Is there a tutorial on how to set up Signal Express for Impact hammer testing?

[StuMtu]

Is there a tutorial for Impact hammer testing set up? Are there any additional things I need to do to setup the hardware and Signal Express v2.51 software for impact hammer data acquisition?

[dansch]

Hi StuMtu,

You will find a similar forum post to yours here. This forum post discusses some Sound and Vibration Software which can be used to easily complete the type of testing you require. If you navigate to http://www.ni.com/trysv/, you will see an interactive demo of how to use the Sound and Vibration Assistant, which is a tool very similar to Signal Express but with special sound and vibration analysis functions included. This software also includes a pre-made example program for impact testing so that you would have a working application already. By visiting that link, you will also be able to try the software for evaluation. Additionally, I am not sure what kind of hardware you are using to perform your measurements, but I would highly recommend the use of one of our Dynamic Signal Acquisition (DSA) devices which are made specifically for the type of testing you are performing.

[preston_johnson]

there is also an example in the Sound and Vibration assistant for impact test.

[hkm]

Dear Sir

I try  impact testing on S&V Assistant. I also tick export ceherence signal box. But it gave just a straight line with value 1.

While I try from labview example, impact test VI, the coherence is not a straight line. Also, base on literatures on impact test, coherence does'nt produce a straight line. Please advice.

[dsb@NI]

The Sound and Vibration LabVIEW VIs as well as the Frequency Response Step in SignalExpress and Sound and Vibration Assistant returns coherence = 1 when there is only one average. Set the number of averages to anything greater than one, and you will observe that the coherence tends to take shape with each impact added to the average.

[dsb@NI]

And after you have used the basic workspace to identify hit and response locations, I recommend that you switch to the Advanced work area to perform averaged FRF measurements.

Please note, the shown FRF data is saved in the example project viewers. When you run the example, and start triggering impacts, your data and the correct number of averages will be shown in the Data View.

[hkm]

I found that latest S&V Assistant come with imaginary and real component as well. But I can't find any that related to damping ratio? Is it available in S&V assistant?

[dsb@NI]

The Sound and Vibration Assistant does not include a Step to measure the damping ratio and other modal parameters. In LabVIEW, you can implement your preferred algorithm or use existing VIs such as the Modal Parameter Extraction VIs. These can even be built into a custom step that can be used in the Sound and Vibration Assistant.

Not knowing what your specific data may look like, you could also try using cursors in the data view to make damping measurements by either the half power method (FRF) or the log-decrement method (time response).

[nath33160]

Hi Doug,

Could you precise how to use the Modal Parameter Extraction VIs in a custom step in the Sound and Vibration Assistant?

Many thanks!