Learning Forum

[kkolha2]

Hi everyone! 

I’m currently working on a simulation in ANSYS Workbench, where I am comparing results from an Undamped Modal Superposition (MSUP) analysis to an Undamped Full Transient Analysis. The deformation results from both analyses match well, While the deformation results from both analyses match closely, I’m encountering a significant difference in the magnitude of acceleration. The Full Transient Analysis yields acceleration values that are much higher in order of magnitude compared to the MSUP results, as shown below,

Has anyone encountered a similar issue or could offer any insights on potential causes for this?

I’ve checked the setup of both analyses and the initial conditions, & Theoretically, the acceleration should also match, but I am still unsure about what might be leading to this difference in magnitude. 

Any help or suggestions would be greatly appreciated!

Thanks!
Kanishka

[Dennis Chen]

 

 

Are you able to share the excel or CSV file of the data in your graph?  Also, I can’t seem to find the APDL equivalent of the directional acceleration in the /solution or /post portion of the command reference in the documentation to see how it’s calculated exactly (beyond the obvious).  the user guide also doesn’t have much detail.  I will look harder but that’s always a good place to start.

Just as a side note, this is why I love the Dyna documentation, it’s just so easy to find stuff.  ^.^

 

 

[kkolha2]

Hello Dennis,
Thank you for taking the time to respond, and apologies for the late reply.

I have attached the CSV Files for both Deformation & Acceleration.
Please find the attached files & Please let me know if you need any further details.

You're right! The documentation does not contain the required information, I will recheck to see if I can find anything.

Thank you so much for your help! :)

Kanishka

[kkolha2]

Sorry,  I was not able to attach them to my post.

https://drive.google.com/drive/folders/1SZe6AtxYEWiC0FpkEz53fXvZTVlfJdBZ?usp=drive_link

Here's a link that directs you to the file.

Thanks!

[Dennis Chen]

 

@kkolha2, I requested access.   I was just going to run a differentiation through the data to see if they would match.    Maybe there’s also an issue with how frequently the data point was taken so differentiating from there created some unexpected outcome.   All just “hypothesis”.   Transient should be 1/20 of the frequency of the highest mode of interest.