Impact testing using labview sound and vibration impact test example

[gileDa]

I am trying to do some impact testing to find natural frequencies. I am completely new to impact testing and labview but am trying to learn as I go. I was hoping to use the 'Impact Test' Example VI that comes with Labview's sound and vibration package to do the testing but I cannot get it to work. I am using the following setup:

• Labview 2021 with sound and vibration tool kit
• c-DAQ 9174
• NI-9232
• B&K impact hammer type 8204
• B&K accelerometer type 4517 

No matter what I try the program will not give a frequency response. The problem seems to be that it does not record the response of the accelerometer. It clearly picks up the signal as it shows up in the live response panel (shown in screenshot) but nothing is shown in the frequency response, Nyquist plot or all data panels. The saved waveform files also only contain the hammer impact data.

I have tried changing the settings for the hammer and accel, changing the values in the node table, changing the window settings and turning it off entirely.

I don't know if this is a simple error in the settings on my part or if the VI is just broken. Any advice would be greatly appreciated.

[Shuggy1 · Accepted solution]

I've had a look through the example and found a bug in the program.

The 'SV get by measurment Type.vi' contains 'SV Get Software Trigger Parameters.vi';This Vi looks through all channels until a channel that is used as a trigger/reference is found and outputs the time domain channels up to that point.

Any Time domain channels listed after the trigger channel are not processed.

This program should work if you put your reference (hammer) channel in the last channel in the list but as a more reliable change see below. It looks like you have your hammer in channel 0 therefore once its removed there are no channels in the data array to process.

I have included an updated 'Impact Test(DAQmx).vi' (saved at ver21sp1) and image of the changes made. All i have done is added a delete from array to extract the trigger reference channel but then pass on all other AI channels.

The documentation for this Project is out of date showing a QMH layout rather than the channel wire approach, this is unhelpful to users trying to understand the project for the first time.

As a beginner to Labview and impact testing i have to say its not the easiest project to follow to could prob make something a lot less complicated your self with 90% of the functionality but that could be maintained.

Good luck hope this helps.

[gileDa]

Thank you so much, that's done the trick!

I've started to build my own as well and you're right I am learning a lot more about lab view than by trying to dissect that monster.

[dsb@NI]

---

@Shuggy1 wrote:

I've had a look through the example and found a bug in the program.

The 'SV get by measurment Type.vi' contains 'SV Get Software Trigger Parameters.vi';This Vi looks through all channels until a channel that is used as a trigger/reference is found and outputs the time domain channels up to that point.

Any Time domain channels listed after the trigger channel are not processed.

This program should work if you put your reference (hammer) channel in the last channel in the list but as a more reliable change see below. It looks like you have your hammer in channel 0 therefore once its removed there are no channels in the data array to process.

I have included an updated 'Impact Test(DAQmx).vi' (saved at ver21sp1) and image of the changes made. All i have done is added a delete from array to extract the trigger reference channel but then pass on all other AI channels.

The documentation for this Project is out of date showing a QMH layout rather than the channel wire approach, this is unhelpful to users trying to understand the project for the first time.

As a beginner to Labview and impact testing i have to say its not the easiest project to follow to could prob make something a lot less complicated your self with 90% of the functionality but that could be maintained.

Good luck hope this helps.

---

Good catch! FYI, this issue was introduced in SVT 2021, captured in BUG 1955615, fixed in PR !300086, and released in the next release of SVT (2023 Q3). The SVT 2023 Q3 released documentation also reflects the latest implementation. Sorry for introducing the bug and sorry for letting the documentation and code get out of sync. Kudos to you for diving in and fixing the issue for you and others for SVT 2021. Can you confirm you found this issue in SVT 2021?