Attaching a point mass on a beam in Modal

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  • Last Post 08 October 2018
Yazan Thaqakha posted this 28 September 2018

Hello guys,

I am using Ansys workbench 19.0, modal.

I have a beam with a circular cross section, I am attaching a point mass by doing the following steps:
Right click modal-->insert-->Virtual topology
Right click Geometry-->insert--> Point mass

But when I click solve, I get the following warning "One or more Remote Boundary Conditions have been scoped to a solid vertex. Stiff beams have been employed to connect the remote points to the vertex. Check results carefully. You may visualize the created beams on the Solution Information folder".

Why am I getting this warning? What is the correct way to apply a point mass on a beam with a circular cross section at a chosen distance?

Thank you very much for your help.



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SandeepMedikonda posted this 29 September 2018

Hi Yazan,

  I don't quite understand the purpose behind creating a virtual topology?

  I quickly tested what you are saying for a simple beam model in 19.0, I picked one vertex by pressing on the little vertex button (Ctrl+P) and the came back to Geometry, right clicked and inserted a point mass.

As you can see, I don't see any warning messages. So, it is very likely because of the Virtual topology.

Hope this helps.

Regards,
Sandeep
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akhemka posted this 05 October 2018

Hi Yazan,

 

Did you check the FE connectors, visible after the solution to see if the point mass is properly connected to the vertices as indicated in the warning?

 

Regards,

Ashish Khemka

mrife posted this 08 October 2018

Yazan

It helps to keep in mind that the remote point has six degrees-of-freedom (3 translations and 3 rotations) while the one node of the 3D element at the vertex has only 3 degrees-of-freedom (translations).  So the general FEA modeling question is how to connect these together.  Also we would like to connect them so that the model does not have a stress singularity at that one 3D element node.  You can Google the topic and find the myriad of ways it has been addressed over the decades.  WB Mechanical happens to choose to connect the remote point by using several beams connected the the vertex node and other nodes in the vicinity.  After the solution you can visualize this as Ashish discussed.  Then decide for yourself if this modeling method is adequate for your needs.

 

Mike

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