Nastran Rigid Body Connection to Concentrated Mass

[Preston_Reed]

Hello, I am trying to make a rigid connection between a concentrated mass and my pump plate.  I am having trouble being able to select the concentrated mass, did i miss a step? 

 

[John_Holtz · Accepted solution]

Hi @Preston_Reed 

You might have missed one of these steps:

1. How did you create the concentrated mass? 
2. Are things hidden in Inventor, such as work point or sketches? If the point where the concentrated mass is applied is hidden, that would explain why the point cannot be selected. (In other words, you need to select a point, such as a work point or sketch point. You do not select the concentrated mass.)
3. Did you try clicking on the "point"? A box selection may not work, and I cannot tell from the video if you clicked or tried box selection only.
4. What version of Inventor Nastran are you using: nnnn.n.n. (If using 2023.0, you need to update to 2023.1.2.)

John

[Preston_Reed]

Hey @John_Holtz , 

1) I created the concentrated mass by right clicking on concentrated mass in the tree, under Model->Idealizations

2) Everything is visible - but I think this may have answered the question, the way I made it was by offsetting from a point that already existed.  Sounds like the appropriate way to do it is by first making a reference point and then applying the mass to the point.  (Sorry new to Nastran)

3) it appears there is no point inside the concentrated mass but it does allow me to select any other point on the part. 

4) Using version 2022.3, cant update to 2023 till next year

[John_Holtz]

Hi @Preston_Reed 

Your item 2 is correct. Creating a concentrated mass does not create a point at the concentrated mass, probably because no one thought to do that. Most of the time, the mass is attached to a point on the model, so creating another point is not necessary.

I wonder what would happen if the center of the rigid connector is attached to the original "offset point". The mass should be connected to the "offset point" even though there is a distance between them, and the rigid connector would be attached to the same "offset point". In theory, everything would be connected together.

John

[Preston_Reed]

Hey @John_Holtz,  I ended up placing a point and using that to place the concentrated mass. Everything has been running well.  Thank you for the help!