Learning Forum

[Anand V]

I created a 3D frame using line elements (pipe sections). At solution stage, I got 3 error / warning messages. I used the same geometry for Modal analysis and there was no error. May I know where I could be wrong?

[Erik Kostson]

 

Hi

See the error (pivot and UZ ). SOmething is loose in the model. Are you using shared topology or contacts?

Can you show the modes and frequencies from the modal analysis (in there we can see the parts that are loose as they have rigid modes close to 0 Hz).

Thank you

Erik

 

[Anand V]

In modal analysis I find that the frequencies at all modes are zero. I noticed it just now.

I can't make out anything being loose in the model. I have not used shared topology.

How do I check for a loose component if any in the model?

[Erik Kostson]

 

 

 

Hi

So the tube members are not connected to each other (very common issue).

See the mode shapes and they will be members that are loose so rigid body modes with 0 Hz will be visible.

 

On how to model frames see this nice video on how to model and solve frame structure.

https://www.youtube.com/watch?v=3WsFm8NnHNo

 

All the best

Erik

 

 

 

[Anand V]

Thank you, Erik.

I used connect under shared topology and selected all the vertices. It worked !!!