, and update graphs. As triggered data is processed, hits that are not rejected are added to the time-domain state. When there is no more triggered data to process, the cached impact data are used to measure the averaged FRF for each response/stimulus pair and the results are saved to a UFF 58b file. When this processing is complete, the displays for the active node are updated to include the latest data and results.

[PKP]

Dear Henrik,

Thank you very much for your suggestion. It has been a great help.

Best regards,

PKP

[DeepikaB]

Hello,

Thanks for the post!

Could you please attach the impact hammer VI to this post which suits Labview 2015 version?

Thanks,

Deepika

[Bob_Schor]

Go back and read Henrik Volker's Reply, where he tells you where to find the example.  Then get it yourself!

Bob Schor